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CHAPTER – 17 Forests: Our Lifeline | CLASS 7TH | NCERT SCIENCE IMPORTANT QUESTIONS & MCQS | EDUGROWN

SCIENCE IMPORTANT QUESTIONS & MCQS FOR CLASS 7th

Get Chapter Wise MCQ Questions for Class 7 Science with Answers prepared here according to the latest CBSE syllabus and NCERT curriculum. Students can practice CBSE Class 7 Science MCQs Multiple Choice Questions with Answers to score good marks in the examination. Students can also visit the most accurate and elaborate NCERT Solutions for Class 7Science. Every question of the textbook has been answered here.

Chapter - 17 Forests: Our Lifeline

Question 1.
Which one of the following is not a wild animal?
(a) Bear
(b) Bison
(c) Jackal
(d) Goat

Answer

Answer: (d) Goat

Question 2.
Which one of the following is an animal product?
(a) Gum
(b) Catechu
(c) Honey
(d) Rubber

Answer

Answer: (c) Honey

Question 3.
Roof of the forest made by the branches of the tall trees is called
(a) canopy
(b) crown
(c) understoreys
(d) none of these

Answer

Answer: (a) canopy

Question 4.
Understoreys are formed due to
(a) different types of crowns
(b) different sizes of crown
(c) different heights of trees
(d) all of these

Answer

Answer: (d) all of these

Question 5.
Decomposers convert the dead plant and animal tissues into
(a) clay
(b) humus
(c) inorganic debris
(d) soil

Answer

Answer: (b) humus

Question 6.
Arrange the following components of a food chain in proper sequence – grass, frog, eagle, insects, snake.
(a) Grass → insects → frog → snake → eagle.
(b) Grass → snake → insects → frog → eagle.
(c) Grass → snake → eagle → insects → frog.
(d) All are possible

Answer

Answer: (a) Grass → insects → frog → snake → eagle.

Question 7.
Sequence that represents the series of eating and being eaten is called
(a) food series
(b) food chain
(c) food web
(d) food hub

Answer

Answer: (b) food chain

Question 8.
Which one of the following is a role of forests?
(a) Provide food, shelter, water and medicines
(b) Prevent soil erosion
(c) Prevent flood
(d) All the above

Answer

Answer: (d) All the above

Question 9.
Which among the following forest animals is the smallest?
(a) Fox
(b) Boar
(c) Bison
(d) Porcupine

Answer

Answer: (d) Porcupine

Question 10.
Which of the following is not the name of a tree?
(a) Teak
(b) Sal
(c) Porcupine
(d) Kachnar

Answer

Answer: (c) Porcupine

Match the following:

Column A	Column B
(i) Micro-organisms act upon the dead plant to produce	(a) vulture
(ii) Scavenger	(b) canopy
(iii) Help in maintaining the supply of nutrients to growing plants	(c) food web
(iv) Roof of the forest made by the branches of tall trees	(d) forest protect
(v) Number of food chain	(e) autotrophs
(vi) Soil erosion	(f) purifier of air and water
(vii) Green plants	(g) saprotrophs
(viii) A forest acts as	(h) humus

Answer

Answer:

Column A	Column B
(i) Micro-organisms act upon the dead plant to produce	(h) humus
(ii) Scavenger	(a) vulture
(iii) Help in maintaining the supply of nutrients to growing plants	(g) saprotrophs
(iv) Roof of the forest made by the branches of tall trees	(b) canopy
(v) Number of food chain	(c) food web
(vi) Soil erosion	(d) forest protect
(vii) Green plants	(e) autotrophs
(viii) A forest acts as	(f) purifier of air and water

Fill in the blanks:

1. In a forest, trees form the uppermost layer, followed by ………………. The ………………. form the lowest layer of vegetation.

Answer

Answer: shrubs, herbs

2. Different layers of vegetation provide ………………. and ………………. for animals.

Answer

Answer: food, shelter

3. The forest keeps on ………………. and ………………. and can ……………….

Answer

Answer: growing, changing, regenerate

4. Forests protect the ………………. from erosion.

Answer

Answer: soil

5. ………………. helps forests to grow and regenerate.

Answer

Answer: Soil

6. Branchy part of a tree above the stem is known as the ………………. of the tree.

Answer

Answer: crown

7. Plants release ………………. through the process of photosynthesis.

Answer

Answer: oxygen

8. Microorganisms convert dead animal and plant tissues into a dark-coloured substance called ………………. .

Answer

Answer: humus

Choose the true and false statements from the following:

1. We get various useful products from the forests surrounding us.

Answer

Answer: True

2. Forest is a system comprising various plants, animals and microorganisms.

Answer

Answer: True

3. Forests must be cleared to make the human life safe and comfortable.

Answer

Answer: False

4. Different layers of vegetation provide food and shelter for animals, birds and insects.

Answer

Answer: True

5. Plants release carbon dioxide in the process of photosynthesis.

Answer

Answer: False

6. The various components of the forest are interdependent on one another.

Answer

Answer: True

7. In the forest there is interaction between soil, water, air, and living organisms.

Answer

Answer: True

8. Forests are the lifeline for the forest-dwelling communities.

Answer

Answer: True

9. Forests are the result of hard working of ancient people who have planted most of the forests.

Answer

Answer: False

10. Forests influence climate, water cycle and air quality.

Answer

Answer: True

Question 1.
List some animals which live in deeper areas of the forest.
Answer:
Boars, bisons, jackals, porcupines, elephants, etc., live in the deeper areas of the forest.

Question 2.
Paheli while moving in a forest observed that there was no noise pollution, though lots of heavy vehicles were passing from the nearby highway. Explain why. [NCERT Exemplar; HOTS]
Answer:
Paheli observed that there is no noise pollution in a forest even though there are lots of heavy vehicles passing from the nearby highway. It is because trees present in the forest absorb the noise.

Question 3.
Give the reason behind variations found in the forests of different regions.
Answer:
The variation in the type of plants and animals is found in different forests because of the climatic conditions of that particular area.

Question 4.
Paheli wrote a food chain in the following way:
Frog → Eagle → Insects → Grass → Snake
The chain is not in the correct order. Help her to write the food chain correctly. [NCERT Exemplar]
Answer:
The correct food chain is
Grass → Insects → Frog → Snake → Eagle

Question 5.
Are there similar kind of trees in every forests?
Answer:
No, due to different climatic conditions, there are variations in the types of trees and other plants. From forest to forest.

Question 6.
State the consequence when one food chain is disturbed in an ecosystem.
Answer:
Since, all food chains are interlinked disturbance in one food chain will affect the other food chain in a forest.

Question 7.
What is a canopy?
Answer:
The uppermost branches and leaves of tall trees act like a roof over forest ground, this is called a canopy.

Question 8.
While going inside a forest, it becomes darker. Why?
Answer:
In a forest, big trees, shrubs and other plants are found. They trap solar radiation for photosynthesis.
So, the sunlight does not reach at the forest floor, thus making it dark.

Question 9.
A bunch of seedlings were seen sprouting on a heap of animal dropping in a forest. How do you think is the seedling benefited from the animal dung? [NCERT Exemplar; HOTS]
Answer:
The seedling was being benefited from the animal dung as the decaying animal dung provided nutrients to the growing seedlings.

Question 10.
Consider the following organisms:
Grass, birds, frog, crow, tiger, vulture, toadstool, deer. Which of these
(i) can eat the dead animals
(ii) can form a three step food chain?
Answer:
(i) Crow, vulture
(ii) Grass → Deer → Tiger

Question 11.
Give names of any four birds which you expect to see in a forest. [NCERT Exemplar]
Answer:
The four birds which we expect to see in a forest are jungle crow, hornbill, myna and koel.

Question 12 .
Draw any simple food chain in a pond.
Answer:
A typical food chain in a pond is
Algae → Small fishes → Large fishes

Question 13.
Name any four useful products other than wood, which we get from forests. [NCERT Exemplar]
Answer:
Four useful products other than wood which we get from forests are gum, spices, fodder for animals and medicinal plants.

Question 14.
Deforestation may lead to floods. Why? [NCERT Exemplar]
Answer:
Deforestation leads to floods as lesser number of trees will be available due to deforestation. In the absence of trees, the soil will not hold water leading to floods.

Question 15.
All the needs of animals living in a forest are fulfilled. Justify this statement in a few sentences. [NCERT Exemplar; HOTS]
Answer:
Forest provides homae (shelter), food and water to the animals living there. Thus, all the needs of animals living in a forest are fulfilled.

Forests: Our Lifeline Class 7 Science Extra Questions Short Answer Type Questions

Question 1.
Forests are valuable resources. Explain.
Answer:
Forest products play vital role in socio-economic development. We get food (cereals, pulses, fruits), fire wood, fibre, construction material, industrial products (tannins, lubricants, dyes, resins, perfumes) and products of medicinal importance. It is also the home of diverse wildlife which maintains the ecosystem. Thus, forests are valuable resources.

Question 2.
Plants help in maintaining O₂-CO₂ cycle. Explain it in the light of photosynthesis and respiration.
Answer:
Photosynthesis is the process during which CO₂ is used by the plants and O₂ is released as a products. This O₂ is used by the animals for their respiration and CO₂ is released during it which is again used for photosynthesis by plants. In this way, O₂-CO₂ cycle is balanced by plants.

Question 3.
Forests are called green lungs. Why?
Answer:
The forests provide us oxygen to breathe. If we rapidly cutting down forests means we are cutting down the oxygen supply to us. That is why they are called green lungs.

Question 4.
Two friends shared their experiences of their vacation trip to two different forests. Do you think they would have seen the same type of plants and animals during their respective trips? Give reason. [HOTS]
Answer:
No, they would not have seen the same type of plants and animals. This is so because climatic conditions in the two forests would vary leading to variations in the types of plants and animals.

Question 5.
Write differences between decomposers and scavengers.
Answer:
Difference between decomposers and scavengers is

Decomposer	Scavenger
These are the microbes which break dead organic matter into simple molecules to be used by plants again.	These animals eat the body of dead animals and are called cleaning agent of forests, e.g. jackal, fox, vultures, etc.

Question 6.
What would happen if forests disappear?

Question 7.
Plants are known as the producers of a food chain. Give reason.
Answer:
Plants are known as the producers of a food chain. It is because green plants (autotrophs) make their own food from carbon dioxide and water in the presence of sunlight and chlorophyll by a process called photosynthesis and provide food to all living organisms which live in the forest.

Question 8.
Life would be impossible without plants. Explain, how.
Answer:
All green plants are producers. They make food by the process of photosynthesis using water C02 and sunlight. All forms of animals depend on plants for food. So, if there no plants, no food will be there. Plants are give oxygen also during photosynthesis, and there would be no oxygen in absence of plant. These two basic needs make plants important for us and we cannot think of life without plants.

Question 9.
Y and Z are two types of organism which are found in the forests. Y eats up dead animals while Z breakdown the body of the dead animals into simpler substances.
(a) What is the general name of organism Y?
(b) Write one example of Y type organism.
(c) What is general name of organism Z?
(d) Write one example of Z type organism. (HOTS]
Answer:
(a) Scavenger
(b) Vulture
(c) Decomposers
(d) Fungi (mushroom)

Question 10.
What happens when an animal dies in the forest?
Answer:
The body of the dead animal is eaten up by scavengers like vultures, jackals, hyanas, etc.
These animals do the functions of cleaning in the forest. This also shows that nothing goes waste in the forests.

Question 11 .
Give any four factors which are responsible for the destruction of forests. [NCERT Exemplar)
Answer:
The four factors which are responsible for the destruction of forests are

Construction of roads.
Construction of buildings.
Industrial development.
Increasing demand of wood.

Question 12.
Is it possible to construct a food chain without a producer? State the reason to support your answer.
Answer:
No, in any food chain, producers are always at the beginning. It is the producer which provides food to all living organisms. In a food chain, if producer is absent, then there will be no flow of energy. So, we can say that it is not possible to construct a food chain without a producer.

Question 13.
How can a pipal sapling would have grown on a side wall of some old buildings?
Answer:
Animals disperse the seeds of certain plants with the help of their droppings. Therefore, pipal seed would have come to the wall by a bird dropping . On coming in contact with water and suitable nutrient medium, it would have grown into pipal sapling.

Question 14.
If one component of the forest is removed, what would be its affect on the ecosystem?
Answer:
Every component of forest depend on other. If we remove one, the other will be affected, e.g. if we remove top carnivores (lion/tiger) in a forest, herbivores will increase and if they increase they will end up eating all plants, so ecosystem will get disturbed.

Question 15.
State the role of scavengers in cleaning of our environment.
Answer:
Scavengers eat the dead animals and act as the cleaning agents of our environment. Some of these animals (scavengers) are vultures, crows, jackals, hyena, some insects, etc.

Question 16.
Crown is different from canopy. Explain how.
Answer:
The part of the tree with branches is known as the crown. When the crown of tall trees in the forests forms a roof-like covering over the others plants, it is known as a canopy.

Question 17.
“You conserve forest, you conserve soil”. Do you agree? Justify. [HOTS]
Answer:
Yes, forests bind soil with root and prevent soil erosion. They also maintain fertility of soil and check So, it can be said that conserving forest results in conservation of soil.

Question 18.
Deforestation can increase the earth’s temperature. Is it true? Give reason.
Answer:
Yes, if there are no tress and plants, there will be no photosynthesis. So, no CO₂ of the atmosphere will be used. This will increase the level of CO₂, resulting in the increase of earth’s temperature.

Question 19.
Explain how root system of plants help in the prevention of flood?
Answer:
The root system helps water to seep down in the ground. It helps to maintain the water table throughout the year. Roots of trees normally bind the soil together and stop the erosion of soil.

Question 20.
Sketch a diagram to show how plants maintain the balance between carbon dioxide and oxygen in the atmosphere?
Answer:

Forests: Our Lifeline Class 7 Science Extra Questions Long Answer Type Questions

Question 1.
People say that nothing goes waste in a forest. Can you explain how? [NCERT Exemplar; HOTS]
Answer:
Nothing goes waste in a forest because of the following reasons

Dry leaves and remains of dead animals are converted to a dark coloured substance called humus. This provides nutrients to the plants.
Dead animals become food for vultures, crows, jackals and insects.
Broken branches of trees are used as fuel by the people living in the vicinity of the forest.

Question 2.
“Forest is a dynamic entity, full of life and vitality”. Explain briefly. [HOTS]
Answer:
Forests harbour great variety of plants and animals. Plants provide food to herbivores. Larger number of herbivores means increased availability of food for a variety of carnivores. Wide variety of animals helps forest to regenerate.

Decomposers and scavengers are cleaning agents. So, every entity in the forest plays a key and vital role making it a dynamic living entity, full of life and vitality.

Question 3.
Write the major steps by which we can conserve the forest.
Answer:
Forests maintain balance in nature. There conservation is the need of the hour. We should take the following steps to conserve the forests

(i) Planned harvesting An efficient way to get wood from forests for our requirements is to cut only some of the trees in an area. The uncut trees prevent erosion. Fruits of these trees produce seeds so that new trees can grow. This way the forest cover is maintained.

(ii) Afforestation This is the practice of renewing a forest by planting seedlings or small trees. These days, in our country, planned afforestation is being done not only by the government but also by private organisations for commercial purposes. Selective cutting of trees in these plantations provides wood for construction and also keeps the forest cover intact.

(iii) Protection from fire Huge forest areas are destroyed by fire every year. Fire may occur due to the carelessness of people or due to lightning during a storm or by friction between dry stems and dry branches of trees.
Forest fires are controlled by spraying fire extinguishing solutions from aircrafts or by changing the direction of wind by using strong blowers.

Question 4.
Figure shows a part of a forest.

Write any three activities going on in the forest on the basis of this figure. [NCERT Exemplar]
Answer:
The three activities going on in the forest on the basis of the given figure are

Oxygen is given out by plant leaves.
Carbon dioxide is consumed by the plants to prepare their food by the process of photosynthesis.
Nutrients are being added to the soil by the action of decomposers.

Question 5.
Cycling of papers help in the conservation of the forests. Justify.
Answer:
The papers are made from wood pulp. We derive wood by cutting down trees. If we recycling existing quantity of paper in the market and will not let it decompose, we can stop cutting of forest trees for new raw materials required for paper making.
It takes years to grow a tree and cutting a tree takes only few minutes.
So, we should give a serious thought before cutting a single tree even and should encourage recycling of papers every where in our country and in the world.

Question 6.
Sachin lives in a village, this village is surrounded by a forest. One day he noticed that in nearby pond sedimentation is increased so much that water has become muddy, streams are drying up. There is scarcity of fuel wood. He soon realised that he has to raise the issue of forest protection from cutting down trees, etc. Soon he involved the nearby village people and made an organisation to take an initiative.
Now, answer the following questions
(a) What changes might have Sachin noticed in his area?
(b) Give the porbable reason for such changes mentioned above.
(c) What are the values shown by Sachin? [Value Based Question]
Answer:
(a) Sachin noticed the disturbance in the water cycle in his area like stream drying up. Pond water getting muddy, less availability of fuel wood, etc.
(b) Deforestation.
(c) Love for nature and environmental consciousness.

Question 7.
A snake charmer came to the society and smelled the presence of a cobra near the guardroom. The head of the society agreed to allow the man to search, catch and take away the snake with him. Little Krishi who was seeing all this disagreed. He explained the people that it might disturb the food chain in the environment. Now, answer the following questions
(a) Describe food chain.
(b) Construct a food chain involving snake at one of its level.
(c) What are the values shown by Krishi? [Value Based Question]
Answer:
(a) The sequence of living organisms in which one organism eats another is called a food chain.

(c) Scientific attitude, obligation to maintain the ecosystem of nature.

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CHAPTER – 16 Water: A Precious Resource | CLASS 7TH | NCERT SCIENCE IMPORTANT QUESTIONS & MCQS | EDUGROWN

SCIENCE IMPORTANT QUESTIONS & MCQS FOR CLASS 7th

Chapter -16 Water: A Precious Resource

Question 1.
On which day the world water day is celebrated?
(a) 23rd March
(b) 22nd March
(c) 21st March
(d) None of these

Answer

Answer: (b) 22nd March

Question 2.
Which year was observed as International Year of Fresh Water?
(a) 2003
(b) 2004
(c) 2006
(d) 2002

Answer

Answer: (a) 2003

Question 3.
Which of the following does not show water shortage?
(a) Taps running dry
(b) Long queue for getting water
(c) Marches and protests for demand of water
(d) A family gets three buckets of water per person per day

Answer

Answer: (d) A family gets three buckets of water per person per day

Question 4.
Seas and oceans are full of water on earth. However, a very small percentage of water present on earth is available for us. This percentage is roughly
(a) 0.006%
(b) 0.06%
(c) 0.6%
(d) 6%

Answer

Answer: (a) 0.006%

Question 5.
Which of the following is a way to use water economically?
(a) construction of bawris
(b) Rainwater harvesting
(c) Drip irrigation
(d) Infiltration

Answer

Answer: (c) Drip irrigation

Question 6.
On which of the following day is World Water Day observed
(a) 22 March
(b) 14 November
(c) 2 October
(d) 21 December

Answer

Answer: (a) 22 March

Question 7.
The amount of water recommended by the United Nations for drinking, washing, cooking and maintaining proper hygiene per person per day is a minimum of
(a) 5 litres
(b) 15 litres
(c) 30 litres
(d) 50 litres

Answer

Answer: (d) 50 litres

Question 8.
“Every Drop Counts” is a slogan related to
(a) counting of drops of any liquid
(b) counting of water drops
(c) importance of water
(d) importance of counting

Answer

Answer: (c) importance of water

Question 9.
Water cycle does not involve which of the following?
(a) Evaporation
(b) Condensation
(c) Formation of clouds
(d) Rainwater harvesting

Answer

Answer: (d) Rainwater harvesting

Question 10.
Which of the following inhibits the seepage of rainwater into ground?
(a) A pukka floor
(b) playground
(c) Grass lawn
(d) Forest land

Answer

Answer: (a) A pukka floor

Match the following:

Column A	Column B
(i) Solid	(а) Water under water table
(ii) Liquid	(b) Traditional way of collecting water
(iii) Gas	(c) Water between the hard rocks
(iv) Groundwater	(d) Ice, snow
(v) Aquifer	(e) Water in ponds, rivers, oceans
(vi) Bawri	(f) Water vapour

Answer

Answer:

Column A	Column B
(i) Solid	(d) Ice, snow
(ii) Liquid	(e) Water in ponds, rivers, oceans
(iii) Gas	(f) Water vapour
(iv) Groundwater	(а) Water under water table
(v) Aquifer	(c) Water between the hard rocks
(vi) Bawri	(b) Traditional way of collecting water

Fill in the blanks:

1. Water on the earth has been maintained for millions of years by various processes which make ………………..

Answer

Answer: water cycle

2. the ……………….. form of water is the water vapour.

Answer

Answer: gaseous

3. The ……………….. in the soil indicates the presence of under groundwater.

Answer

Answer: moisture

4. The process of ……………….. of water into the ground is called infiltration.

Answer

Answer: seeping

5. Water in the ……………….. can be easily pumped out with the help of tube wells or handpumps.

Answer

Answer: aquifer

6. ……………….. was the traditional way of collecting water.

Answer

Answer: Bawri

Choose the true and false statements from the following:

1. The water that is fit for use is called fresh water.

Answer

Answer: True

2. The water table varies from place to place and it may even change at a given place.

Answer

Answer: True

3. The water found above the water table is called groundwater.

Answer

Answer: False

4. Drip irrigation has a disadvantage that it is associated with huge loss of water.

Answer

Answer: False

5. Water is essential for all living beings.

Answer

Answer: True

6. Plants wilt and ultimately dry up if they are not watered for a few days.

Answer

Answer: True

Question 1.
Suggest one traditional way of storing water from ancient time.
Answer:
In ancient times, people used to make Bawris to store water.

Question 2.
What is the source of water in each of the following? [NCERT Exemplar]
(a) Wells
(b) Ground
(c) Atmosphere
Answer:
(a) The source of water in wells is groundwater.
(b) The source of water on ground is rain.
(c) The source of water in atmosphere is evaporation.

Question 3.
The earthTooks blue from space. Explain why? [HOTS]
Answer:
The major surface area (71%) of the earth is covered with water. This imparts blue colour to the earth.

Question 4.
Some slogans has been given for the conservation of water. What does the slogan ‘Jal hai to kal hai’ means?
Answer:
This means if you have water, you can think of future, i.e. no life is possible without water.

Question 5.
Reservoir of dam helps us to manage water. How?
Answer:
The reservoir of dam or river can release water at our will. We can divert the flow of water at desired places where it is really needed and we can manage water resource effectively.

Question 6.
The excessive use of water leads to a severe problem. Write the problem.
Answer:
The excessive use of water leads to water scarcity in an area.

Question 7.
How much of the earth’s surface is covered with water?
Answer:
About two-third of the earth’s surface is covered with water.

Question 8.
Mention the year which is celebrated as international year of freshwater?
Answer:
The year 2003 was celebrated as International year of freshwater.

Question 9.
State the consequences, if plants do not get enough water.
Answer:
The plants will wilt and ultimately dry up in lack of water.

Question 10.
Mention the source of groundwater.
Answer:
Rainwater and water from the other sources like rivers, ponds, etc are the source of groundwater.

Question 11.
From where do the workers get water for construction?
Answer:
Workers get water from the underground water.

Question 12.
Can we keep on drawing water from under the ground? How will it affect the water table?
Answer:
No, we cannot keep on drawing water.
It causes the depletion of water table.

Question 13.
State the percentage of actual amount of water available for human use.
Answer:
The actual amount of water available for human use is very little, i.e. approx 0.0006 % of all water found on the earth.

Question 14.
If wells dug to get groundwater, then it dry up after sometime, what initiative should be taken to get water from it again? [HOTS]
Answer:
In the above condition, the groundwater get recharged through the process of infiltration. It replenishes the groundwater.

Question 15.
Water circulates through the water cycle in the three forms. Name them.
Answer:
Water circulates through the water cycle in the three forms, i.e. solid, liquid and gas.

Question 16.
As our population increases, we need more water for drinking, washing and other purposes. Does this affect the water table? Explain.
Answer:
Yes, rising population leads to an increase in consumption and at the same time, a decrease in the seepage of water into the . ground leads to the depletion of water table.

Question 17.
The substance Wis necessary for the normal growth and development of all types of plants and animals. An acute scarcity of substance Whas an ill effect on plants which can hinder the natural process Xin plants causing a severe shortage of /leading to famine. It may also lead the shortage of Zwhich is essential for breathing and respiration. What could W, X, Yand Zbe? [HOTS]
Answer:
W- Water, X- Photosynthesis
Y-Food, Z-Oxygen

Water: A Precious Resource Class 7 Science Extra Questions Short Answer Type Questions

Question 1.
Explain how the traditional use of groundwater is different from the present use.
Answer:
Traditionally in ancient times, people made bawris to collect rainwater in the old buildings. We still use these structures and are reviving them to harness rainwater.

Question 2.
Planting trees help groundwater conservation. Explain how.
Answer:
Plants lose water in the form of water vapour by the process of transpiration. So, forests contribute a lot of water vapours formation which make clouds.
Thus, plants help to revive water cycle.

Question 3.
List the reasons for lowering of water table in cities.
Answer:
Water drawn from underground water gets replenished by seepage of rainwater. The water table does not get affected as long as we draw the same amount of water as is replenished by natural resources like rain.

However, there are number of factors which cause depletion of water table at a very fast rate which is really a matter of concern for everyone of us. Increase in population, industrial and agricultural activities are some common factors affecting water table. Scanty rainfall, deforestation and decrease in the effective area for seepage of water may also deplete the water table.

Question 4.
Complete the given table. (NCERT Exemplar]

	Form of water	Process by which formed	Location where found
(a)	Liquid
(b)	Solid
(c)	Gaseous

Answer:
The complete table is given below:

	Form of water	Process by which formed	Location where found
(a)	Liquid	Condensation and melting	Waterbodies like rivers, lakes, etc.
(b)	Solid	Freezing	Cold regions like high mountains, poles, etc.
(c)	Gaseous	Evaporation	Atmosphere

Question 5.
Place the following statements in a proper order to form a meaningful paragraph.
(a) Which in turn decreases the seepage of rainwater into the ground.
(b) This decreases the open areas like parks and playgrounds.
(c) Increasing population create demand for construction of houses, shops, offices, roads and pavements.
(d) This results in depletion of water table and creates scarcity of more water. INCERT Exemplar]
Answer:
Increasing population create demand for construction of houses, shops, offices, roads and pavements (c). This decreases the open areas like parks and playgrounds (b) which inturn decreases the seepage of rainwater into the ground (a). This results in depletion of water table and creates scarcity of more water (d).

Question 6.
Given below are three states of water in a beaker. These states are inter-convertible. Name the process forward and backforth labelled A, B, C, D, which cause these conversions. [HOTS]

Answer:
A-Melting, 6-Boiling, C- Freezing,
D- Condensation

Question 7.
The water bearing layer of the earth called P is made up of two components O and R, in which R water collect under the ground. The top level of layer Pis called S. When too many tubewells are used in an area, the level of S in that area goes down. What are P, Q, R and S? [HOTS]
Answer:
P- Aquifer, Q- Soil, R- Permeable rocks,
S -Water table

Question 8.
How can you observe the three forms of water (a) in nature and (b) at home? INCERT Exemplar]
Answer:
The three forms of water

in nature are snow (solid), water (liquid) and water vapour (gas).
at home are ice (solid), water (liquid) and steam (gas).

Question 9.
Name some industries familiar to you. Make a list of the products obtained from these and used in our daily life. Discuss how the growing industrial activity is responsible for depletion of water table?
Answer:
Following industries and their products pollute the water:

Leather industries, e.g. shoes and other products.
Chemical factories, e.g. fertilisers, different insect repellant sprays, etc.
Petrochemical industries, e.g. petroleum and different fuels.
Oil industries.

All the above industries release pollutants such as asbestos, lead, mercury, nitrates, sulphur, etc in different rivers, lakes and ponds which are polluting the water and hence is responsible for depletion of water table.

Question 10.
Mention three causes of water scarcity in our country.
Answer:
The three causes of water scarcity in our country are

Rapid urbanisation.
Increased number of industries.
Population explosion.

Question 11.
Certain pattern of the rainfall in our country leads to scarcity of water. Explain that pattern. Which part of the country gets rainfall twice a year?
Answer:
We face shortage of water mainly because water is not evenly distributed by the nature on the earth. Some places such as North East India get so much rains, so that it gets flooded almost every year. On the other hand, Thar desert in Rajasthan may get rains rarely in the monsoon season. This uneven pattern of rains causes water scarcity in India at some places.

Question 12.
A number of problems can be faced due to shortage of water. List some of them.
Answer:
The number of problems that can be faced due to shortage of water are as follows

Less amount of pure drinking water will be available.
Lack of equal distribution of water.
Drought.

Question 13.
From where do the following usually get water? In which form is water present in them?
(a) Clouds
(b) Plants
(c) Mountain tops
(d) Aquifer
(e) Animals (NCERT Exemplar]
Answer:

	Source of water	Form of water
Clouds	Land	Liquid form (droplet of water)
Plants	Soil	Liquid form
Mountain tops	Atmosphere	Solid form
Aquifer	Rain	Underground water
Animals	Waterbodies	Liquid

Question 14.
Some definitions are given which can be corrected by changing one word. Correct them.
(a) Aquifer is groundwater stored between layers of hard rock above the water table.
(b) The process of evaporation of water in the ground is called infiltration.
(c) The evaporation of water from oceans and its arrival back into oceans is called vapour cycle. (NCERT Exemplar]
Answer:
(a) Aquifer is groundwater stored between layers of hard rock below the water table.
(b) The process of seeping of water in the ground is called infiltration.
(c) The evaporation of water from oceans and its arrival back into oceans is called water cycle.

Question 15.
Deforestation can be considered as a reason for depletion of the water table. Comment.
Answer:
Large scale deforestation has occurred to accommodate the growing population, to grow food for them and to provide space for industries. Vegetation slows down the flow of rainwater on land and increases the absorption of water by the soil.
Cutting down of trees and destroying vegetation, therefore interferes with the natural process by which seeping takes place and the groundwater is recharged.
It finally results in the depletion of the water table.

Question 16.
Give the main causes of water scarcity in our country.
Answer:
The main causes of water scarcity in our country are

Rapid urbanisation.
Increased number of industries.
Population explosion.

Water: A Precious Resource Class 7 Science Extra Questions Long Answer Type Questions

Question 1.
Sachin lives in an area where on and off water scarcity is there. He gave a thought to the problem and planned to get a solution. He decided to harvest rainwater in his village. He made efforts to convince the people of his area, built some drainage system and water tanks where rainwater could be collected.
(a) Name few structures he might have built.
(b) Name the process of water cycle, Sachin will use for harvesting water.
(c) Write the methods, Sachin will tell the people to use water wisely. (Value Based Question]
Answer:
(a) Sachin has build up cemented drainage channels in the elevated area and tanks where these channels will collect water.
(b) Sachin is planning to harvest rainwater.
(c) Sachin will educate people to use water judicially in the following way
(i) Use mug for brushing, shaving and bathing.
(ii) Water plants with drip irrigation.
(iii) Use and reuse water in home activities.

Question 2.
Two figures ‘a’ and ‘b’ are given below. Both are revealing two different human activities which are the cause of depletion of water table. Identify the two acts and explain how are these causing the depletion of water resource. [HOTS]

Answer:
(a) Large scale construction
(b) Deforestation
Large scale construction It is main cause of water table lowering because it utilises large amount of water at the time of construction. Most of the time, it is digged water table.

Secondary, when ground surface becomes cemented. It does not allow seepage of rainwater into deeper layers, so rainwater goes waste as run off water and cannot replenish the water table of that particular place.

Deforestation Plants transfer huge amount of water in the form of water vapours. So, when forests are cut down, we interrupt in the process of water cycle of that area. So, no rain occurs at that place and it gradually turns into desert area.

Question 3.
Shishir returned from school and found his mother busy in the kitchen. He noticed that she is making his favourite dosa. Shishir rushed to his mother as he was feeling hungry and found that the tap in the kitchen was leaking. He told his mother to replace it as leaking taps lead to the wastage of water. His mother smiled and ensured him to do the same.
(a) What is water management?
(b) Why should we save water?
(c) What values are shown by Shishir? [Value Based Question]
Answer:
(a) Minimum wastage of water is called water management.
(b) We should save water to prevent water crisis.
(c) Shishir is sincere, responsible and has capability of applying knowledge practically.

Question 4.
What is groundwater? What are the sources of water which are fed by groundwater?
Answer:
The wells, tubewells and handpumps are main sources of water for many people. The water in these sources is the groundwater. It is upper level of underground water which occupies all the spaces in the soil and rocks and form a water table as shown in the figure below:

The upper limit of groundwater is called water table. It represents the depth of water filled area at a given place. The water table rises and falls depending upon the amount of rainwater that seeps into the groundwater and how much groundwater is drawn out for irrigation and industry. The seeping down of rainwater into the groundwater is called infiltration. The groundwater, thus gets recharged by this process.

At some places, the groundwater is stored between layers of hard rock below the water table. This is aquifer which contains the groundwater usable by tubewells and handpumps. These sources however, have limited sources of water and may get exhausted if used excessively.

Question 5.
Water is very precious for all the living beings.
What will happen in future, if we do not save water now? [NCERT Exemplar]
Answer:
Water is needed for various life activities. If we continue the misuse of water and do not conserve it, the groundwater level will be depleted. This may result into various consequences like

Lowering of the water table Excessive pumping can lower the groundwater table.
Reduced surface water supply Groundwater and surface water are connected. When groundwater is overused, the lakes, streams and rivers connected to groundwater, can also have little supply.
Loss of plants from land We fully depend on the plants for food directly or indirectly. Plants need water to prepare their food. If there will be scarcity of water on earth, the plants will be unable to prepare their food. This inturn will lead to the end of the life because world without plants means no food, no oxygen, not enough rain and other innumerable problems.
Therefore, it is true that water is a precious resource.

Question 6.
All the rain that falls over an area is not utilised. Do you agree? Explain.
Answer:
Precipitation (rain) is a natural process and is a part of natural water cycle. It replenishes all the natural resources of water like ponds, lakes, river and finally oceans and seas too.
When we say utilisation of rainwater, we mean that rain in a particular area.
Yes, it is not properly utilised as most of the water is run off as surface water to the rivers and goes to oceans.
We can harness/harvest this water to local waterbodies like ponds, lakes and groundwater by proper planning as it is being done in some districts of Rajasthan successfully.

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CHAPTER – 15 Light | CLASS 7TH | NCERT SCIENCE IMPORTANT QUESTIONS & MCQS | EDUGROWN

SCIENCE IMPORTANT QUESTIONS & MCQS FOR CLASS 7th

Chapter - 15 Light

Question 1.
The path of the light is
(a) always a straight line
(b) a curved line
(c) a zig-zag line
(d) depends on the medium

Answer

Answer: (a) always a straight line

Question 2.
Which one shows lateral inversion?
(a) Plane mirror
(b) Convex mirror
(c) Concave mirror
(d) All of these

Answer

Answer: (a) Plane mirror

Question 3.
Image formed by a plane mirror is
(a) virtual and erect
(b) real and erect
(c) virtual and inverted
(d) real and inverted

Answer

Answer: (a) virtual and erect

Question 4.
Boojho and Paheli were given one mirror each by their teacher. Boojho found his image to be erect and of the same size whereas Paheli found her image erect and smaller in size. This means that the mirrors of Boojho and Paheli are, respectively
(a) plane mirror and concave mirror
(b) concave mirror and convex mirror
(c) plane mirror and convex mirror
(d) convex mirror and plane mirror

Answer

Answer: (c) plane mirror and convex mirror

Question 5.
Which of the following can be used to form a real image?
(a) Concave mirror only
(b) Plane mirror only
(c) Convex mirror only
(d) Both concave and convex mirrors

Answer

Answer: (a) Concave mirror only

Question 6.
If an object is placed at a distance of 0.5 m in front of a plane mirror, the distance between the object and the image formed by the mirror will be
(a) 2 m
(b) 1 m
(c) 0.5 m
(d) 0.25 m

Answer

Answer: (b) 1 m

Question 7.
You are provided with a concave mirror, a convex mirror, a concave lens and a convex lens. To obtain an enlarged image of an object you can use either
(a) concave mirror or convex mirror
(b) concave mirror or convex lens
(c) concave mirror or concave lens
(d) concave lens or convex lens

Answer

Answer: (b) concave mirror or convex lens

Question 8.
An erect and enlarged image can be formed by
(a) only a convex mirror
(b) only a concave mirror
(c) only a plane mirror
(d) both convex and concave mirror

Answer

Answer: (b) only a concave mirror

Question 9.
You are provided with a convex mirror, a concave mirror, a convex lens and a concave lens. You can get an inverted image from
(a) both concave lens and convex lens
(b) both concave mirror and convex mirror
(c) both convex mirror and convex lens
(d) both convex mirror and concave lens

Answer

Answer: (c) both convex mirror and convex lens

Question 10.
An image formed by a lens is erect. Such an image could be formed by a
(a) convex lens provided the image is smaller than object.

(b) concave lens provided the image is smaller than object.

Answer

Answer: (b) concave lens provided the image is smaller than object.

Match the following:

Column A	Column B
(i) Concave lens	(a) Lateral inversion
(ii) Always virtual image	(b) Reflecting surface is bulged out
(iii) Changing position of image	(c) Concave mirror
(iv) Wax paper	(d) Seven colours
(v) Image obtained on screen	(e) Real image
(vi) Convex mirror	(f) Translucent
(vii) Used by dentists	(g) Thinner in the middle
(viii) White light composed	(h) Concave lens

Answer

Answer:

Column A	Column B
(i) Concave lens	(g) Thinner in the middle
(ii) Always virtual image	(h) Concave lens
(iii) Changing position of image	(a) Lateral inversion
(iv) Wax paper	(f) Translucent
(v) Image obtained on screen	(e) Real image
(vi) Convex mirror	(b) Reflecting surface is bulged out
(vii) Used by dentists	(c) Concave mirror
(viii) White light composed	(d) Seven colours

Fill in the blanks:

1. Uneven surfaces show ………………….. reflection.

Answer

Answer: irregular

2. Incident ray, the reflected ray ………………….. and lie in the same …………………..

Answer

Answer: normal,plane

3. Laws of ………………….. is applicable in playing back shots in the carroms.

Answer

Answer: reflection

4. Changing of right side to left is called …………………..

Answer

Answer: lateral inversion

5. The inner surface of a steel spoon acts as a ………………….. mirror.

Answer

Answer: concave

6. The outer surface of a flat steel plate acts as a ………………….. mirror.

Answer

Answer: plane

7. The outer shining surface of a round bottom steel bowl acts as a ………………….. mirror.

Answer

Answer: convex

8. The inner surface of the reflector of a torch acts as a ………………….. mirror.

Answer

Answer: concave

Choose the true and false statements from the following:

1. Concave mirror is converging in nature.

Answer

Answer: True

2. Convex mirror is diverging in nature.

Answer

Answer: True

3. Plane mirror forms virtual image.

Answer

Answer: True

4. Concave mirror has a virtual focus.

Answer

Answer: False

5. Spherical mirrors do not obey laws of reflection.

Answer

Answer: False

6. During lateral inversion, the image becomes inverted.

Answer

Answer: False

7. Angle between incident ray and reflected ray is double that of the angle of incidence.

Answer

Answer: True

Question 1.
Briefly mention whether mirror change the direction of light.
Answer:
Yes, when a ray of light is incident on the mirror surface, then the mirror changes the direction of light.

Question 2.
The image formed by a lens is always virtual, erect and smaller in size for an object kept at different positions in front of it. Identify the nature of the lens. (NCERT Exemplar]
Answer:
Such types of lenses which always form virtual, erect and smaller image in spite of the different positions of an object are called concave lens.

Question 3.
Observe the given figures carefully.

The given figures show the path of light through lenses of two different types represented by rectangular boxes A and B. What is the nature of lenses A and B ? [NCERT Examplar]
Answer:
Since, in first case light rays are converging towards a point, so the lens A will be convex and in case of lens 8, light rays diverge or spread out. So, the lens will be concave lens.

Question 4.
Name the colours include in the composition of sunlight.
Answer:
As we know that sunlight consists of mixture of seven colours (i.e. VIBGYOR).

Question 5.
In the formation of a rainbow, what acts as tiny prisms?
Answer:
In the formation of a rainbow, the raindrops suspended in the atmosphere acts as tiny prism.

Question 6.
Briefly mention what makes things visible to us.
Answer:
When a light ray falls on an object, then reflected light ray which comes from the object when A falls on our eys, allows us to see things around us.

Question 7.
Name the type of lens which diverges a beam of parallel rays of light.
Answer:
The lens which diverges a beam of parallel rays of light is a concave lens.

Question 8.
Is the image formed by a plane mirror is always upright?
Answer:
Yes, the image formed by the plane mirror is always upright.

Question 9.
Explain why are concave and convex mirrors called spherical mirrors.
Answer:
Concave and convex mirrors are the parts of sphere whose one side is polished or silvered. So, they are called spherical mirrors.

Question 10.
Is it possible to obtain the image on the screen when the candle is too closed to the concave mirror?
Answer:
No, when the candle is too closed to the concave mirror.

Question 11.
Can you get a real image at any distance of the object from the convex mirror?
Answer:
No, we cannot get a real image for any position of an object from the mirror because convex mirror always forms virtual, erect and diminished image in spite of the position of object.

Question 12.
Can you name the mirrors used as side mirrors in scooters?
Answer:
Yes, in the side mirror of scooters, convex mirror is used to have a wider field of view of the traffic.

Question 13.
Explain why concave mirror is known as a converging mirror.
Answer:
Concave mirror is known as a converging mirror because it converges a beam of parallel rays of light (reflecting from it) at one point.

Question 14.
Name the phenomenon that is involved in the formation of image of an object by a concave mirror.
Answer:
Reflection of light is the name of a phenomenon which is involved in the formation of image of an object by a concave mirror.

Question 15.
Mention the type of image formed on a cinema screen.
Answer:
Real image is an image which is formed on a cinema screen.

Question 16.
As we know that an image is formed by the actual intersection of rays and can be obtained on the screen. So, state whether it is real or virtual image.
Answer:
Since, after the actual intersection of rays, the image obtained on the screen is always real image.

Question 17.
State in brief about the term lens.
Answer:
A transparent material which is bounded by both or one spherical surface is known as a lens.

Question 18.
Name the phenomenon that is involved in the formation of image of an object by a convex lens.
Answer:
Refraction of light is the name of a phenomenon which is involved in the formation of image of an object by a convex lens.

Question 19.
Give the form of energy that produces the sensation of vision.
Answer:
Light energy is the form of energy which produces the sensation of vision.

Question 20.
What type of mirror is used as a side mirror in a scooter? Why is this type of mirror chosen? [NCERT Exemplar]
Answer:
Convex mirror is used as a side mirror in a scooter because it can form images of objects spread over a larger area.
So, this helps the driver to view the traffic over a large area behind them.

Question 21.
Briefly mention how many types of lens are there. Explain each of them.
Answer:
There are two types of lenses.
The lens which is thinner in the middle than at the edges is called a concave lens while the lens
which is thicker in the middle than at the edges is called a convex lens.

Question 22.
Consider if one half of a convex lens is covered with a black paper, then state whether this lens produces a complete image of the object.
Answer:
If one half of a convex lens is covered with a black paper, then yes, the convex lens will produce the complete image of the object.

Question 23.
Briefly tell that how many reflected rays can be obtained from a single incident ray in respect of a plane mirror.
Answer:
For a single incident ray, there will be only one reflected ray that can be obtained in respect of a plane mirror.

Question 24.
State in brief what we can demonstrate by rotating Newton’s colour disc very fastly.
Answer:
By rotating Newton’s colour disc, we can demonstrate that when seven colours are mixed together, then a white colour is formed.

Question 25.
Mention the name of lens whioh can converge the sun’s rays to a point and burn a hole in the piece of paper. (HOTS]
Answer:
Convex lens is a lens which can converge the sun’s rays to a point and burn a hole in the piece of paper.

Question 26.
An erect and enlarged image of an object is formed on a screen. Explain how this could be possible.
Answer:
An erect and enlarged image of an object is formed only by the concave mirror or convex lens when object is inverted and placed between F and 2F.

Light Class 7 Science Extra Questions Short Answer Type Questions

Question 1.
The distance between an object and a convex lens is changing. It is noticed that the size of the image formed on a screen is decreasing. Is the object moving in a direction towards the lens or away from it? (NCERT Examplar; HOTS]
Answer:
In case of convex lens, when we move the object far away from the lens, the size of image decreases and ultimately, when object is at infinity, it will form a point image at focus.

Question 2.
Two different types of lenses are placed on a sheet of newspaper. How will you identify them without touching? [HOTS]
Answer:
On identifying the letters of newspaper, we can differentiate the two types of lenses.
If image is large or magnified, then the lens is a convex lens and if the image is smaller or diminished in size for all the positions of object, then the lens is concave .

Question 3.
Briefly state the characteristics of image formed by a plane mirror.
Answer:
Characteristics of the Images Formed by a Plane Mirror
Now, we will describe the various characteristics of the images formed in a plane mirror by taking the example of the image of the candle.

When we see the mirror, the image of candle appears to be formed behind the mirror.
Now, pW a vertical screen behind the plane mirror (where the image of candle appears to be situated), then we will notice that the image of candle cannot be formed on the screen. Even if the screen is placed in front of the plane mirror, then the image of candle cannot be formed on the screen. Since, the image of candle formed in the plane mirror cannot be formed on a screen, which means that the image of candle in the plane mirror is a virtual image.
If we see the figure, then we will find that the length and breadth of the image of the candle and its flame to be the same as that of the original candle and its flame. The image of candle in the plane mirror is of the same size as the original candle.
Also if we see the figure, then we will find that the candle has a flame at the top and the image of candle also has a flame at the top. So, the top of candle remains at the top in the image. In the same way, the bottom of candle remains at the bottom in an image. Such an image is called an erect image (or upright image). Therefore, the image formed by a plane mirror is erect.

Question 4.
The side mirror of a scooter got broken. The mechanic replaced it with a plane mirror. Mention any inconvenience that the driver of the scooter will face while using it. [NCERT Examplar; HOTS]
Answer:
As we know that the side mirror of a scooter must be of convex mirror so that we can view a wide range of traffic spread over a large area. But if plane mirror is used, we are not able to see large area of traffic which may be difficult for driving vehicle and can cause accident.

Question 5.
We need a shiny surface for reflection. Explain why.
Answer:
Since, the extent of reflection depends upon the shine and smoothness of the surface. So, greater the shining and smoothness of the surface, greater will be the reflection. So, this is a reason why we require a shiny surface for reflection.

Question 6.
Differentiate between a plane mirror, concave mirror and a convex mirror without touching them.
Answer:
These mirrors can be differentiated by bringing our face close to each mirror turn by turn. Since, a plane mirror will produce an image of the same size as our face while a concave mirror will produce a magnified image and our face will look much bigger and on other sides, a convex mirror will produce a diminished image and our face will look much smaller like a small child.

Question 7.
The concave reflecting surface of a torch got rusted. What effect would this have on the beam of light from the torch? [NCERT Exemplar]
Answer:
If the reflecting surface of a torch got rusted, it produces diffused light with lower intensity and the objects are not clearly visible in this diffused and lower intensity of light.

Question 8.
Mention the type of image
(a) which can be formed on the screen.
(b) which cannot be formed on the screen.
Answer:
(a) The image which can be formed on the screen is real image.
(b) The image which cannot be formed on the screen is virtual image.

Question 9.
Mention any two letters of English alphabet whose image formed in a plane mirror appears exactly similar to the letters.
Answer:
Since, image formed by the plane mirror shows lateral inversion, i.e. left seems to right or vice-versa. But in the case of alphabets A and H, these letters show the same image in the plane mirror.

Question 10.
A shopkeeper wanted to fix a mirror which will give a maximum view of his shop. What type of mirror should he use? Give reason.
[NCERT Exemplar; HOTS]
Answer:
If a shopkeeper wanted to fix a mirror which will give him maximum view of his shop, he should use convex mirror.
In case of convex mirror, it will give a wider field of view, i.e. it can collect light from a large area spread over them.

Question 11.
State the correct sequence (1-7) of colours in the spectrum formed by the prisms A and B shown in the figure.

Answer:
When a white light is passed through a prism, it disperses into its seven constituent colours.

Question 12.
Suppose we wish to obtain the real image of a distant tree. Explain two possible ways in which we can do it. [NCERT Exemplar]
Answer:

In first case, we will use a concave mirror, as we know that concave mirror can form real image, i.e. image on screen. The image of distant tree will be at focus in case of concave mirror.
In second case, we can use a convex lens as it forms real image of a distant object at focus, i. e. image of distant tree in case of convex lens will be formed at focus.

Question 13.
Explain the term lateral inversion.
Answer:
When an image is formed by the mirror in such a way that the left side of image is object’s right side and right side of image is object’s left side. So, this process of change in the sides of the object as well as of image is known as lateral inversion.

Question 14.
State the characteristics of images formed by a concave mirror.
Answer:
The characteristics of image formed by a concave mirror are:

The image formed by a concave mirror is not always the same size as the object. It can be either larger or smaller depending on the distance of the object to the mirror.
The image formed by a concave mirror is inverted when the object is kept far from the mirror. So, when it is brought very close to the concave mirror, then an erect and enlarged image is formed.

Question 15.
Boojho made light from a laser torch to fall on a prism. Will he be able to observe a band of seven colours? Explain with a reason. [NCERT Exemplar; HOTS]
Answer:
No, he will not observe band of seven colours because laser light consists of monochromatic light of single colour.
But seven colours of bands are only observed, when a white light is passed through a prism and dispersion takes place.

Question 16.
Briefly explain why in ambulance words are written laterally inverted. [HOTS]
Answer:
In case of mirror, the image formed by it is laterally inverted, i.e. left seems to be right and right seems to be left. So, in ambulance there is emergency for patients to reach hospital and by viewing in rear mirror, it can be easily identified of a vehicle and everyone give him a way.

Question 17.
Assume, a person is standing in front of a plane mirror. The distance between the mirror and his image is 6 m. If the person moves 2 m towards the plane mirror, what would be the distance between the person and his image? [HOTS]
Answer:
Since, the image is 6m away from the plane mirror. So, it means that the object is also 6m away from the mirror.

[Because OP = PI]
So, when the person moves 2 m towards the plane mirror, then the distance between the person and the plane mirror will be equal to (6 m – 2 m) = 4 m, this means that distance between the image and the mirror will be 4m.

The distance between the person and his image = PO’+ PI’= 4 + 4 = 8m

Light Class 7 Science Extra Questions Long Answer Type Questions

Question 1.
Explain with the help of an activity that when seven colours are mixed together, then white colour is formed.
Answer:
Firstly, take a circular cardboard disc of about 10 cm diameter, then divide this disc into seven equal segments and paint the seven colours of white light (red, orange, yellow, green, blue, indigo and violet) on these segments (as shown in figure given ). Instead of painting the segments, we can also paste seven coloured papers on these segments. So, this disc painted with the seven colours of spectrum is called Newton’s disc. Now, make a small hole at the centre of the disc.

Fix the disc loosely on the tip of a refill of a ball pen. Be confirm that the disc can rotate freely. Now, rotate the disc quickly in day light. So, when the disc is rotated very fast, then all the seven colours mix together due to which the disc appears to be white (see figure). Therefore, the rapid rotation of Newton’s colour disc tells us that mixing of seven colours of the spectrum can give us white light.

Question 2.
It was observed that when the distance between an object and a lens decreases, the size of the image increases. What is the nature of this lens? If you keep on decreasing the distance between the object and the lens, will you still able to obtain the image on the screen? Explain. [NCERT Exemplar; HOTS]
Answer:
On decreasing the distance between the object and lens, the size of the image increases, the nature of the lens will be convex type.
If the distance between object and lens is less than the focus of the lens, then it forms a virtual image and this image cannot be obtained on a screen but formed on the same side of the object.

Question 3.
Give the definition dispersion of light. Also, explain why does it take place? Draw a diagram to show the dispersion of white light by a glass prism.
Answer:
In the year 1665, Newton discovered by his experiments with glass prisms that white light (like sunlight) consists of a mixture of lights of seven colours. Newton found that if a beam of white light is passed through a glass prism, then the white light splits to form a band of seven colours on a white screen . The band of seven colours formed on a white screen, when a beam of white light is passed through a glass prism, is known as spectrum of white light. The seven colours of the spectrum are Red, Orange, Yellow, Green, Blue, Indigo and Violet .

So, dispersion of light is phenomenon of splitting up of white light into seven colours on passing through a transparent medium like a glass prism. The formation of spectrum of seven colours indicates that white light is a mixture of seven colours. White light can be sunlight. So, now we can say that the sunlight consists of seven colours.
We can mix these colours to get white light. This can be done by using Newton’s disc, let us try this.

Question 4.
You are given three mirrors of different types.
How will you identify each one of them? [NCERT Exemplar]
Answer:
We can identify the mirrors by forming image of an object.

Plane mirror In case of plane mirror, image will be virtual, erect and of same size as that of object.
Concave mirror In case of concave mirror, image may be real, virtual and magnified or diminished.
Convex mirror In case of convex mirror, image formed will always be virtual, erect and diminished.

Question 5.
Namit was driving a car and suddenly became aware of a loud sound coming from behind. He looked through his rear view mirror and saw an ambulance. He recalled reading that such emergency vehicles often have their name written in the mirror (AMBULANCE) or writing, i. e.
He quickly made way for the ambulance, murmuring a quick prayer for the speedy recovery of the patient inside the ambulance.
(a) Name the type of mirror which is used as a rear view mirror and why?
(b) Mention values did Namit exhibit. (Value Based Question]
Answer:
(a) Convex mirror is a mirror which is used as a rearview mirror. It is used to get a wide view of traffic behind.
(b) The values exhibit by Namit here is courtesy concerned for other, sympathy, knowledgeable.

Question 6.
One day, Ramesh’s friend was performing their respective experiments given by their teacher. While sitting in the practical lab instead of performing experiment, Ramesh was playing with his meter scale. All the sudden, he held the scale in his hand and started moving in front of tubelight, then he observed the seven colours of white light. After sometimes, he got scolded by his lab teacher for not performing the experiment.
(a) Give the name of phenomenon that leads to the formation of band of seven colours.
(b) Name the constituent colours of white light.
(c) Mention the values shown by Ramesh here. (Value Based Question]
Answer:
(a) Dispersion of white light is the name of phenomenon which leads to the formation of band of seven colours.
(b) There are seven constituent colours of white light, they are Violet, Indigo, Blue, Green, Yellow, Orange, Red (i.e. VIBGYOR).
(c) Ramesh seems to be quite innovative with respect to the scientific methods and also very eager to learn science regarding phenomena.

Question 7.
Last Sunday Girish’s mother, Priyanka was preparing the dinner in her kitchen for Girish and his father. Both of them were feeling so much hungry and they sat ideally on their respective chairs and having empty plates and spoons on their dinning table. They were shouting like a 5 years old child that they wanted the dinner so much eagerly in order to fulfil their stomach. At the sometime, Girish’s mother served the cooked food to both of them and the moment, when Girish was just about to eat the rice with the help of spoon, he noticed that the spoon has such a shining surface that it reflected the light rays incident on it.
(a) Explain the importance of shining surface in the reflection of light.
(b) Name the type of spherical mirror represented by the shining steel spoon.
(c) Mention the values shown by Priyanka here towards her family. [Value Based Question]
Answer:
(a) As we know that the extent of reflection depends upon the shining of surface. So, greater the shining of the surface, more will be the reflection.
(b) Both convex and concave mirrors are represented by the shining steel spoon.
(c) The values shown by Priyanka here is concern and a satisfaction that she gets after serving the cooked food to her son and her husband.

Rohit0 comments

CHAPTER – 14 Electric Current and Its Effects | CLASS 7TH | NCERT SCIENCE IMPORTANT QUESTIONS & MCQS | EDUGROWN

SCIENCE IMPORTANT QUESTIONS & MCQS FOR CLASS 7th

Chapter - 14 Electric Current and Its Effects

Question 1.
In making a battery
(a) positive terminal of one cell is connected to the negative terminal of the next cell
(b) positive terminal of one cell is connected to the positive terminal of the next cell
(c) negative terminal of one cell is connected to the negative terminal of the next cell
(d) none of the above

Answer

Answer: (a) positive terminal of one cell is connected to the negative terminal of the next cell

Question 2.
Where can the key or switch be placed in the circuit?
(a) Left side of the battery
(b) Right side of the battery
(c) Can be placed anywhere in the circuit
(d) Near the positive terminal of the bulb

Answer

Answer: (c) Can be placed anywhere in the circuit

Question 3.
Which one of the following is based on the heating effect of current?
(a) Geyser
(b) Hair dryer
(c) Immersion rod
(d) All of these

Answer

Answer: (d) All of these

Question 4.
The coil of wire contained in an electric heater is known as
(a) component
(b) element
(c) circuit
(d) spring

Answer

Answer: (b) element

Question 5.
The amount of heat produced in a wire depends on
(a) material
(b) length
(c) thickness
(d) all of these

Answer

Answer: (d) all of these

Question 6.
Which mark is necessary on electric appliances?
(a) AGMARK
(b) ISI
(c) FICCI
(d) KSK

Answer

Answer: (b) ISI

Question 7.
When an electric current flows through a copper wire AB as shown in Figure, the wire

(a) deflects a magnetic needle placed near it
(b) becomes red hot
(c) gives electric shock
(d) behaves like a fuse

Answer

Answer: (a) deflects a magnetic needle placed near it

Question 8.
Choose the statement which is not correct in the case of an electric fuse.
(a) Fuses are inserted in electric circuits of all buildings.

(b) There is a maximum limit on the current which can safely flow through the electric circuits.

(c) There is a minimum limit on the current which can safely flow in the electric circuits.
(d) If a proper fuse is inserted in a circuit it will blow off if current exceeds the safe limit.

Answer

Answer: (c) There is a minimum limit on the current which can safely flow in the electric circuits.

Question 9.
When a switch is in OFF position.
(i) circuit starting from the positive terminal of the cell stops at the switch.
(ii) circuit is open.
(iii) no current flows through it.
(iv) current flows after some time.
Choose the combination of correct answer from the following:
(a) all are correct
(b) (ii) and (iii) are correct
(c) only (iv) is correct
(d) only (i) and (ii) are correct

Answer

Answer: (b) (ii) and (iii) are correct

Question 10.
Which of the following precautions need not be taken while using electric gadgets / appliances/circuit?
(a) We should never touch a lighted electric bulb connected to the mains.

(b) We should never experiment with the electric supply from the mains or a generator or an inverter.
(c) We should never use just any wire or strip of metal in place of a fuse.
(d) We should never turn the switch in ON position.

Answer

Answer: (d) We should never turn the switch in ON position.

Match the following:

Column A	Column B
(i) Switch	(a) Coil of wire which heats up when electricity current is supplied
(ii) Battery	(b) Blows off, if the current exceeds safe limit
(iii) Element	(c) Consumes less energy than a bulb
(iv) Filament	(d) Mark that ensures that the electric appliance is safe to handle
(v) Fuse	(e) Supplies current to the circuit
(vi) MCBs	(f) Turns the circuit ON and OFF
(vii) CFL	(g) Turn OFF if current exceeds safe limit
(viii) ISI	(h) Wire in the bulb which glows

Answer

Answer:

Column A	Column B
(i) Switch	(f) Turns the circuit ON and OFF
(ii) Battery	(e) Supplies current to the circuit
(iii) Element	(a) Coil of wire which heats up when electricity current is supplied
(iv) Filament	(h) Wire in the bulb which glows
(v) Fuse	(b) Blows off, if the current exceeds safe limit
(vi) MCBs	(g) Turn OFF if current exceeds safe limit
(vii) CFL	(c) Consumes less energy than a bulb
(viii) ISI	(d) Mark that ensures that the electric appliance is safe to handle

Fill in the blanks:

1. Our body is a ………………….. of electricity.

Answer

Answer: conductor

2. An electric cell produces electricity from the ………………….. in it.

Answer

Answer: chemicals stored

3. In an electric circuit a fuse is a ………………….. to prevent possible fire.

Answer

Answer: safety device

4. A combination of two or more cells is called a ………………….. .

Answer

Answer: battery

5. The coil of wire in an electric heater is called an ………………….. .

Answer

Answer: element

6. A ………………….. is a safety device which prevents damages to electrical circuits and possible fires.

Answer

Answer: fuse

7. The wire gets ………………….. when an electric current passes through it.

Answer

Answer: hot

8. We must look for ………………….. mark on electrical appliances.

Answer

Answer: ISI

9. When electric current passes through a wire, it behaves like a magnet. It is the ………………….. effect of current.

Answer

Answer: magnetic

10. Crane has a strong ………………….. attached to it.

Answer

Answer: electromagnet

Choose the true and false statements from the following:

1. It is convenient to represent electric components by symbols.

Answer

Answer: True

2. A connecting wire is symbolized by a zig-zag line in the circuit diagram.

Answer

Answer: False

3. When an electric current flows through a wire, the wire gets heated.

Answer

Answer: True

4. The key or switch can be placed anywhere in the circuit.

Answer

Answer: True

5. The amount of heat produced in a wire depends on its material, length and thickness.

Answer

Answer: True

6. CFLs consume more electricity than ordinary bulbs.

Answer

Answer: False

7. For different requirements, the wires of different materials, different lengths and thicknesses are used.

Answer

Answer: True

8. A fuse is used to save energy in electrical circuits.

Answer

Answer: False

9. MCBs are the switches which automatically turn off when current in a circuit exceeds the safe limit.

Answer

Answer: True

10. When an electric current flows through a wire, it behaves like a magnet.

Answer

Answer: True

Question 1.
Mention the name of the two devices that work on the basis of magnetic effects of current.
Answer:
The devices that work on the basis of magnetic effects of current are loudspeaker and electric bell.

Question 2.
Name the device used these days in place of eiectric fuses in electrical circuits.
Answer:
The device used in these days in place of electric fuse is MCB (Miniature Circuit Breaker).

Question 3.
State the property of a conducting wire is utilised in making electric fuse. INCERT Exemplar]
Answer:
Electric fuse wire is made up of special material which has low melting point. As if high amount of current is passed, it melts to disconnect the electric circuit and prevent us from causing any damage.

Question 4.
Explain why are CFLs (Compact Fluorescent Lamps) preferred over electric bulbs. [NCERT Exemplar; HOTS]
Answer:
Compact fluorescent lamps are preferred over electric bulbs because electric bulbs use more power of electricity and it also losses electrical energy in the form of heat but it is not so in compact fluorescent lamps.

Question 5.
Name the type of mark for which we should look at an electrical appliance before buying, [HOTS]
Answer:
ISI mark is a mark for which we should look at an electrical appliance before buying.

Question 6.
Briefly mention which part of the symbol of battery shows positive and negative terminals?
Answer:

The positive terminal is represented by longer vertical line while negative terminal is represented by shorter vertical line.

Question 7.
Briefly state the effects of electricity.
Answer:
The three effects of electricity are

Chemical effect
Heating effect
Magnetic effect

Question 8.
When does a circuit is said to be overloaded?
Answer:
It is overloaded by connecting too many devices to it. When too many devices get connected, then a circuit is said to be overloaded.

Question 9.
Why is an electric fuse required in all electrical appliance? [NCERT Exemplar]
Answer:
Electric fuse is required in all electrical appliances to prevent damage from excessive current flow and during short circuit.

Question 10.
Give the name any two electrical appliances in which electromagnets are used.
Answer:
Electric fan and electrical motor are the electrical appliances in which electromagnets are used.

Question 11.
Paheli does not have a night lamp in her room. She covered the bulb of her room with a towel in the night to get dim light. Has she taken the right step? Give one reason to justify your answer. [NCERT Exemplar; HOTS]
Answer:
No, she has not taken the right step. Because due to excessive heat of bulb, the towel may burn and it also results in the wastage of electrical energy.

Question 12.
The nails attract the pins. Comment.
Answer:
When the current is passed through the wire wound on the nail, it behave as electromagnet. Due to this reason, the nails attract the pins.

Question 13.
Name the scientist who discovered the magnetic effect of electric current.
Answer:
The scientist who discovered the magnetic effect of electric current is Hans Christian Oersted.

Question 14.
If the filament of the bulb is broken, would the circuit be complete? Would the bulb still glow?
Answer:
If the filament of the bulb is broken, the circuit will not be complete.
So, the bulb will not glow.

Question 15.
Name some electric appliances where the heating effect of the electric current is used.
Answer:
Some of the electric appliances where the heating effect of the electric current is used are electric heater, geyser, micro-oven, room heater, boiler, etc.

Question 16.
If the current through the coil stops flowing. Will the coil remain an electromagnet?
Answer:
When the current through the coil stops flowing, the coil does not remain an electromagnet.

Question 17.
State whether the bulb glows when the circuit is opened.
Answer:
No, the bulb does not glow when the circuit is opened. The bulb glows only when the circuit is closed.

Question 18.
What happens to the current in a circuit at the time of short circuit?
Answer:
The value of the current in a circuit increases heavily at the time of short circuit.

Question 19.
We should not touch the lighted bulb. Explain, why.
Answer:
The lighted bulb connected to main supply should not be touched by our hand directly, as a lighted bulb can be very hot and can burn our hand as well.

Electric Current and Its Effects Class 7 Science Extra Questions Short Answer Type Questions

Question 1.
Name two electric devices for each where
(a) heating effect of current is used and
(b) magnetic effect of current is used. [NCERT Exemplar]
Answer:
(a) Heating effect of current is used in electric heater and geyser.
(b) Magnetic effect of current is used in electric bell and cranes to lift heavy magnetic materials from one place to other.

Question 2.
Why do we cover plug pinholes which are within the reach of children with cellotape or a plastic cover when not in use? [NCERT Exemplar; HOTS]
Answer:
We do cover plug pinholes which are within the reach of children with cellotape or plastic cover to avoid electric shocks. If unconsciously, a child puts his finger in the electric socket, the shock may be fatal.

Question 3.
Can we use the same fuse in a geyser and a television set? Explain. [NCERT Exemplar; HOTS]
Answer:
No, we cannot use same fuse in a geyser and in a television set because the fuse used in every appliances has some limit to withstand the current flows through it. So, different appliances have different fuses.

Question 4.
If cells are placed side by side. Then, how are the terminals of the cells connected?
Answer:
If cells are placed side by side, then with the help of some connecting wires, the positive terminal of one cell is connected to the negative terminal of other to produce a combined power of all cells which can be called a battery.

Question 5.
Explain how a battery can be constructed.
Answer:
As we know that a battery is a combination of two or more cells and it can be constructed by placing cells property on cell holder in such a way that the positive terminal of one cell is connected to the negative terminal of other.
A piece of wire is connected to each of the two metal clips on the cells holder.

Question 6.
Distinguish between an open circuit and a closed circuit.
Answer:
Difference between an open circuit and a closed circuit

Open (Electric) circuit	Closed (Electric) circuit
An open electric circuit is or electric path which begins from the positive terminal of a battery or cell, gets broken at some point.	A closed circuit is an electric path which begins from the positive terminal of a cell or battery and terminates at its negative terminal without any break.

Question 7.
Boojho made an electromagnet by winding 50 turns of wire over an iron screw. Paheli also made an electromagnet by winding 100 turns over a similar iron screw. Which electromagnet will attract more pins? Give reason. [NCERT Exemplar; HOTS]
Answer:
Since the magnetic effect directly depends on the number of turns of the coil. As, Paheli’s coil has more number of turns than Boojho. So, her electromagnet is stronger than Boojho.
So, electromagnet of Paheli attracts more pins as compared to Boojho.

Question 8.
Does the electric current have other effect except heating? Name it.
Answer:
Yes, electric current have other effect except heating, i.e. magnetic effect of current.
When electric current is passed through a coil, there is a magnetic field developed around the coil or wire, if magnetic compass is placed near by, it deflects the magnetic needle.

Question 9.
Explain the following.
(a) Copper and aluminium wires are usually employed for electricity transmission. Explain the reason.
(b) Explain how does the resistance of a wire vary with its length.
(c) The tungsten is used almost exclusively for filament of electric lamp. Comment.
Answer:
(a) Due to the low resistance and strength of aluminium and coppers, both these metals are usually employed for the transmission of electricity.
(b) There is always an increase in the length of the wire with the increase in its resistance.
(c) Since tungsten has high melting point and high resistance. So, that is why, the tungsten is used exclusively for filament of electric lamp.

Question 10.
If we connect more cells in the circuit, then what will happen?
Answer:
If we connect more of cells in the circuit, then the nail will attract more pins. It is due to the reason that the current flowing through the wire wound on the nail will get increase which in turn will increase the strength of the electromagnet.

Question 11.
Electromagnets are better than permanent magnets. Explain why.
Answer:
An electromagnet can be switched OFF or switched ON as desired and this is not possible in the permanent magnets. That is why the electromagnets are better than the permanent magnets.

Question 12.
If the current flows through wire, does the wire behave like a magnet?
Answer:
When the current flows through any wire, a magnetic field is developed around that wire or coil and it behaves like magnet. It can be analysed by placing a magnetic compass around the wire, it will show deflection of the needle.

Question 13.
If current is passed through a coil, does the pins cling to the coil?
Answer:
When an electric current is passed through a coil, it gets magnetised due to phenomena of magnetic effect of current. When magnetic materials such as pins are placed near to it. It gets attracted by the coil or we can say that pins cling to the coil.

Question 14.
Batteries used in tractors, trucks and inverters are also made from cells. Then why it is called a battery? [HOTS]
Answer:
The cell is the unit of battery when more than one cell are combined together, it forms a battery. In trucks, tractors and inverters, cells are internally arranged and we need not to connect it externally, so we called it as batteries.

Electric Current and Its Effects Class 7 Science Extra Questions Long Answer Type Questions

Question 1.
One day, Pinki was ironing the clothes in her room. After half an iron of ironing, the light went off and Pinki went outside to the lobby of her house to check it there was any problem in the household circuit. At the same time, she listened the voice of her 4 years old daughter from the same room where she was ironing the clothes. Her daughter was about to touch the hot electric iron but at the same moment, Pinki entered in the room and pushed her daughter back from that place.
(a) On which effect of electric current, does the electric iron works?
(b) Mention the values showed by Pinki here. [Value Based Question]
Answer:
(a) The electric iron works on the basis of heating effect of electric current.
(b) The values showed by Pinki here is a great concern and love towards her own 4 years old daughter.

Question 2.
Explain with the help of a diagram, how does the magnetic effect of electric current help in the working of an electric bell.
Answer:
In order to ring the bell first of all we press the push button switch in order to ring the bell. So, when we press the switch, then the electric circuit of the bell is completed and a current passes through the coil of the electromagnet and it gets magnetised. The electromagnet attracts the iron armature towards itself.

So, as the armature moves towards the poles of the electromagnet, the clapper attached to it strikes the gong and produces a ringing sound. It implies that the bell rings.

When the armature moves towards the magnet, its contact with the contact screw is broken. Due to this, the electric circuit breaks and no current flows in the electromagnet coil. The electromagnet loses its magnetism for a moment and the armature is no longer attracted by it. The flat spring brings back the iron armature to its original position and the clapper also moves away from the gong.

As soon as the armature comes back and touches the contact screw the circuit is completed and current starts flowing in the electromagnet coil again. The electromagnet attracts the iron armature once again and the clapper strikes the gong again producing a ringing sound.

So, this process of ‘make and break’ of the electric circuit continues as long as we are pressing the switch. Due to this, the armature vibrates forwards and backwards rapidly each time making the clapper strike the gong. Thus, the clapper strikes the gong rapidly producing almost continuous sound.

Question 3.
State one measure to avoid overloading in an electrical circuit. Also mention the name given to a situation in which the live and the neutral wires accidently come in contact. Describe the role of a safety device in this situation.
Answer:
Overloading can be avoided if too many appliances are not connected to a single socket. Short circuiting is a name given to a situation in which the live and the neutral wires accidently come in contact.

Electric fuse is a safety device. When a short circuit takes place or when overloading takes place, then the current becomes large and heats the fuse wire too much and thus, it gets melted and circuit breaks which prevents the damage of the wiring and electrical appliances.

Question 4.
Paheli took a wire of length 10 cm. Boojho took a wire of 5 cm of the same material and thickness both of them connected with wires as shown in the circuit given in figure. The current flowing in both the circuits is the same.
(a) Will the heat produced in both the cases be equal? Explain.
(b) Will the heat produced be the same, if the wires taken by them are of equal lengths but of different thickness? Explain.

Answer:
(a) No, the amount of heat produced in both the wires will be different because amount of heat produced in a wire on passing electric current depends on the length of wire and here length is different for both the wires.
(b) No, the amount of heat produced in the wire of same length but different thickness cannot be same because amount of heat produced in a wire also depends on the thickness of the wire.

Question 5.
Last Sunday, Pulpit was playing videotape in his room. While playing, the electricity of his house went off due to which he could not able to see anything around him. Then anyhow, he managed to get his mobile in his hand and with the help of its light, he went outside of his room to check if there was any problem in the electric circuit board of his house.
At the same time, his father suggested him to maintain the distance from the circuit board and decided to call some electrician to check the problem.
(a) Explain, what happens when live wire and neutral wire touches each other directly?
(b) State the values here showed by Pulkit’s father. [Value Bated Question]
Answer:
(a) When live and neutral wire touches each other directly then it leads to short circuit in which the large amount of current flows through the household wiring and this large current may heat the wires to a dangerously high temperature and a fire may be started.
(b) Pulkit’s father seems very sensible in taking the decisions and he showed a very great concern towards his son

Rohit0 comments

CHAPTER – 13 Motion and Time | CLASS 7TH | NCERT SCIENCE IMPORTANT QUESTIONS & MCQS | EDUGROWN

SCIENCE IMPORTANT QUESTIONS & MCQS FOR CLASS 7th

Chapter - 13 Motion and Time

Question 1.
A bus travels 54 km in 90 minutes. The speed of the bus is
(a) 0.6 m/s
(b) 10 m/s
(c) 5.4 m/s
(d) 3.6 m/s

Answer

Answer: (b) 10 m/s

Question 2.
If we denote speed by S, distance by D and time by T, the relationship between these quantities is
(a) S = D T
(b) T = SD
(c) S = 1T × D
(d) S = TD

Answer

Answer: (c) S = 1T × D

Question 3.
Observe the figure given below:
MCQ Questions for Class 7 Science Chapter 13 Motion and Time with Answers 1
The time period of a simple pendulum is the time taken by it to travel from
(a) A to B and back to A
(b) O to A, A to B and B to A
(c) B to A, A to B and B to O
(d) A to B

Answer

Answer: (a) A to B and back to A

Question 4.
Nearly all the clocks make use of
(a) straight line motion
(b) periodic motion
(c) random motion
(d) circular motion

Answer

Answer: (b) periodic motion

Question 5.
A simple pendulum takes 42 sec. to complete 20 oscillations. What is its time period?
(a) 2.1 s
(b) 4.2 s
(c) 21 s
(d) 8.40 s

Answer

Answer: (a) 2.1 s

Question 6.
Time period of a simple pendulum depends upon its
(a) weight of bob
(b) length
(c) both (a) and (b)
(d) None of these

Answer

Answer: (b) length

Question 7.
Which of the following cannot be used for measurement of time?
(a) A leaking tap
(b) Simple pendulum
(c) Shadow of an object during the day
(d) Blinking of eyes

Answer

Answer: (d) Blinking of eyes

Question 8.
On which axis is dependent variable represented?
(a) x-axis
(b) y-axis
(c) On any axis
(d) Depends on the data

Answer

Answer: (b) y-axis

Question 9.
The correct symbol to represent the speed of an object is:
(a) 5 m/s
(b) 5 mp
(c) 5 m/s^-1
(d) 5 s/m

Answer

Answer: (d) 5 s/m

Question 10.
Boojho walks to his school which is at a distance of 3 km from his home in 30 minutes. On reaching he finds that the school is closed and comes back by a bicycle with his friend and reaches home in 20 minutes. His average speed in km/h is
(a) 8.3
(b) 7.2
(c) 5
(d) 3.6

Answer

Answer: (b) 7.2

Match the following:

Column A	Column B
(i) Years	(a) Rotation period of earth on its axis
(ii) Hour	(b) Time to complete 100 m race
(iii) Minute	(c) Gestation period in humans
(iv) Days	(d) Age of a person
(v) Second	(e) In scientific research
(vi) Month	(f) Age of stars
(vii) Microseconds	(g) Time to reach your school
	(h) Train reaches from one city to other

Answer

Answer:

Column A	Column B
(i) Years	(d) Age of a person
(ii) Hour	(h) Train reaches from one city to other
(iii) Minute	(g) Time to reach your school
(iv) Days	(a) Rotation period of earth on its axis
(v) Second	(b) Time to complete 100 m race
(vi) Month	(c) Gestation period in humans
(vii) Microseconds	(e) In scientific research

Fill in the blanks:

1. The distance covered by an object in a ………………… is called its speed.

Answer

Answer: unit time

2. Time between one sunrise and the next sunrise was called a …………………

Answer

Answer: day

3. In a simple pendulum, the metallic ball suspended by thread is called its …………………

Answer

Answer: bob

4. Time period of a pendulum depends on its …………………

Answer

Answer: length

5. The symbols of all units are written in …………………

Answer

Answer: singular

6. A ………………… is one billionth of a second.

Answer

Answer: nanosecond

7. Motion of objects can be presented in pictorial form by their ………………… graph.

Answer

Answer: distance time

8. The distance-time graph for the motion of an object moving with a constant speed is a …………………

Answer

Answer: straight line

Choose the true and false statements from the following:

1. Faster vehicle has a higher speed.

Answer

Answer: True

2. All the clocks make use of some periodic motion.

Answer

Answer: True

3. The basic unit of speed is km/h.

Answer

Answer: False

4. The symbols of all units are written in singular.

Answer

Answer: True

5. The basic unit of time is second.

Answer

Answer: True

6. Age of a person is expressed in days.

Answer

Answer: False

7. The distance-time graph of standing vehicle is a straight line parallel to x-axis.

Answer

8. Periodic events are used for the measurement of time.

Answer

Question 1.
Give the basic unit of speed.
Answer:
Metre/second is the basic unit of speed.

Question 2.
Mention which is the most common thing in almost all the clocks.
Answer:
The most common thing in almost all the clocks is that all of them shows periodic motion.

Question 3.
Paheli and Boojho have to cover different distances to reach their school but they take the same time to reach the school. What can you say about their speed? [NCERT Exemplar; HOTS]
Answer:
They do not have equal speed because they cover unequal distance in equal intervals of time. One of them has higher speed whom has to cover larger distance with respect to other.

Question 4.
If Boojho covers a certain distance in one hour and Paheli covers the same distance in two hours, who travels with a higher speed? [NCERT Exemplar; HOTS]
Answer:
Boojho travels with a higher speed as he has covered same distance in lesser time with respect to Paheli.

Question 5.
A simple pendulum is oscillating between two points A and B as shown in figure. Is the motion of the bob uniform or non-uniform?
Motion and Time Class 7 Extra Questions Science Chapter 13 1
Answer:
The motion of bob is non-uniform as it does not cover equal distance in equal intervals of time.

Question 6.
State the characteristic of distance-time graph for the motion of an object moving with a constant speed.
Answer:
The distance-time graph for the motion of an object moving with a constant speed is a straight line inclined on x-axis at some angles.

Question 7.
Name the axis that represents dependent variable.
Answer:
y-axis represents the dependent variable.

Question 8.
Briefly explain how will decide which object is moving fast and which one is moving slow.
Answer:
If an object covers more distance in equal intervals of time with respect to other, then we can say that object is moving faster with respect to the other object.

Question 9.
If you did not have a clock, how would you decide what time of the day is? [HOTS]
Answer:
We can decide time of the day without clock by seeing shadow formed by the sun, e.g. at noon, shadow formed by the sun is shorter than at evening.

Question 10.
State how do we measure time interval of a month.
Answer:
Time interval of a month is measured by one new moon to the next.

Question 11.
Determine the number of seconds there in a day.
Answer:
In a day, we have 24 h
We know that 1 h = 3600 s
So, 24 h = 3600 × 24 = 86400s

Question 12.
Estimate that how many hours are there in a year.
Answer:
In a year, we have 365 days and 1 day = 24 h
So, for 365 days, we have 24 × 365 h = 8760 h

Question 13.
Explain how time was measured when pendulum clocks were not available.
Answer:
Before the discovery of pendulum clocks, sundials, water clocks and sand clocks were used.

Question 14.
A spaceship travels 36000 km in one hour.Express its speed in km/s.
Answer:
Motion and Time Class 7 Extra Questions Science Chapter 13 2

Question 15.
Out of the two given clocks, a pendulum clock or a quartz clock. Mention which of the clock between the given ones requires an electric cell for its working?
Answer:
A quartz clock requires an electric cell for its working.

Question 16.
Name the most ancient unit of time in which it was earlier measured.
Answer:
Solar day is the most ancient unit of time in which it was earlier measured.

Question 17.
State the condition under which the distance-time graph of an object is a horizontal line parallel to the axis of time.
Answer:
When the object is at rest, then the distance-time graph of an object is a horizontal line parallel to the axis of time.

Question 18.
State the factors on which the time period of a simple pendulum depend.
Answer:
The factors on which the time period of a simple pendulum depend are

Length of the pendulum
Acceleration due to gravity.

Question 19.
Name the different types of graphs.
Answer:
Different types of graphs are

Line graph
Pie chart
Bar graph

Question 20.
State the way through which we can prepare a pendulum by our own.
Answer:
By suspending a metal ball with the help of a cotton thread and the other end of the thread can be tied to some different supports, so in this way, we can prepare a pendulum by our own.

Motion and Time Class 7 Science Extra Questions Short Answer Type Questions

Question 1.
Last Sunday, Priyanka decided to go outside with her family for the dinner in some particular restaurant.
Then, she thought to go through her own car. So, while moving she increased the speed of the car from 36 km/h to 54 km/h. All of sudden, a rickshaw came in front of her car but due to applying of brakes at the right time, both of them got safe from meeting with an accident. [Value Based Question]
(a) Calculate the increase in the speed of the car in the terms of m/s.
(b) Mention a positive action performed by Priyanka here.
Answer:
Motion and Time Class 7 Extra Questions Science Chapter 13 3
∴ Increase in speed = Final speed – Initial speed =(15-10) m/s = 5 m/s
(b) Priyanka applied the brakes at a right time while driving the car and prevented her family and the person on rickshaw from meeting with an accident.

Question 2.
Differentiate between a uniform and non-uniform motion.
Answer:
When a body travels equal distance in an equal interval of time, then the body is said to be in a uniform motion.
When a body travels unequal distance in an equal interval of time, then the body is said to be in non-uniform motion.

Question 3.
Briefly mention how many types of motion are there. Also, name all of them.
Answer:
Different types of motion are there and they can be named as follows

Periodic motion
Rolling motion
Rotatory motion
Oscillatory and vibratory motions
Translatory motion

Question 4.
The average age of children of class VII is 12 years and 3 months. Express this age in second. [NCERT Exemplar]
Answer:
Given, the average age of children 12 years and 3 months
1 year = 365 days = 365 × 24 h [1 day = 24 h]
= 365 × 24 × 3600 s [1 h = 3600 s]
12 years = 31536000 s × 12 = 378432000 s
3 months = 30x3days = 30 × 3 × 24h = 30 × 3 × 24 × 3600s = 7776000s
So, total age in second = 378432000 + 7776000 = 386208000s

Question 5.
Plot a distance-time graph of the tip of the second hand of a clock by selecting 4 points on X-axis and /-axis, respectively. The circumference of the circle traced by the second hand is 64 cm. [NCERT Exemplar]
Answer:

Time (s)	X	15	30	45	60
Distance (cm)	Y	16	32	48	64

As, here equal distance is covered in equal intervals of time.
So, graph will be straight line.
Motion and Time Class 7 Extra Questions Science Chapter 13 4

Question 6.
With the help of the data given in the following table, show graphically the relationship between the diameter and circumference of a circle.

Diameter of the circle (cm)	Circumference of the circle (cm)
1	3.2
2	6.3
3	9.4
4	12.6
5	15.7
6	18.8

Answer:
With the help of a given data in a tabular form, the graph can be obtained by taking diameter of the circle on the x-axis and the circumference on y-axis. On x-axis, 1 cm diameter is shown by 1 cm and on the y-axis, 3 cm of circumference is shown by 1 cm.
Motion and Time Class 7 Extra Questions Science Chapter 13 5

Question 7.
Starting from A, Paheli moves along a rectangular path ABCD as shown in figure. She takes 2 min to travel each side. Plot a distance-time graph and explain whether the motion is uniform or non-uniform.
Motion and Time Class 7 Extra Questions Science Chapter 13 6
Answer:
Since, the distance covered per unit time for the entire distance covered is not the same, the motion is a non-uniform motion.

Question 8.
One day, a five years old boy, Chintoo was playing with his toys in his room. After few minutes, he saw a wristwatch on his study table, so after seeing it, he got crazy and so much in eager to play with that watch. Then, for 2 to 3 min, he was trying to analyse it that whether its a toy or something else, then suddenly, he was just about to throw it but at the same his mother entered into the room and take the watch back immediately from his hand.
(a) State the benefit of a wristwatch.
(b) Briefly mention the values showed by Chintoo’s mother here. [Value Based Question]
Answer:
(a) The wristwatch can be handled very easily to check the time in comparison to the wall clock.
(b) The values showed by Chintoo’s mother here is the concern towards her four years old child and also the concern towards that wristwatch while considering the importance of money.

Question 9.
The following distance-time graph of three objects (D, E and F) are given (see figure given alongside). What can you say about the motion of the objects?
Motion and Time Class 7 Extra Questions Science Chapter 13 8
Answer:
Since, the distance-time graph of an object D is a straight line therefore, its motion is uniform. Also here, we can see that the distance-time graph of object E is parallel to x-axis (time-axis), therefore object E is at rest.
As, the distance-time graph of object F is a curved line, therefore the object C is moving with a non-uniform speed and its motion is non-uniform.

Question 10.
The following figure shows the distance-time graph for the motion of two objects D and E. Which one of them is moving slower?
Motion and Time Class 7 Extra Questions Science Chapter 13 9
Answer:
After studying the figure given alongside, D or E is moving slower as the slope of distance-time graph of E is less than that of graph D.

Question 11.
The following figure shows the distance-time graph for the motion of two vehicles (C and D). At what time and distance (from the starting point), they will cross each other.
Answer:
Firstly, draw perpendicular lines from point E on x-axis and y-axis.
Motion and Time Class 7 Extra Questions Science Chapter 13 10
The two vehicles (C and D) will meet (or cross) each other at 5:00 PM and after travelling a distance of 4 km.

Motion and Time Class 7 Science Extra Questions Long Answer Type Questions

Question 1.
Given below as a figure is the distance-time graph of the motion of
(a) What will be the position of the object at 20 s?
(b) What will be the distance travelled by the object in 12 s?
(c) What is the average speed ofthe object? [NCERT Exemplar]
Motion and Time Class 7 Extra Questions Science Chapter 13 11
Answer:
(a) From the graph, it is clear that the distance at 20 s is 8 m.
(b) Distance travelled by the body object in 12 s is 6 m.
(c) As, average speed = Total distance Total time =820=0.4m/s

Question 2.
Boojho goes to the football ground to play football. The distance-time graph of his journey from his home to the ground is given as figure. [NCERT Exemplar]
(a) What does the graph between points B and C indicate about the motion of Boojho?
(b) Is the motion between 0 to 4 min uniform or non-uniform?
(c) What is his speed between 8 to 12 min of his journey?
Answer:
(a) Since, the graph between B and C is parallel to time-axis, so it indicates that Boojho is at rest.
(b) Since, the graph is not straight line, so it is a non-uniform motion.
(c) As, speed = Distance Time =225−15012−8=754=18.75m/min

Question 3.
Explain by giving example that how can we choose a suitable scale.
Answer:
While choosing the most suitable scale for drawing a graph, we should keep the following points in mind
(i) The difference between the highest and lowest values of each quantity.
(ii) The intermediate values of each quantity so that with the scale chosen, it is easy to mark the values on the graph.
(iii) To utilise the maximum part of the paper on which the graph is to be drawn, assume that we have a graph paper of size 25 cm x 25 cm and we have to accommodate following data:

Time (AM)	Odometer reading	Distance from the starting point
8:00 AM	36540 km	0 km
8:30 AM	36560 km	20 km
9:00 AM	36580 km	40 km
9:30 AM	36600 km	60 km
10:00 AM	36620 km	80 km

Since, one of the scales will be
Distance 5 km = 1 cm and Time 6 min = 1 cm
Motion and Time Class 7 Extra Questions Science Chapter 13 12

Question 4.
Distance between Bholu’s and Golu’s house is 9 km. Bholu has to attend Golu’s birthday party at 7 O’ clock. He started his journey from his home at 6 O’ clock on his bicycle and covered a distance of 6 km in 40 min. At that point, he met Chintu and he spoke to him for 5 min and reached Golu’s birthday party at 7 O’ clock. With what speed, did he cover the second part of the journey? Calculate-his average speed for the entire journey. [NCERT Exemplar]
Answer:
From the question, Bholu covers 3 km distance in 15 min.
Motion and Time Class 7 Extra Questions Science Chapter 13 13

Question 5.
The given data regarding the motion of two different objects C and D is in a tabular form. Check them carefully and state whether the motion of the objects is uniform or non-uniform.

Time	Distance travelled by C (in m)	Distance travelled by D (in m)
9:30 AM	10	12
9:45 AM	20	19
10:00 AM	30	23
10:15 AM	40	35
10:30 AM	50	37
10:45 AM	60	41
11:00 AM	70	44

Answer:
We can check the motion of the objects C and D by plotting the distance-time graph for the two objects.
Motion and Time Class 7 Extra Questions Science Chapter 13 14
Graph the object C on x-axis
Scale 1 cm = 15 min and on y-axis 1 cm = 10 m
Since, the distance-time graph of the object C is a straight line. Therefore, its motion is uniform.
Graph of object D
Scale On x-axis, 1 cm = 15 min, On y-axis 1 cm=5m
Motion and Time Class 7 Extra Questions Science Chapter 13 15
Since, the distance-time graph of the object D is not a straight line, therefore, its motion is non-uniform.

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CHAPTER – 12 Reproduction in Plants | CLASS 7TH | NCERT SCIENCE IMPORTANT QUESTIONS & MCQS | EDUGROWN

SCIENCE IMPORTANT QUESTIONS & MCQS FOR CLASS 7th

Chapter - 12 Reproduction in Plants

MCQs

Question 1.
Vegetative propagation in potato takes place by
(a) leaves
(b) stem
(c) root
(d) seed

Answer

Answer: (b) stem

Question 2.
In which of the following plants buds are present on the margins of leaves?
(a) Bryophyllum
(b) Touch me not
(c) Chandan
(d) Coriander

Answer

Answer: (a) Bryophyllum

Question 3.
In yeasts reproduction occurs by
(a) fragmentation
(b) binary fission
(c) budding
(d) spore formation

Answer

Answer: (c) budding

Question 4.
Which of the following parts of a plant take part in sexual reproduction?
(i) Flower
(ii) Seed
(iii) Fruit
(iv) Branch
Choose the correct answer from below:
(a) (i) and (ii)
(b) (i), (ii) and (iii)
(c) (iii) and (iv)
(d) (ii), (iii) and (iv)

Answer

Answer: (b) (i), (ii) and (iii)

Question 5.
Lila observed that a pond with clear water was covered up with a green algae within a week. By which method of reproduction did the algae spread so rapidly ?
(a) Budding
(b) Sexual reproduction
(c) Fragmentation
(d) Pollination

Answer

Answer: (c) Fragmentation

Question 6.
Seeds of drumstick and maple are carried to long distances by wind because they possess
(a) winged seeds
(b) large and hairy seeds
(c) long and ridged fruits
(d) spiny seeds

Answer

Answer: (a) winged seeds

Question 7.
The ‘eye of the potato plant is what
(a) the root is to any plant
(b) the bud is to a flower
(c) the bud is to Bryophyllum leaf
(d) the anther is to stamen

Answer

Answer: (c) the bud is to Bryophyllum leaf

Question 8.
The ovaries of different flowers may contain
(a) only one ovule
(b) many ovules
(c) one to many ovules
(d) only two ovules

Answer

Answer: (c) one to many ovules

Question 9.
Which of the following statements is/are true for sexual reproduction in plants?
(i) Plants are obtained from seeds
(ii) Two plants are always essential
(iii) Fertilisation can occur only after pollination
(iv) Only insects are agents of pollination
Choose from the options given below:
(a) (i) and (ii)
(b) (i) only
(c) (i) and (ii)
(d) (i) and (iv)

Answer

Answer: (a) (i) and (ii)

Question 10.
Pollination refers to the:
(a) transfer of pollen from anther to ovary
(b) transfer of male gametes from anther to stigma
(c) transfer of pollen from anther to stigma
(d) transfer of pollen from anther to ovule

Answer

Answer: (c) transfer of pollen from anther to stigma

Match the following:

Column A	Column B
(i) Bread mould	(a) Cutting
(ii) Yeast	(b) Leaves
(iii) Potato	(c) Fragmentation
(iv) Bose	(d) Detached body part
(v) Sweet potato	(e) Spores
(vi) Bryophyllum	(f) Eye
(vii) Cactus	(g) Roots
(viii) Spirogyra	(h) Budding

Answer

Answer:

Column A	Column B
(i) Bread mould	(e) Spores
(ii) Yeast	(h) Budding
(iii) Potato	(f) Eye
(iv) Bose	(a) Cutting
(v) Sweet potato	(g) Roots
(vi) Bryophyllum	(b) Leaves
(vii) Cactus	(d) Detached body part
(viii) Spirogyra	(c) Fragmentation

Fill in the blanks:

1. In …………………. reproduction, one individual can produce many individuals from its body parts.

Answer

Answer: asexual

2. Both stamen and carpel are present in …………………. flowers.

Answer

Answer: bisexual

3. Budding is a type of …………………. reproduction.

Answer

Answer: asexual

4. The process of …………………. ensures continuity of life on the earth.

Answer

Answer: reproduction

5. …………………. are the reproductive parts of a plant.

Answer

Answer: Flowers

6. Buds in potato are also called ………………….

Answer

Answer: eyes

7. Plants produce seeds as a result of …………………. reproduction.

Answer

Answer: sexual

8. The small bulb like projection coming out from the yeast cell is called a ………………….

Answer

Answer: bud

9. The …………………. develops into an embryo.

Answer

Answer: zygote

10. The fruits are ripened ………………….

Answer

Answer: ovary

Choose the true and false statements from the following:

1. Two individuals are needed for a sexual reproduction.

Answer

Answer: True

2. Seed is the only structure which develops into new plant.

Answer

Answer: False

3. Plants such as cacti produce new plants when their parts get detached from the main plant body.

Answer

Answer: True

4. Plants produced by vegetative propagation take less time to grow and bear flower and fruit.

Answer

Answer: True

5. The spores are asexual reproductive bodies.

Answer

Answer: True

6. Anther contains female gametes called eggs.

Answer

Answer: False

7. The fruit is ripened ovary.

Answer

Answer: True

8. Seed dispersal in coconut is aided by winds.

Answer

Answer: False

9. Fusion of male and female gametes is called pollination.

Answer

Answer: False

10. A bisexual flower has both male and female reproductive parts.

Answer

Answer: True

Question 1.
Why is the process of reproduction necessary?
Answer:
The process of reproduction is necessary for the perpetuation and preservation of species and to increase the number of members of species.

Question 2.
If the filament of Spirogyra is broken into fragments. What will you observe?
Answer:
If the filament of Spirogyra are broken into fragments, then each fragment will develop into a new plant.

Question 3.
Fungus, moss and fern reproduce by a common method of asexual reproduction. Name the method. [NCERT Exemplar]
Answer:
Fungus, moss and fern reproduce by the common method of spore formation which is a type of asexual reproduction.

Question 4.
A flower consists of different parts. Name these parts of a flower.
Answer:
The four main parts of a flower are
(i) Sepals
(ii) Petals
(iii) Stamen
(iv) Pistil

Question 5.
Mention the mode of reproduction in the following plants
(a) Spirogyra
(b) Yeast
(c) Money plants
Answer:
(a) Spirogyra – fragmentation
(b) Yeast – budding
(c) Money plant – Vegetative propagation

Question 6.
Pick the odd one out from the following on the basis of mode of reproduction and give reason for it, Sugarcane, Potato, Rice, Rose. [NCERT Exemplar]
Answer:
The odd one out is rice.
In the above given pairs as rice reproduces by sexual reproduction and sugarcane, potato and rose reproduces vegetatively.

Question 7.
Give one difference between unisexual and bisexual flower.
Answer:
Unisexual flowers are those which contain either male or female reproductive part and bisexual flower has both reproductive parts (i.e. male and female) on the same flower.

Question 8.
Flowers are colourful and fragrant. Give reason supporting the statement. [HOTS]
Answer:
Flowers are so colourful because they absorb and reflect light energy. Fragrance results from production of volatile chemicals which evaporate.

Question 9.
Boojho had the following parts of a rose plant-a leaf, roots, a branch, a flower, a bud and pollen grains. Which of them can be used to grow a new rose plant? [NCERT Exemplar]
Answer:
Branch can be used to grow a new rose plant. As, rose reproduces by vegetative propagation, i.e. stem cutting method.

Question 10.
Formation of new but similar individuals from parents is characteristic feature of which process?
Answer:
Reproduction is the process of production of new similar organisms from their parents.

Question 11.
Name two plants where vegetative reproduction takes place by roots.
Answer:
Sweet potato and dahlia develops new plants through their roots by the process of vegetative reproduction.

Question 12.
A yellow powdery substance is present in the anther which participates in reproduction process. Name this substance.
Answer:
Pollen grains.

Question 13.
In which part of flower does fertilisation occur?
Answer:
Ovary is the part where male and female gametes fuse together.

Question 14.
Bryophyllum leaves reproduce using which mode of reproduction?
Answer:
Asexually by vegetative propagation.

Question 15.
Which type of pollination does the given figure indicate?

Answer:
The given figure shows self-pollination, as the pollen grains from anther of flower are transferred to the stigma of same flower.

Question 16.
What are the bulb-like projections forming in yeasts?
Answer:
The bulb-like projections formed during reproduction are called buds.

Question 17.
‘Spores’ as a means of asexual reproduction are used by which plants?
Answer:
Spores are produced by fungi, ferns and mosses during unfavourable conditions.

Question 18.
Write the male and female reproductive parts present on the flowers.
Answer:
The male reproductive part is stamen and the female reproductive part is pistil.

Question 19.
Pollen grains are present inside anthers for long time yet they do not die. Why?
Answer:
Pollen grains have a tough protective coat which presents them from drying up.

Question 20.
Name two plants in which pollination occurs by water.
Answer:
Vallisneria and Hydrilla.

Question 21.
Fruit is the ripened ovary of a flower. Explain.
Answer:
After fertilisation, the ovary of a flower develops and becomes a fruit with seeds present inside.

Question 22.
Banana is a fruit without seeds. Give reason.
Answer:
Banana forms from one parent only. There is no seed production.

Reproduction in Plants Class 7 Science Extra Questions Short Answer Type Questions

Question 1.
When you keep food items like bread and fruits outside for a long time especially during the rainy season, you will observe a cottony growth on them. [NCERT Exemplar; HOTS]
(a) What is this growth called?
(b) How does the growth take place?
Answer:
(a) When food items like bread and fruits are kept outside for a long time especially during rainy season, a cottony growth of bread mould, a fungus is observed.
(b) This growth of fungus takes place by spores present in air, which when comes in the contact with moisture in bread germinates and grow to produce new cells.

Question 2.
Collect some flower of different plants like papaya, rose, mustard, lady’s finger, Petunia, cucumber, corn, pea, etc. Group them under following heads.
(a) Which of these plants have unisexual flowers?
(b) Which of these plants have bisexual flower?
(c) What is the other name of unisexual and bisexual flower? [HOTS]
Answer:
(a) Unisexual flowers are papaya, cucumber, com.
(b) Bisexual flowers are rose, mustard, lady’s finger, Petunia, pea.
(c) Unisexual flowers are also called as incomplete flower while bisexual flowers are called hermaphrodite or complete flowers.

Question 3.
In the figure given below, label the part marked (i), (ii) and (iii). [NCERT Exemplar]

Answer:
The parts in the given figure are labelled as follows

Question 4.
Coconut is a large and heavy fruit. How is it adapted for dispersal by water? [NCERT Exemplar]
Answer:
The seeds of some plants that have an outer fibrous or spongy covering are dispersed through water. They have the ability to float in the water and drift along with its flow, e.g. seeds of water lily, lotus, chestnut (singhara) and coconut are dispersed through water. The coconut fruits have a fibrous outer coat which enables them to float in water and carried away by flowing water to far off places.

Question 5.
What is a bud? Which organism reproduce by budding? Given the diagrammatic representation of budding in a plant.
Answer:
Buds are small bulb-like projections of yeast cell.
These are asexual reproducing bodies of yeast.
Diagrammatic representation of budding in yeast Refer to figure on page 178.

Question 6.
Group the seeds given in figure (i) to (iii) according to their means of dispersion.
(a) Seed dispersed by wind.
(b) Seed dispersed by water.
(c) Seed dispersed by animal. [NCERT Exemplar]

Answer:
The seeds and their means of dispersal can be given as follows:
(a) The seed of maple is dispersed by wind. It has winged seed which are light in weight.

(b) Seed of aak or madar has hairy outgrowth which makes it lighter and can be dispersed by wind.

(c) Seed of Xanthium have numerous spines on them which gets attached to the fur of animals. Hence, these are dispersed by animals.

None of the seed given in the figure is dispersed by water

Question 7.
How does male gamete present in pollen grain reaches female gamete present in ovule?
Answer:
After pollination, the pollen grains fall on the surface of stigma and germinate to form a long tube, reaching the ovules inside the ovary, the egg or female gamete is present in the ovule.
The outer surface of pollen grains rupture and male gametes are released to fuse with egg.

Question 8.
How do the plants like sugarcane, potato and rose reproduce when they cannot produce seeds?
Answer:
Sugarcane and rose are propagated by stem cutting that is a method of vegetative propagation, in which stem is capable of growing into a mature independent plants that are identical to their parents.

Potato is an underground modified stem having bud called eyes, which sprout and develop into a new identical plant.
Thus, the plants which cannot produce seeds, can be propagated vegetatively with the help of vegetative parts such as stem, roots, buds and leaves.

Question 9.
Mention the benefits of seed dispersal.
Answer:
Benefits of Seed Dispersals

Seed dispersal avoids overcrowding of young plants around their parent plants.
It helps in preventing competition between the plants and its own seedlings for sunlight, water and minerals.
One of the benefits of seed dispersal is that it enables the plant to grow into new habitats for wider distribution and provides them with better chance of survival.

Question 10.
What is meant by the term fertilisation? List the stepwise manner leading to formation of an embryo.
Answer:

The process in which the male gamete fuses with female gamete to form a new cell (called zygote) is called fertilisation.
When the pollens are deposited on the stigma of the pistil, it begins to germinate. After sometime, a long pollen tube is developed from the pollen grain which passes through the style towards the female gametes in the ovary. The male gametes move down the pollen tube and the tube enters the ovule present inside the ovary.

The tip of pollen tube bursts and the male gamete comes out of the pollen tube. Inside the ovary, the male gametes fuse with the female gametes present in the ovule to form a fertilised egg cell which is called zygote.
The zygote develops into an embryo which is a part of a seed that develops into a new plant.

Question 11.
A student was given a flower. He was asked to pick the different whorls of flower by the forcep. He pulled each part of the flower and laid them on the chart paper in a sequence and named them W, X, Y, Z (from outer to inner whorl). He was unable to name them.
Help the student to name the different parts of a flower. Also help him to tell which part produces male gamete and female gametes. [HOTS]
Answer:
The four whorls of the flower are outermost whorl ‘W’ is green part which is called sepal. Inside sepal the next whorl is X which is coloured and attractive part of the flower called petals. The Y is the inner whorl of flower called stamen. It is the male reproductive part of flower. It consist of two parts, i.e. anther and filament. The anther contains male gametes called pollen grain. The whorl ‘Z’ is the innermost part of the flower called pistil. It is the female reproductive part of flower. It consist of three parts, i.e. stigma, style and ovary. The ovary produces ovule which contains the female gametes or egg cell.

Question 12.
One morning as Paheli strolled in her garden she noticed many small plants, which were not there a week ago. She wondered, where they had come from as nobody had planted them there. Explain the reason for the growth of these plants. [NCERT Exemplar; HOTS]
Answer:
The small plants which were not there in the garden a weak ago have grown up due to seed dispersal. The seeds from the tree may have fallen below or have been dispersed by wind or animals on the ground, which on germination developed into new small plants.

Question 13.
Place a piece of bread in a moist and warm place for few days. Observe it after few days. What will you see?
(a) Name the organism that grows on the bread piece?
(b) What are the thread-like projections called?
(c) What is the knob like structure present on the top of thin stem called?
(d) Which type of reproduction does this organism shows?
(e) From where does the spors comes to the bread piece? [HOTS]
Answer:
(a) When the bread piece is kept in a moist and warm place for few days, bread mould grows on the bread piece.
(b) The thread-like projections are called hyphae or mycelium.
(c) The thin stem having knob-like structure on the top is called sporangia or sporangium which contains hundred of minute spores.
(d) Bread mould shows asexual mode of reproduction.
(e) These spores are present in the air and when favourable conditions arrive, the grow into new plants.

Question 14.
Write how the following seeds are dispersed.
(a) Seeds with wings
(b) Small and light seeds.
(c) Seeds with spines/hooks.
Answer:
The mode of dispersal of the seeds having following properties are as follows:
(a) Seeds with wings-like seeds of drumstick and maple become light weighted and can be blown away by air. Thus, these are dispersed by wind.
(b) Small and light seeds like seeds of grasses and cotton (having hairy growth) are also dispersed through wind.
(c) Seeds of Xanthium, Urena have spines and hooks on them, these hooks or spines are attached to the fur of the animal body. When animals move to other places and rub their body with tree, etc., these seeds fall from their body and get dispersed.. Therefore, these are dispersed through animals.

Question 15.
Why is vegetative propagation a preferred method of asexual reproduction?
Answer:
The following advantages of vegetative reproduction makes it a preferred method

It takes less time to grow and bear flower and fruits than those produced from seeds.
The new plants are the exact copies of parent plant because they are produced from a single parent.

Question 16.
Insects are called agents of pollination. How do they aid in process of pollination?
Answer:
Flowers have nectars that attract insects. Insects suck these nectars as their food. When insects like bee, butterfly, etc., sit on the flower for sucking nectar, the sticky pollen grains get attached to their legs and wings. When these insects again sit on another flower, these pollen grains are transferred to the stigma of that flower from the body of the insects. In this way, insects help in pollination.

Question 17.
What is seed dispersal? What will happen if all the seeds of a plant were to fall at a same place and grow?
Answer:
Plant produces large number of seeds. When these seeds fall down they starts growing. The process by which the seeds are scattered to different place (far and wide from their parents) is called seed dispersal.
The seeds and fruits are dispersed away through various agencies like air, water and animals. Sometimes dispersal takes place by the explosion or bursting of fruits. If all the seeds of a plant were to fall at the same place and grow, there will be a severe competition for sunlight, water, mineral and space. As a result, the survival for the plants will be difficult and the plants who survive will not grow into a healthy plants.

Question 18.
Describe the structure of a flower.
Answer:
The main parts of a flower are

(i) Sepals These are the green leaf-like outermost circle of the flower. All the sepals are together referred to as calyx. The function of calyx is to protect the flower when it is in bud form.

(ii) Petals These are the colourful and most attractive part of flower. These lie inside the sepals. All the petals are together referred to as corolla. These are scented and attract insects for pollination.

(iii) Stamen It is a male reproductive organ of plant. These are the little stalks with swollen top and lies inside the ring of petals. The stamen is made up of two parts, i.e. filament and anther. The stalk of stamen is called filament and the swollen top of stamen is called anther.
Anther contains the pollen grain which have male gamete in it. Pollen grains are exposed when the anther ripens and splits. These appear as the yellow powder like substance which is sticky in nature. Flowers usually have a number of stamens in it.

(iv) Pistil It is the female reproductive part of a flower that lies in the centre of a flower. These are flask-shaped structure which is made up of three parts, i.e. stigma, style and ovary.
The top part of pistil is called stigma. It receives the pollen grains from the anther during pollination. The middle part of the pistil is tube-like structure called style which connects stigma to the ovary.

The swollen bottom part at the base of pistil is called ovary.
The ovary makes ovules and stores them. These ovules contain the female sex cells also called as egg cell. It is the female gamete of flower. Pistil is also called as carpel. The pistil is surrounded by several stamens.
The base of the flower on which all the parts of flower are attached is called receptacle.

Question 19.
Observe the given figure?

(a) Which plant is this? Give the name of the plant.
(b) What does it shows?
(c) From where the new plants are developing?
Answer:
(a) The given figure is of Bryophyllum leaf. It is also called as sprout leaf plant.
(b) It shows vegetative reproduction by leaves.
(c) The leaves of Bryophyllum develops some buds in its margin or edges which grow into new plants, when buried in the soil.

Question 20.
The process of layering is commonly used in jasmine for reproduction. Explain how this process of layering is performed in jasmine. [HOTS]
Answer:
Layering is a method of vegetative reproduction in branches. In this method, a mature branch of parent plant is bent down and covered with soil.
The tip of the branch is kept above the ground. After few days the roots are developed from the branch buried under the soil and develops into a new plant. This method is done in the plants that have long and slender branches, e.g. jasmine.

Reproduction in Plants Class 7 Science Extra Questions Long Answer Type Questions

Question 1.
In the figure of a flower given below, label the parts whose functions are given below and give their names.
(a) The part which contains pollen grains.
(b) The part where the female gamete is formed.
(c) The female reproductive part, where pollen grains germinate.
(d) The colourful part of flower which attracts insects[NCERT Exemplar]

Answer:
The various parts of a flower whose functions are mentioned above are labelled as follows :

Question 2.
Observe the following figure and answer the following questions.
(a) Which type of vegetative propagation has been shown in this figure?
(b) Name two plants where this method of vegetative reproduction takes place.
(c) Is this a sexual or asexual mode of reproduction?
(d) Label the part (A) and (B) in the given figure.

Answer:
(a) The given figure shows grafting method (vegetative reproduction).
(b) Mango and rose are the two plants where this method of vegetative takes place.
(c) It is asexual method of reproduction.
(d) (A) Scion (B) Stock

Question 3.
Explain the process of reproduction in plants, involving the fusion of cells from male and female parts of a flower.
Answer:
When the reproduction in an organism includes two types of gametes, i.e male and female from two different parents, it is called sexual reproduction. The sexual reproduction takes place by the fusion of male and female gametes by the process called fertilisation to form zygote.

Sexual reproduction [fertilisation) in plants The different steps that take place during sexual reproduction in plants are

The pollens are deposited on stigma and begins to germinate.
Pollen tube containing male gametes reaches to the ovary of flower.
The tip of the pollen tubes gets dissolved and male gametes comes out of the pollen tube.
Inside the ovary male gametes fuse with the female gamete or egg present in the ovule.
The fusion of both the gametes will result into a fertilised egg cell which is also called as zygote.

Question 4.
Name some fruit bearing plants. Now make a table and describe the method of seed dispersal in these fruits as well as the part which helps in the seed dispersal.
Answer:
The method of seed dispersal in the fruits and the parts which help in the seed dispersal:
Name of fruits bearing plants Agents through which seeds are dispersd Parts or seeds which helps in dispersal

Name of fruits bearing plants	Agents through which seeds are dispersd	Parts or seeds which helps in dispersal
Drumstick	Air/wind	Winged seeds
Sunflower	Wind	Hairy seeds
Gokhru	Animal	Spines and Hooks
Coconut	Water	Fibrous coating
Lotus	Water	Thalamus float in water
Poppy	Explosion	Pericarp bursts
Grass	Wind	minute, light weighted seeds

Question 5.
Observe the given figure and answer the following questions.
(a) Name the plant?
(b) Which type of reproduction is seen in this plant?
(c) Is ginger a root or stem?
(d) Label the part of this plant?

Answer:
(a) The given figure is of ginger tuber.
(b) Asexual reproduction is seen in this plant.
(c) Ginger is a stem.
(d) Various parts of this plant can be shown as follows:

Question 6.
Ria went to a plant nursery with her mother. The gardner approached them and asked about their choice of plant. Ria’s mother wanted a flowering plant with fragrance. Gardner showed them a plant and told them that this variety has been prepared by a method of vegetative propagation of stems.
Ria grew curious and asked some questions to gardner.
(a) What is vegetative propagation?
(b) What are methods of producing new plants using stem?
(c) Name any two plants where this method of reproduction is used. Is this a asexual or sexual method?
(d) What values do you observe in Ria? [Value Based Question]
Answer:
(a) Vegetative propagation is the process of reproduction in which new plants are produced from different parts of old plants like stem, roots or leaves.
(b) Cutting and grafting method are two methods where stem is used for vegetative propagation.
(c) Mango and rose are two plants cultivated using vegetative propagation.
This is an asexual method of reproduction.
(d) Ria is curious, inquiring who wants to gain knowledge about process occurring around here.

Question 7.
Ravi was sitting in a garden with his family. His younger sister comes running with different types of flowers and starts to name their parts. She stops as she forgets some names and Ravi noticing this comes to help her.
His sister askes many questions related to flowers and Ravi answers her with all information he has.
(a) What is a flower and mention its function during reproduction?
(b) Flowers help in pollination and fertilisation. Yes/No? Give reason.
(c) Do all flowers have both male and female parts on them specify?
(d) What values are observed in Ravi and his sister? (Value Based Question]
Answer:
(a) A flower is the reproductive part of plant which helps in sexual reproduction.
A flower ensures the occurrence of process of fertilisation.
(b) Yes, flower aids in both pollination and fertilisation. Different colours and fragrance of flowers attract insects to them causing dispersal of pollen grain ensuring pollination.
Fertilisation occurs in the ovary of the flower after pollination of male and female parts.
(c) Number of some flowers can either have male or female parts on them, these flowers are called unisexual.
Some flowers have both, the male and female parts on them so they are called bisexual flowers.
(d) Ravi is aware, sincere, helpful as he helps others and knowledgeable while his sister is inquisitive, ready to acquire new knowledge and observant.

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CHAPTER – 11 Transportation in Animals and Plants | CLASS 7TH | NCERT SCIENCE IMPORTANT QUESTIONS & MCQS | EDUGROWN

SCIENCE IMPORTANT QUESTIONS & MCQS FOR CLASS 7th

Chapter - 11 Transportation in Animals and Plants

MCQs

Question 1.
Which of the following is the main circulatory fluid in our body ?
(a) Plasma
(b) Lymph
(c) Blood
(d) None of these

Answer

Answer: (c) Blood

Question 2.
Which one of the following contains haemoglobin?
(a) RBC
(b) WBC
(c) Platelets
(d) None of these

Answer

Answer: (a) RBC

Question 3.
What is the function of WBCs?
(a) Transport of oxygen
(b) Fight against germs
(c) Involved in blood clotting
(d) All of these

Answer

Answer: (b) Fight against germs

Question 4.
Blood platelets help in
(a) formation of urine
(b) excretion of urine
(c) sweating
(d) blood clotting

Answer

Answer: (d) blood clotting

Question 5.
The muscular tube through which stored urine is passed out of the body is called:
(a) kidney
(b) ureter
(c) urethra
(d) urinary bladder

Answer

Answer: (c) urethra

Question 6.
They are pipe-like, consisting of a group of specialised cells. They transport substances and form a two-way traffic in plants. Which of the following terms qualify for the features mentioned above?
(a) Xylem tissue
(b) Vascular tissue
(c) Root hairs
(d) Phloem tissue

Answer

Answer: (d) Phloem tissue

Question 7.
The absorption of nutrients and exchange of respiratory gases between blood and tissues takes place in:
(a) veins
(b) arteries
(c) heart
(d) capillaries

Answer

Answer: (d) capillaries

Question 8.
In which of the following parts of human body are sweat glands absent?
(a) Scalp
(b) Armpits
(c) Lips
(d) Palms

Answer

Answer: (c) Lips

Question 9.
In a tall tree, which force is responsible for pulling water and minerals from the soil?
(a) Gravitational force
(b) Transportation force
(c) Suction force
(d) Conduction force

Answer

Answer: (c) Suction force

Question 10.
Aquatic animals like fish excrete their wastes in gaseous form as
(a) Oxygen
(b) Hydrogen
(c) Ammonia
(d) Nitrogen

Answer

Answer: (c) Ammonia

Match the following:

Column A	Column B
(i) Ammonia	(a) Food
(ii) Urea	(b) Carbon dioxide rich blood
(iii) Uric acid	(c) Water and salts
(iv) Vein	(d) Carry oxygen
(v) Artery	(e) Aquatic animals like fish
(vi) Xylem	(f) Fight against germs
(vii) Phloem	(g) Blood clotting
(viii) Sweat	(h) Absorb water
(ix) Root hair	(i) Humans
(x) Platelets	(j) Oxygen rich blood
(xi) RBCs	(k) Water and minerals
(xii) WBCs	(l) Birds, snakes, lizards

Answer

Answer:

Column A	Column B
(i) Ammonia	(e) Aquatic animals like fish
(ii) Urea	(i) Humans
(iii) Uric acid	(l) Birds, snakes, lizards
(iv) Vein	(b) Carbon dioxide rich blood
(v) Artery	(j) Oxygen rich blood
(vi) Xylem	(k) Water and minerals
(vii) Phloem	(a) Food
(viii) Sweat	(c) Water and salts
(ix) Root hair	(h) Absorb water
(x) Platelets	(g) Blood clotting
(xi) RBCs	(d) Carry oxygen
(xii) WBCs	(f) Fight against germs

Fill in the blanks:

1. Blood is the fluid which flows in the ………………..

Answer

Answer: blood vessels

2. ……………….. binds with oxygen and transports it.

Answer

Answer: Haemoglobin

3. ……………….. fight against germs.

Answer

Answer: WBCs

4. The heart has ……………….. chambers.

Answer

Answer: four

5. A doctor uses the ……………….. to feel the heart beat.

Answer

Answer: stethoscope

6. ……………….. discovered the circulation of blood.

Answer

Answer: William Harvey

7. Filtering the blood periodically through an artificial kidney is called ………………..

Answer

Answer: dialysis

8. Plants absorb water and minerals by the ………………..

Answer

Choose the true and false statements from the following:

1. Blood carries carbon dioxide from the body parts to the lungs.

Answer

Answer: True

2. White blood cells are involved in the clotting of blood.

Answer

Answer: False

3. There are valves present in veins.

Answer

Answer: True

4. Heart acts as a pump for the transport of blood.

Answer

Answer: True

5. Arteries have thin walls while veins have thick walls.

Answer

Answer: False

6. Human heart has two chambers, an atrium and a ventricle.

Answer

Answer: False

7. Partition between the chambers of heart avoid mixing up of blood rich in oxygen with the blood rich in carbon dioxide.

Answer

Answer: True

8. Stethoscope is a device to amplify the sound of the heart.

Answer

Answer: True

9. Rhythmic beating of the various chambers of the heart maintain circulation of blood to the different parts of the body.

Answer

Answer: True

10. When blood reaches the two kidneys, it contains only harmful substances.

Answer

Answer: False

Question 1 .
Name some useful products or materials that are carried by blood.
Answer:
Food, water and oxygen are the products that are carried by blood to every part of the body.

Question 2.
Circulatory system consists of three major organs. Name those organs.
Answer:
The circulatory system consists of three major organs, i.e., blood, blood vessels and heart.

Question 3.
Give the name of blood component which is liquid and contains 90% water.
Answer:
The sticky liquid part of the blood, containing 90% water is called plasma.

Question 4.
Name the organ which is located in the chest cavity with its lower tip slightly tilted towards the left. [NCERT Exemplar; HOTS]
Answer:
The heart is located in the chest cavity with its lower tip slightly tilted towards the left.

Question 5.
RBC contains a red coloured pigment which carries oxygen with it. What is the pigment called?
Answer:
The red coloured pigment of RBC that carries oxygen with it is called haemoglobin.

Question 6.
Veins have valves which allow blood to flow only in one direction. Arteries do not have valves. Yet the blood flows in one direction only. Can you explain why? [NCEAT Examplar; HOTS]
Answer:
Veins have valves to prevent blood from flowing backwards and pooling, whereas arteries pump blood at very high pressures, which naturally prevents back flow

Question 7.
In which form, the oxygen is transported to various body parts by haemoglobin?
Answer:
The red pigment, haemoglobin binds with oxygen to form oxyhaemoglobin which is transported to various body parts.

Question 8.
Certain greenish-blue lines appear just below the skin of our hands and leg. What are these?
Answer:
The greenish-blue lines that appear just below the skin of our hands and legs are veins.

Question 9.
Human blood group is divided into how many groups? Name them.
Answer:
Human blood group is divided into four groups. These are A, B, AB and O.

Question 10.
Waste carbon dioxide and urea are removed from our body by which organs?
Answer:
The carbon dioxide is removed by lungs while urea is removed from the body by kidney.

Question 11.
Blood is a fluid connective tissue. Justify.
Answer:
Blood is a fluid tissue which connects all the parts of body with each other.

Question 12.
Blood performs various functions including protection against infections. How?
Answer:
Blood contains WBC which forms the defense of our body. They eat antigens and fights aganist infections.

Question 13.
Pulse rate can indicate the health states of an individual. How?
Answer:
Pulse rate will increase or decrease from normal rate if a person is not well.

Question 14.
Usually veins carry deoxygenated blood except in one case. Specify.
Answer:
Pulmonary veins carry oxygenated blood from lungs to heart.

Question 15.
State the function of valves ?
Answer:
Valves prevent the back flow of blood between chambers of heart.

Question 16.
Name the functional units of the major excretory organ of humans.
Answer:
Kidney is the major excretory organ and nephrons are its functional units.

Question 17.
Exchange of gases, food and other substances occurs between arteries and veins. How does this exchange happen?
Answer:
Exchange of substances between arteries and veins occurs via capillaries.

Question 18.
Measuring of heartbeats is a significant step during health checkups. Name the instrument used for the same.
Answer:
Stethoscope

Question 19.
Kidneys are the major excretory organs in humans. How will the waste products released will be excreted out if the kidneys are damaged or unfunctional? [HOTS]
Answer:
Artificial ways of waste removal are used like dialysis which are referred to as artificial kidneys.

Question 20.
Arteries have a very thick and elastic walls. Why?
Answer:
Arteries carry blood at a very high pressure due to pumping action of heart hence, the need of thicker walls.

Question 21.
Skin is also considered as an excretory organ. Give reason if you agree. [HOTS]
Answer:
Yes, skin is an excretory organ as it secretes waste products by releasing sweat from the surface.

Question 22.
Heart has three chambers, two ventricles and one atrium. Is it right or wrong?
Answer:
Wrong, the heart has four chambers. Two auricles and two ventricles.

Question 23.
Arteries and veins carry blood to and from the heart. Which of these carry the blood?
(a) Back to the heart from all organs.
(b) Away from heart for distribution in all organs.
Answer:
(a) Veins
(b) Arteries

Question 24.
Urine is called an excretory product. Why?
Answer:
Urine is the mixture of urea and other unwanted salts with water which is needed to be excreted out as its presence in blood can make a person ill.

Question 25.
Sponges and Hydra do not possess any circulatory system then how do they carry out distribution of food and other substances?
Answer:
The water in which these organisms live brings them food and oxygen as it enters their bodies.

Question 26.
If the heartbeats of a person are more than 72-80 beats per minute. What does it signify?
Answer:
The faster heartbeats signify that heart is pumping more blood to the organs as they need increased oxygen and energy supply.

Question 27.
What is the purpose of using stethoscope by doctors?
Answer:
A stethoscope reads heartbeats as diaphragm amplies the rounds of heartbeat when placed on specific areas.

Question 28.
Urinary bladder is the part of human excretory system. What is its role in excretion?
Answer:
Bladder stores the excretory product released after filtration from kidney and excrete it out at specific times.

Transportation in Animals and Plants Class 7 Science Extra Questions Short Answer Type Questions

Question 1.
Arrange the following statements in the correct order in which they occur during the formation and removal of urine in human beings.
(a) Ureters carry urine to the urinary bladder.
(b) Wastes dissolved in water is filtered out as urine in the kidneys.
(c) Urine stored in urinary bladder is passed out through the urinary opening at the end of the urethra.
(d) Blood containing useful and harmful substances reaches the kidneys for filtration.
(e) Useful substances are absorbed back into the blood.
Answer:
The correct order of the formation and removal of urine in human beings is
(d) Blood containing useful and harmful substances reaches the kidneys for filtration.
(e) Useful substances are absorbed back into the blood.
(b) Wastes dissolved in water is filtered out as urine in the kidneys.
(a) Ureters carry urine to the urinary bladder.
(c) Urine stored in urinary bladder is passed out through the urinary opening at the end of the urethra.

Question 2.
Name the tissues of a plant which carries
(a) water and minerals from roots to the leaves.
(b) food from the leaves to the other parts of the plant.
Answer:
The tissue which carries
(a) water and minerals from roots to leaves is xylem.
(b) food from the leaves to the other parts of the plant is phloem.

Question 3.
Look at figure and draw another figure of the same set up as would be observed after a few hours.

Answer:
After the few hours, the figure will be shown as follows

This figure shows that there will be an increase in the level of sugar solution in the potato piece. This increase in the level of sugar solution rises due to water that passes throGgh the wall of potato and goes inside it.

Question 4.
(a) Name the only artery that carries carbon
dioxide rich blood.
(b) Why is it called an artery if it does not carry oxygen-rich blood? [NCERT Exemplar]
Answer:
(a) The only artery that carries carbon dioxide rich blood is pulmonary artery.
(b) The main function of artery is to carry blood away from heart. Also arteries have thick wall and do not contain valves in them. Blood flow in arteries, takes place at high pressure. All these characteristics are found in pulmonary artery. It carries deoxygenated blood from heart to lungs for oxygenation, therefore it is called artery.

Question 5.
Name the process and the organ which help in removing the following wastes from the body.
(a) Carbon dioxide
(b) Undigested food
(c) Urine
(d) Sweat [NCERT Exemplar]
Answer:

	Waste	Process	Organ
(a)	Carbon dioxide	Exhalation	Lungs
(b)	Undigested food	Egestion	Large intestine and anus
(c)	Urine	Excretion	Kidneys
(d)	Sweat	Perspiration (sweating)	Sweat glands

Question 6.
Observe given figure and answer the given question.

(a) Name the instrument.
(b) Label the parts A, B and C. [NCERT Exemplar]
Answer:
(a) The name of the given instrument is stethoscope.
(b) Labelled diagram of stethoscope.

Question 7.
What is the relation between the rate of heartbeat and pulse rate? If a pulse rate of an athlete Is 96/min, what will be the number of his heartbeat at the same time? [HOTS]
Answer:
The rhythmic contraction and relaxation of the muscles of the heart is called heartbeat. Whereas, the rhythmical throbbing of the arteries as the blood is pushed forward through them is called pulse. It can be felt in the wrist, temples, etc.
Pulse rate is the number of heartbeats per minutes. The number of heartbeat is equal to the number of pulse per minute.
Therefore, if a pulse rate of an athlete is 96/min then the number of his heartbeat at the same time will also be 96/min

Question 8.
Give one function of each of the following organs,
(a) Blood vessels
(b) Kidney
(c) Blood platelets
(d) Heart
Answer:
The main function of the following organs are as follows:
(a) Blood vessels These run between the heart and the rest of the body. It helps in the transport of blood between heart and various organs of the body.
(b) Kidney It is called as the ‘magic filters’. It helps in the removal of unwanted substances like urea from the blood.
(c) Blood platelets This component of blood helps in blood clotting and prevents the blood loss from the body.
(d) Heart It is a pumping organ which receives blood from the body through veins and pumps it with enough force into the arteries from where it is carried to the various body parts.

Question 9.
Paheli noticed water being pulled up by a motor pump to an overhead tank of a five storeyed building. She wondered how water moves up to great heights in the tall trees standing next to the building. Can you tell why? [NCERT Exemplar; HOTS]
Answer:
When the water is pulled up by a motor-pump to an overhead tank of a five storeyed building, it moves to a great height due to the suction pull. This pull forms the continuous column of water and water rises up to a great height. Similarly, when transpiration occurs in the plants, water is evaporated and this creates a suction pull in the plants.

Due to this suction pressure, water from the soil rises up through the roots of the plants and reaches to a great height in tall plants.

Question 10.
How is transpiration and translocation different from each other.
Answer:
The differences between transpiration and translocation are

Transpiration	Translocation
The evaporation of water from the leaves of plant is called transpiration.	The transport of soluble products of photosynthesis from leaves (from where they are formed) to the other parts, of plants is called translocation.
It takes place through stomata present in the lower surface of leaf.	It occurs in the part of the vascular tissue known as phloem.

Question 11.
Make a table depicting the function of all chambers of the human heart.
Answer:
The human heart is divided into four chambers, i. e. upper two atrium and lower two ventricles. The functions of these chambers can be tabulated as follows

Chamber	Function
Left atrium	Receives oxygenated blood from lungs through pulmonary veins and pours it into left ventricle.
Right atrium	Receives deoxygenated blood from various body parts through superior and inferior vena cava and pours it into right ventricle.
Left ventricle	Pumps oxygenated blood to various parts of body through aorta.
Right ventricle	Pumps deoxygenated blood into lungs through pulmonary artery.

Question 12.
How does the water move from root to leaves?
Answer:
The water moves from root to leaves with the help of specialised cells called vascular tissue. Transport of water and nutrients is done by xylem tissue present in plants.

Question 13.
Observe the given diagram of human heart and label all the parts from A to H.

Answer:

The heart is an organ which beats continuously as a pump for the transport of blood carrying other substances with it, through a network of tubes or blood vessels. The heart pumps blood throughout our life without stopping or relaxing.

Question 14.
The given diagram is of human excretory system. Label the marked parts of it.

Answer:
The various parts of human excretory system are as follows

Question 15.
Paheli says her mother puts ladyfinger and other vegetables in water if they are somewhat dry. She wants to know how water enters into them. [HOTS]
Answer:
By soaking the vegetables in water, the skin of the vegetables becomes moist and water starts moving from one cell to another until the vegetables are fresh again.

Question 16.
Why plants absorb a large quantity of water from the soil, then give it off by transpiration?
Answer:
Plants absorb a large quantity of water from the soil because they need nutrients which are dissolved in the water. The excess water evaporates through the stomata present on the leaf surface by the process of transpiration.

Question 17.
List some animals surrounding your locality group them into following groups.
(a) Animals that excrete ammonia in gaseous forms.
(b) Animals that excrete uric acid in the form of pellets.
(c) Animals that excrete urea in the form urine. [HOTS]
Answer:
Some animals that surround us are fish, frog, birds, tadpole larva, snake, cow, man, rat, monkey, lizard, toad and snail.
These can be grouped as follows
(a) Animals that excrete ammonia in gaseous form (i.e. ammonotelics)-Fish, tadpole larva.
(b) Animals that excrete uric acid in the form of pellets (i.e. uricotelics)—Bird, snake, rat, lizard, snail.
(c) Animals that excrete urea in the form of urine (i.e. ureotelics)-Frog, cow, man, monkey, toad.

Question 18.
Human have two major organs that perform transport of materials. Organ ‘A’ is bean-shaped and dark red in colour lie just above the waist. It helps in’removal of ‘Q’, a waste material from blood. The organ ‘S’ is the opening at the end of the urinary bladder through which the waste material is eliminated.
Organ ‘B’ lies in the chest cavity slightly tilted towards the left side. It pumps continuously and pours liquid ‘C’ into arteries and through very fine tube-like structure ‘D’ distributes the liquid to various parts of the body. What are the name of these organs. [HOTS]
Answer:
Organ ‘A’ is kidney which is bean-shaped and helps in the removal of urea (Q) which is a waste material from the blood. ‘S’ is urethra which is the small opening at the end of urinary bladder. Organ ‘B’ is heart which acts as pump. It pumps liquid blood continuously and pours into arteries, and through capillaries (D) which are fine tube-like structure, the blood is distributed to various parts of the body.

Question 19.
The major function of the arteries is to carry to oxygenated blood throughout the body and that of veins is to carry deoxygenated blood from body parts to heart for purification. There is one artery that carries deoxygenated blood and one vein that carries oxygenated blood. Name the artery and vein. [HOTS]
Answer:
The artery which carries deoxygenated blood or blood rich in CO₂ is pulmonary artery while the pulmonary vein is one which carries oxygenated blood. The pulmonary artery carries deoxygenated blood from heart to lungs while pulmonary vein carries oxygenated blood from lungs to heart.

Question 20.
Boojho’s uncle was hospitalised and put on dialysis after a severe infection in both of his kidneys.
(a) What is dialysis?
(b) When does it become necessary to take such a treatment?
Answer:
The normal functioning of kidney is necessary for good health of a person. But sometime s the kidney may stop working due to infection or injury. This condition of kidney is called kidney failure which may lead to the accumulation of urea in the blood of a person. Since, urea is a toxic substance which must be removed from the blood. Such person having kidney failure cannot survive unless his blood is filtered periodically through the artificial kidney machine to remove urea. The process used for cleaning the blood of a person by separating the waste product urea from it is called dialysis.This machine removes urea and other waste the product periodically.

The long term solution for the patient suffering from kidney failure is kidney transplantation. In this method, the diseased or damaged kidney is removed and matching kidney is donated by a healthy person. The donated kidney is transplanted in its place by performing surgery.

Question 21.
The internal structure of heart has four chambers.
(a) Name the upper chambers of heart.
(b) Name the lower chambers of heart.
Answer:
The vertical section of heart shows that heart is divided into four compartments called as chambers.
(a) The upper two chambers of heart are called atria or atrium.
(b) The lower two chambers of heart are called ventricles.

Question 22.
Explain in brief the main functions of the structural and functional unit of kidney in excretory system.
Answer:
Kidney is the major excretory organ which consists of thousands of tiny filters called nephrons. The major functions of nephron are

To filter blood at high pressure which helps in the separation of nitrogenous waste such as urea from the blood.
It helps in selective re-absorption of some substances (from the initial filtrate which is filtered at a very high pressure). These substances include glucose, amino acid, salts ancf a major amount of water.

Question 23.
What is the special feature present in a human heart which does not allow mixing of blood when oxygen-rich and carbon dioxide-rich blood reach the heart? [NCERT Exemplar]
Answer:
In human, the heart has four chambers. The two upper chambers are called the atria and the two lower chambers are called the ventricles. The partition between the chambers helps to avoid mixing up of blood rich in oxygen with the blood rich in carbon dioxide.

Question 24.
Paheli uprooted a rose plant from the soil. Most of the root tips with root hairs got left behind in the soil. She planted it in a pot with new soil and watered it regularly. Will the plant grow or die? Give reason for your answer. [NCERT Exemplar, HOTS]
Answer:
Possible answers are

Without the root hairs, the roots will not be able to absorb water and nutrients and the plant will die.
The stem of the rose plant may grow new roots and the plant will live.
The rose plant may not be able to survive in a different type of soils.

Transportation in Animals and Plants Class 7 Science Extra Questions Long Answer Type Questions

Question 1.
Priya’s grandfather was taken to the hospital as he was unable to perform excretory processes. Priya heard a nurse talking to her father that her grandfather’s has kidney failure and needs to undergo dialysis. Priya later asked her father as to what is dialysis process and why does grandpa needs it. Her father smiles and tells her all the facts associated with this process.
(a) What do you mean by dialysis?
(b) Why is there a need for dialysis in some people?
(c) Excretion is an important life process. How?
(d) Which is the major excretory organ in humans?
(e) What values do you observe in Priya? [Value Based Question]
Answer:
(a) Dialysis is the process used for cleaning of the blood by separating the waste products in an artificial medium.
(b) Dialysis is needed when the excretory organ of humans, i.e. kidney becomes damaged on unfunctional due to some injury or infection.
(c) Excretion process removes the waste products released in body after the utilisation of food and other components. These products are toxic and may harm us if not removed from our body.
(d) Kidney
(e) Priya is curious, sincere and aware eager to acquire new knowledge.

Question 2.
While learning to ride a bicycle, Boojho lost his balance and fell. He got bruises on his knees and it started bleeding. However, the bleeding stopped after sometime.
(a) Why did the bleeding stop?
(b) What would be the colour of the wounded area and why?
(c) Which type of blood cells are responsible for clotting of blood? [NCERT Exemplar]
Answer:
(a) When a cut or wound starts bleeding after sometime, a clot is formed which plugs the cut and bleeding stops.
(b) Wounded area becomes dark red in colour due to clotting of blood.
(c) The blood clot is formed due to the presence of the cells called platelets in the blood.

Question 3.
Like humans and animals, transportation of water, mineral and nutrients also take place in plants. How?
Answer:
Transport of Substances in Plants
Plants take up water and dissolved minerals from the soil through their roots and transport it to their leaves. The leaves use this water and mineral for synthesising their food by the process called photosynthesis.The food produced by green plants in transported back to all the parts of plant body.
Therefore, it is clear that plants also need a transport system for carrying water, minerals and food through various parts of their body.

Transport of Water and Minerals
Plant root absorbs the water and mineral from the soil. The roots possess root hair which increase the surface area of the root for absorption of water and minerals nutrient that is dissolved in the water. It is moved from roots up to the stem and leaves through the tube-like tissue called as xylem.

Absorption and flow of water is a continuous process through the xylem tissue. Xylem tissues are the continuous network of channels which connect roots to the leaves through the stem and branches. It thus transports water and minerals to the leaves of the entire plant.

Transport of Food Material
The food manufactured in the leaf is transported to different parts of plants. This transportation of food material from leaves to the other parts of plants is carried out by the tissue called phloem and the process of transport of food material is called translocation. The phloem consists of vessels that are known as sieve tubes.

Question 4.
Blood from heart is carried by certain tube-like structure. What are they? Give the structure and functions of different types of blood carrying tubes.
Answer:
These are tubes or pipes that carry blood throughout the body. It runs between the heart and the rest of the body. There are three major types of blood vessels in the body, i.e. arteries, veins and capillaries.

1. Arteries: These carry blood from the heart to all the parts of body. These lie quite deep under our skin and cannot be seen easily. Arteries have thick elastic walls as the blood flows at high pressure due to pumping action from heart through arteries. No valves are present in the arteries. The main artery, i.e. aorta is connected to the left ventricle of the heart. It carries oxygenated blood from the left ventricle to all the parts of body except the lungs. Another artery called pulmonary artery is connected to the right ventricle of the heart and carries deoxygenated blood from the right ventricle to the lungs.
Note: The arteries normally carry oxygenated blood from the heart but one artery called pulmonary artery carries deoxygenated blood from heart to lungs.

2. Veins: These are the blood vessels that carry blood from all the parts of the body back to the heart. These tube-like blood vessels are situated just under the skin and can easily be seen as greenish-blue tubes or lines below the skin. These carry deoxygenated blood from the body parts to heart. Veins have thin walls and blood flows at low pressure through the veins. Therefore, veins have valves in them which allow the blood to flow in one direction and prevent the back flow of blood in veins.
Usually veins carry deoxygenated blood but pulmonary vein that is connected to the left atrium of the heart, carries oxygenated blood from the lungs to the heart.

Functions of Blood
Various functions of blood are

It transports substances like digested food from the small intestine to the other parts of the body.
It carries water to all the parts of the body.
It carries oxygen and C02 during circulation.
It carries waste products like urea from liver to kidney for excretion in urine.
It protects the body from disease.

Question 5.
While riding a bike, Mason fell from it due to loss of balance. He got up and realised that he was bleeding from several wounds badly. He panicked and started to run but Mansi who was looking at him, stopped him and told him to clean his wound with a clean cloth and that blood will stop coming in a while. Mason noticed that he has stopped bleeding after sometime and a hard covering was appearing on his wounds.
(a) Why did the bleeding stop after a while?
(b) What is blood and what type of cells are responsible for clotting?
(c) What of values do you think Mansi have? [Value Based Question]
Answer:
(a) Bleeding stops after sometime because some specialised cells start forming a hard covering called clot at the site of wound.
(b) Bleeding is a fluid connective tissue present in all parts of the body. Platelets are responsible for formation of clot.
(c) Mansi is helpful, knowledgeable and interested in science subject.

Question 6.
Read the following terms given below,
root hairs xylem urethra
arteries kidneys veins
atria capillaries heart
ureter phloem urinary bladder
Group the terms on the basis of the categories given below.
(a) Circulatory system of animals.
(b) Excretory system in human.
(c) Transport of substances in plants. {NCERT Exemplar]
Answer:
The terms on the basis of the categories can be grouped as follows
(a) Circulatory system of human Arteries, atria, capillaries, veins, heart.
(b) Excretory system in human
Urethra, kidneys, ureter, urinary bladder.
(c) Transport of substances in plants Root

Question 7.
(a) What are the different blood groups in human?
(b) Define blood group compatibility.
(c) Make a table to show the donor blood group and recipient blood group.
Answer:
(a) The blood group of an individual human being always remains unchanged throughout their life. Karl Landsteiner described that human blood can be divided into four groups, i.e. A, B, AB and O. These are named on the basis of substance present in the blood (RBC). Every man has one of these four groups of blood which is inherited from parents to offspring and is never changed.

If a person gets injured and heavy blood loss occurs, there is a need to give blood of other person to the patient. The person who gives the blood is called donor while the person who receives the blood is called
recipient.

(b) The process of donation of blood from one person to another is called blood transfusion. Before donation, the blood group must be matched because transfusion of different groups can be dangerous. The RBCs of the patient receiving blood will stick together and may cause death of the patient. This matching of blood group is called blood group compatibility. It can be shown as follows :

(c)

Blood group	Can donate blood to	Can receive blood from
A	A and AB	A and O
B	B and AB	B and O
AB	AB	All the group, i.e. A, B, AB and O
O	All the group, i.e. A, B, AB and 0	O

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CHAPTER – 10 Respiration in Organisms | CLASS 7TH | NCERT SCIENCE IMPORTANT QUESTIONS & MCQS | EDUGROWN

SCIENCE IMPORTANT QUESTIONS & MCQS FOR CLASS 7th

Chapter - 10 Respiration in Organisms

MCQs

Question 1.
Sometimes when we do heavy exercise, anaerobic respiration takes place in our muscle cells. What is produced during this process?
(a) alcohol and lactic acid
(b) alcohol and CO₂
(c) lactic acid and CO₂
(d) lactic acid only

Answer

Answer: (d) lactic acid only

Question 2.
Yeast is used in wine and beer industries because it respires.
(a) aerobically producing oxygen
(b) aerobically producing alcohol
(c) anaerobically producing alcohol
(d) anaerobically producing CO₂

Answer

Answer: (c) anaerobically producing alcohol

Question 3.
During the process of exhalation, the ribs move
(a) down and inwards
(b) up and inwards
(c) down and outwards
(d) up and outward

Answer

Answer: (a) down and inwards

Question 4.
Breathing is a process that
(i) provides O₂ to the body.
(ii) breaks down food to release energy.
(iii) helps the body to get rid of CO₂
(iv) produces water in the cells.
Which of the following gives the correct combination of functions of breathing?
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (i) and (iii)
(d) (ii) and (iv)

Answer

Answer: (c) (i) and (iii)

Question 5.
Which are the gases involved in breathing?
(a) O₂ and NO₂
(b) O₂ and SO₂
(c) O₂ and O₃
(d) O₂ and CO₂

Answer

Answer: (d) O₂ and CO₂

Question 6.
Name the organ of the body in which the blood is oxygenated.
(a) Heart
(b) Lungs
(c) Lever
(d) Pancreas

Answer

Answer: (b) Lungs

Question 7.
After heavy exercise, due to the accumulation of which substance we get muscle cramps ?
(a) Malaic acid
(b) Fumaric acid
(c) Lipoic acid
(d) Lactic acid

Answer

Answer: (d) Lactic acid

Question 8.
Yeasts are used in
(a) wine and beer industry
(b) bakery
(c) in both
(d) none of these

Answer

Question 9.
In the following figure of respiratory system organs labelled by 1 and 2 are respectively:

(a) Tracheae, Lungs
(b) Lungs, Tracheae
(c) Nasal cavity, Lungs
(d) Lungs, Nasal cavity

Answer

Answer: (a) Tracheae, Lungs

Question 10.
Breathing rate in human beings in normal condition is
(a) 12-15 times in a minute
(b) 15-18 times in a minute
(c) 18-22 times in a minute
(d) 22-25 times in a minute

Answer

Answer: (b) 15-18 times in a minute

Match the following:

Column A	Column B
(i) Unicellular organisms	(a) Skin
(ii) Plants	(b) Spiracles
(iii) Earthworm, Leech	(c) Cell membrane
(iv) Insects	(d) Lungs, skin
(v) Frog	(e) Stomata
(vi) Mammals	(f) Gills
(vii) Fish	(g) Lungs

Answer

Answer:

Column A	Column B
(i) Unicellular organisms	(c) Cell membrane
(ii) Plants	(e) Stomata
(iii) Earthworm, Leech	(a) Skin
(iv) Insects	(b) Spiracles
(v) Frog	(d) Lungs, skin
(vi) Mammals	(g) Lungs
(vii) Fish	(f) Gills

Fill in the blanks

1. In higher animals, respiration occurs through ……………….

Answer

Answer: lungs

2. The food has ………………. which is released during ……………….

Answer

Answer: stored energy, respiration

3. Yeasts can survive in the absence of air. They are called ……………….

Answer

Answer: anaerobes

4. The accumulation of ………………. causes muscle cramps.

Answer

Answer: lactic acid

5. The taking in of air rich in oxygen into body is called ……………….

Answer

Answer: inhalation

6. Breathing involves the movement of the ………………. and the ……………….

Answer

Answer: diaphragm, rib-cage

Choose the true and false statements from the following:

1. All living organisms respire to get energy from food.

Answer

Answer: True

2. Cellular respiration takes place in the cells of all organisms.

Answer

Answer: True

3. Muscles can also respire anaerobically.

Answer

Answer: True

4. During heavy exercise the breathing rate declines.

Answer

Answer: False

5. Breathing involves the upward movement of the diaphragm.

Answer

Answer: False

6. The percentage of carbon dioxide is higher in exhaled air in comparison to inhaled air.

Answer

Answer: True

7. Roots take up air from the air spaces present between the soil particles.

Answer

Answer: True

Question 1.
What are the end products of aerobic respiration.
Answer:
During aerobic respiration, carbon dioxide and water are released along with a large amount of energy.

Question 2.
The cellular respiration process takes place in which cell organelle?
Answer:
Cellular respiration takes place in the mitochondria of the cell.

Question 3.
Name the end products of anaerobic respiration in yeast.
Answer:
The end product formed during anaerobic respiration in yeast are

Ethyl alcohol
Carbon dioxide
Energy

Question 4.
In some animals, exchange of gases takes place through its thin and moist skin. Name one such animal. [HOTS]
Answer:
Earthworm is an animal where exchange of gases during breathing or respiration takes place through its thin and moist skin.

Question 5.
Give the name of respiratory organs in following animals.
(a) Fish
(b) Human being
Answer:
The respiratory organ of the following animals are as follows
(a) Fish – Gills
(b) Human being – lungs

Question 6.
Our nostrils has hair and mucous. What is the need to have them in our nasal cavity? [HOTS]
Answer:
Our nostrils possess hairs and mucous lining. These help in preventing dirt, dust and germs from entering our respiratory system.

Question 7.
Sometimes we see that farmers loosen the soil. What is the reason behind it?
Answer:
The farmers sometimes loosen the soil. This helps the root to respire through the air present in the space between soil particles.

Question 8.
Various organs constitute the respiratory system of human. These organs are located according to their functions. Identify them.
Answer:
The various organs in the respiratory system of human are nostrils, nasal passage, nasal cavity, windpipe and lungs.

Question 9.
The vocal ability of humans is the responsibility of an organ commonly known as voice box. What is its scientific name?
Answer:
The organ that is responsible for speech is larynx or voice box. It lies between pharynx and trachea.

Question 10.
What changes are observed in diaphragm during inhalation?
Answer:
During the process of inhalation diaphragm contracts and moves downwards.

Question 11.
When we exhale or breathe out, percentage of a certain gas is high. Name the gas.
Answer:
The gas, carbon dioxide is in higher percentage or amount, when we exhale or breathe out.

Question 12.
In the experiment, where we exhale into lime water containing glass. What changes were observed by you?
Answer:
When we exhale into lime water its colour changes, into slightly milky white because exhaled air contains CO₂.

Question 13.
Insects have a special organ present to carry out respiration. What is that organ called?
Answer:
Insects possess special organ called spiracles for respiration.

Question 14.
Name the respiratory organs in frogs.
Answer:
Frogs respire through their moist skin as well as through a pair of lungs.

Question 15.
Certain small pores are present on the surface of plant through which gaseous exchange occurs. Identify these pores?
Answer:
Stomata are the tiny pores that are present on the surface of plant through which gaseous exchange occurs.

Question 16.
What happens to your breathing rate when you
(a) exercise
(b) go to sleep
Answer:
The breathing rate during exercise is increased while during sleep it goes down.

Question 17.
Floor of chest cavity refers to which organ of respiration?
Answer:
Diaphragm is known as the floor of chest cavity.

Question 18.
Respiration is a continous process. What is the need for it to be continuous rather than being like photosynthesis?
Answer:
Process of respiration yields energy which is required to perform a variety of routine activities. Thus, it needs to be a continuous process.

Question 19.
A part from stomata another structure is used by plants to respire. Name that structure.
Answer:
Lenticels.

Question 20.
Name the organisms which respire using anaerobic mode. Give an example of ane such organism.
Answer:
Anaerobes respire using anaerobic mode. Yeast is an organism respiring anaerobically.

Question 21.
Explain cellular respiration.
Answer:
The process of braeakdown of food in the cell with the release of energy is called cellular respiration.

Question 22.
All organisms breathe in O₂ and CO₂. Should be less O₂and excess of CO₂ in our environment. [HOTS]
Answer:
The CO₂ released by us is used by plants during the process of respiration and they release O₂ as a result of this process which is used by rest of the organisms.

Question 23.
The process of fermentation is based on which principle?
Answer:
Anaerobic respiration.

Question 24.
When oxygen enters our body it combines with haemoglobin to form a new substance. What is that new product.
Answer:
Oxyhaemoglobin.

Question 25.
Is the rate of breathing same for all the respiring organism?
Answer:
No, different organisms respire at different rate because they all perform different activities at all times.

Question 26.
Which gas present in air is essential for aerobic respiration? What is the role of this gas during respiration?
Answer:
Oxygen present in air is essential for aerobic respiration.
Oxygen breaks down food and releases energy during respiration.

Question 27.
On a very cold morning, Boojho and Paheli were talking with each other as they walked down to their school. They observed that the air coming out of their mouth looked like smoke. They were asumed and wondered how it happened. Help them to find the answer. [HOTSl
Answer:
On a cold day, the warm and moist air exhaled by us condenses into moist when it comes in contact with the cold air of the atmosphere, this looks like white smoke.

Respiration in Organisms Class 7 Science Extra Questions Short Answer Type Questions

Question 1.
Pick the odd one out from each of the groups given below on the basis of respiratory organs. Give reason for your answer.
(a) Cockroach, grasshopper, snail, ant
(b) Lizard, cow, earthworm, snake
(c) Crocodile, whale, dolphin, fish
(d) Snake, tadpole, crow, goat [NCERT Exemplar]
Answer:
(a) Snail, as it does not breathe by means of trachea.
(b) Earthworm, because it breathes through its skin and it does not have lungs.
(c) Fish, as most fish breathe through their gills and do not have lungs.
(d) Tadpole, as it breathes through gills and do not have lungs.

Question 2.
Insects and leaves of a plant have pores through which they exchange gases with the atmosphere. Can you write two points of differences between these pores with respect to their position, number and extension into the body?
Answer:
Pores present on the sides of insects are called spiracles while pores present on the surface of leaves are called stomata. These structures are responsible for the exchange of gases with the atmosphere.
Differences between these two are as follows

Spiracles are fewer in number as compared to stomata.
Spiracles lead to an extensive network of tracheal system which is absent in the leaves.

Question 3.
Frogs are amphibians. They survive on land and water, do they have any respiratory issue? How does frog breathe when they are in water? Do they possess lungs? Explain the role of lungs in frogs.
Answer:
Frog breathe by their moist skin and through lungs also. So, they do not have any, respiratory issue.
When frog enters into water, the skin of frog helps in respiration.
The oxygen rich air enters through the skin. When the frog is on land, a pair of lungs helps in respiration.
The lungs take the oxygen rich air through the nostrils from where the oxygen is absorbed by the blood and carried throughout the body. The carbon dioxide from the blood is diffused back through the skin and lungs into the atmosphere.

Question 4.
After we work hard or perform physical activity, we feel hungry. Explain why.
Answer:
When we work hard or perform physical activity (like running, swimming, cycling), we need mdre energy. To fulfil the energy requirement, we breathe faster. Fast breathing helps in supply of more oxygen to our cells. Due to this, rate of breakdown of food increases and more energy is released. The rapid breakdown of food makes us to feel more hungry.

Question 5.
Name one organism who respires anaerobically. How does this organism help in beverage and baking industry?
Answer:
Yeast is a single celled organism. During anaerobic respiration (also called fermentation), yeast produces ethanol or alcohol as a byproduct which is used in making wine and beer. The carbon dioxide produced by yeast is used in the bread making industry. The CO₂ gas released during this process causes the bread dough to rise.

Question 6.
Smoking is considerd harmful due to certain effects. Explain in brief. [HOTS]
Answer:
Lungs are very delicate organs and essential for breathing, thus beeping us alive. Smoking tobacco in the form of beedi, cigarette or cigar damages our lungs gradually and causes ill health. While smoking, smoke along with chemicals present in tobacco enters our body. These chemicals present in tobacco damages the lungs in many ways tike breathing becomes difficult causes lung cancer, heart diseases, etc. Smoking also affects people around smokers as they also inhale air containing tobacco. This is called passive smoking .
Refer to text on page 141.

Question 7.
Respiration can occur in two different manners. Briefly explain the process of aerobic respiration. How does it differ from anaerobic respiration?
Answer:
Types of Respiration
On the basis of the presence or absence of oxygen, respiration is classified into two types:
1. Aerobic Respiration: When breakdown of glucose occurs with the use of oxygen, it is called aerobic respiration. During aerobic respiration, glucose is completely broken down into carbon dioxide and water and energy is released. Aerobic respiration takes place in mitochondria. It can be shown by the following equation:

Aerobic respiration is seen in most of the organisms such as humans (man), dogs, cats, lions, elephants, cows, buffaloes, goats, snakes, earthworms, frogs, fishes, etc.

2. Anaerobic Respiration: When breakdown of glucose takes place without using oxygen, it is called anaerobic respiration. The glucose is not completely broken down into carbon dioxide and water. An intermediate compound is formed with the release of less amount of energy during this process. It can be shown as follows:

Yeasts such as Saccharomyces cereviseae and certain bacteria carry out anaerobic respiration. These organisms that carry out respiration in the absence of oxygen are called anaerobes.

Question 8.
Breathing rate of a person is not always constant. Give the reason for your answer.
Answer:
The number of times a person breathes in a minute is termed as breathing rate. An adult human being can inhale and exhale 15-18 times in a minute. It is the average breathing rate of an adult human being.

Breathing rate of a person is not always constant. It changes according to the oxygen requirement of the body. Breathing rate is somewhat faster in women than in men and in children it is higher (20-30 times/min) than adults. Breathing rate is slowest while sleeping (as less energy is required) while maximum during heavy exercise like running, weight lifting, etc. (much energy is required). Increased breathing rate provides greater amount of air entry into the lungs, hence blood can absorb oxygen at a faster rate. Faster breathing supplies more oxygen to the body cell for producing more energy, required for heavy exercises.

During heavy exercise the breathing rate can increase upto 25 times per minute. Because of this, food gets broken down at a faster rate and thus make us feel hungry.
When we feel drowsy, sleepy or tired, we yawn (i.e. open our mouth wide to take a long and deep breathe, of air), because our breathing rate slows down and body do not receives sufficient oxygen.

Question 9.
Whenever we feel drowsy or sleepy, we start yawning. Does yawning help us in anyway? [NCERT Exemplar; HOTS]
Answer:
When we feel drowsy, sleepy or tired, we yawn (i.e. open our mouth wide to take a long and deep breathe, of air), because our breathing rate slows down and body do not receives sufficient oxygen.

Question 10.
Respiration in fish is different from humans. Explain in brief how fishes can breathe through gills?
Answer:
Fishes are the aquatic animals that live in water. These have a special organ for breathing called gills. The oxygen dissolved in water enters through the gills. Gills are actually the projections of skin and have blood vessels for the exchange of respiratory gases. The fishes breathes by taking in water through its mouth and sending it over the gills. The oxygen dissolved in the water is extracted by the gills and the extracted oxygen is absorbed by the blood.

This oxygen is then carried to all the parts of fishes for respiration. The carbon dioxide produced during respiration is brought back by the blood into the gills and expelled into the surrounding water.

Question 11.
There are three animals named A, B and C. Among them A can stay on land as well as in water. When it stays at land is respire through lungs but when it goes into water, it respires through its moist skin. Animal B has specific organs to respire in the water which is not found in any other water animal. While animal C is a water animal which respires through nostrils and lungs. Now give the name of animal A, B and C. [HOTS]
Answer:
Animal A can live on land as well as in water and can respire through lungs as well as moist skin. The animal is frog.
Animal B lives in water and respires through a specific organ called gills. These are found in the tadpoles besides fishes. The animal B is a fish.
Animal C is also an aquatic animal which lives in sea water and respires through nostrils and lungs not by the gills. The animal is whale.

Question 12.
When breathe is released after holding it for few minutes. What happens and give reason for its occurrence?
Answer:
Releasing breathe after holding it for sometime results in rapid breathing. It occurs to maintain a healthy balance between intake of O₂ and release of carbon dioxide.

Question 13.
Observe the given figures carefully.and answer the following questions.
(a) The amount of CO₂ be the highest in which jar. Why?
(b) The amount of CO₂ be the lowest in which one and why?

Answer:
(a) The amount of CO₂ will be the highest in jar C. It is because the mice kept under the jar will breathe out CO2 continuously increasing its amount in the jar.
(b) The amount of CO₂ will be the lowest in jar A. It is because in jar A, CO₂ released during respiration is used by the plants, i.e. during the process of photosynthesis.

Question 14.
Whales and dolphins are seen many times releasing a fountain of water sometimes at the surface of water. Why do they do so?
Answer:
Sea animals like dolphins and whales live in water but unlike fishes, they do not possess gills for respiration. These possess nostrils which are called blow holes. There blow holes are located on the upper parts of their heads. These animals breathe in through their nostrils and lungs. Dolphins and whales comes to the surface of sea-water from time to time to breathe in air, sometimes whales release a function of water that moves upwards like a spray. This is because when a whale breathes air out of its blow hole it appears as a spray or misp, also called as spont. It can be seen from many miles away. Blow holes are surrounded by muscles that keep the holes closed when the whales or dolphins are under water and opens it when the animal is at the surface and needs to breathe.

Human cannot survive under water because they do not possess any gills to make use of oxygen dissolved in water for breathing. When we go under water we have to take oxygen gas cylinders for breathing.

Question 15.
Observe the given diagram of human respiratory system. List the organs from (A) to (G).

Answer:
The human respiratory system have following organs:
A-Ribs
B-Trachea
C-Pharynx
D-Diaphragm
E-Lungs
F-Nasal passage
G-Oral cavity

Question 16.
A girl was suffering from cold and was sneezing continuously. She joined her family at dinner and suddenly started sneezing without covering her nose, thus sending particles all over the place. On realising her mistake, said sorry and next time covered her nose.
(a) During sneezing, what are the precautionary steps to be followed?
(b) Can infections be passed from one person to another via sneezing?
(c) Is sneezing a respiration process?
(d) What values do we pick from this situation? (Value Based Question]
Answer:
(a) When sneezing, you should cover your nose so that the particles expelled by you would not be inhaled by others.
(b) Yes.
(c) No, it is process to remove/clear the particles harmful for us resulting in clean, fresh air to enter the lungs.
(d) Cleanliness and hygiene maintenance.

Respiration in Organisms Class 7 Science Extra Questions Long Answer Type Questions

Question 1.
A food stall owner was preparing dough for making bhaturas. He added a pinch of yeast and sugar to the dough and left it in a warm place. After few hours, the dough had risen. There was a sour smell too.
(a) Why did the dough rise?
(b) Why did the dough smell sour?
(c) Why was sugar added to the dough?
(d) What would have happened if the dough was kept in the refrigerator, soon after it was prepared?
Answer:
(a) The dough rises due to the release of carbon dioxide during anaerobic respiration by yeast cell.
(b) Yeast, during anaerobic respiration also produces alcohol which results in the sour smell of dough.
(c) Sugar is added into the dough, because it acts as a food for yeast. Yeast upon incomplete breakdown of sugar or food produces CO₂, alcohol and energy (in less amount).
(d) If the dough is kept in the refrigerators after it was prepared, then dough will neither raise nor become sour. Yeast requires high temperature to grow, multiply and to respire. At low temperature, the yeast will not respire to produce the byproducts of anaerobic respiration.

Question 2.
(a) Plants lack a specialised respiratory system. How do they carry out respiratory process? Explain.
(b) The plant roots being underground respire by using which mechanism?
Answer:
(a) The plants do not possess any respiratory system still plants respire. The various parts of the plants like leaves, roots, etc., carry out respiration independently.
These parts take in oxygen from air in different manner and utilise it to obtain energy and give out C02. The leaves of plants possess tiny pores on their surface which is called as stomata. The gaseous exchange during respiration takes place through their stomata.

(b) Roots of the plants respire under the ground. Root cells get oxygen from the air present in the space between the soil particles.
There are several root hairs present on the roots of a plant.
The oxygen from the air (between soil particle) diffuses into root hair and reaches to the cells of the roots. This oxygen is utilised for respiration.

Question 3.
Paheli participated in a 400 m race competition held at her school and won the race. When she came home she had mixed feelings of joy and pain as she had cramps in her leg muscles. After a massage, she was relieved of the pain. Answer the following questions related to the situation.
(a) What can be the possible reasons for the pain in her legs?
(b) Why did she fell comfortable after a massage? [NCERT Exemplar; HOTS]
Answer:
(a) Paheli had cramps in her leg muscles after running. She felt pain in her legs because of accumulation of lactic acid in the leg muscles. Lactic acid is formed due to anaerobic respiration in the muscle cells after heavy exercise or running. After heavy exercise, we require large amount of energy.
To produce more energy to meet the oxygen requirement of muscles, muscle cells perform anaerobic respiration for a short duration.
Lactic acid is formed due to partial breakup of glucose. It gets accumulated in the muscle cells and causes pain and muscle cramps.

(b) The massage or hot water bath gives the relief from muscle cramp or pain, because it improves the circulation of blood leading to increase supply of oxygen to the muscle cells. It helps in complete breakdown of lactic acid into carbon dioxide and water.

Question 4.
It is not wise to sleep under a tree during night. Why?
Answer:
During day, plants photosynthesise in the presence of sunlight and uses CO₂ produced during respiration. During this process O₂ is released as a byproduct and a balance between O₂ and CO₂ is maintained in the atmosphere.

But in the night, plants do not photosynthesise. Plants are unable to use CO₂ during night and produces CO₂ and takes O₂ during respiration.
This leads to the increase in the proportion of CO₂ in the air.
So, if one sleeps under a tree at night, he will have problems in breathing as the amount of CO₂ in the air around will certainly be more than oxygen. Therefore, it is not advisable to sleep under trees during night because the person will suffer from suffocation and feel excess weight on chest.

Question 5.
Observe the figures carefully and answer the following questions.

(a) Which process is being tested in the activity?
(b) What is the result of the activity? Give reasons. [NCERT Exemplar]
Answer:
(a) Exhalation process of respiration is being tested in the activity.
(b) The lime water in test tube B turns milky but water in test tube A remains unchanged. Because CO₂ is present in the exhaled air, it mixes with lime water in test tube B and turns it milky.

Question 6.
(a) Respiratory process occurs in two phases, what are those two major steps of respiration? Describe each one.
(b) Define the term breathing rate.
Answer:
(a) Respiration is the process of breakdown of food to produce energy for performing various functions. It involves two major steps:

Inhalation is the process of taking in of air which is rich in oxygen, inside our body.
Exhalation is the process of giving out of air which is rich in carbon dioxide from our body to the external environment.

(b) The number of times a person breathes, in a minute is called as breathing rate.
An adult human being can inhale or exhale 15-18 times in a minute. It is the average breathing rate of an adult human being. Breathing rate is not constant always.

Question 7.
Observe the given figures as A and B and answer the following questions.

(a) Among both figures identify which A or B indicates the process of inhalation and which shows the process of exhalation?
(b) In the figure label the arrows and indicate the direction of

movement of air
movement of diaphragm
movement of ribs [NCERT Exemplar]

Answer:
(a) Figure A indicates inhalation and figure B indicates exhalation.
(b) Movement of air, diaphragm and ribs are indicated in below figure:

Question 8.
List some animals around you. Now group them as follows:
(a) Animals that can breathe only through skin.
(b) The animal that can breathe through skin as well as through lungs.
(c) The animal that can breathe through lungs.
(d) Animals that can breathe through gills.
(e) Animals that can breathe through spiracle and tracheae? [HOTS]
Answer:
(a) Animals that can breathe only through skin are earthworm and leech.
(b) Animals that can breathe through skin as well as through lungs are frogs.
(c) Animals that can breathe through lungs are buffaloes, human, and dolphins.
(d) Animals that can breathe through gills are tadpole and fish.
(e) Animals that can breathe through spiracles and tracheae are grasshopper, cockroaches, ants, housefly and mosquito.

Question 9.
Palak wants to be a great cyclist. She cycles daily for about 2 hours followed by some exercises. Today, she thought she will cycle for longer and managed it for 41/2 hours. Now she is feeling cramped up and her breathing is disturbed. Her mother took her to hospital where the doctor examined and told her not to push herself more than necessary. Palak understood and promised herself to move show and steadily.
(a) Why did Palak had cramps in her legs?
(b) Is breathing rate also affected after doing long hour of exercise. Why?
(c) When there is not enough oxygen supply,
what happens to body and process of respiration? What values you learn from this? [Value Based Question]
Answer:
(a) Due to extensive exercise, formation of lactic acid occurred as muscles starts to respire anaerobically.
(b) Yes, breathing rate will be faster. Normally we are breathing at a slower rate but during physical activities, to make sufficient amount of O₂ reaching cells we breathe faster.
(c) The body starts respiring anaerobically in the absence of sufficient oxygen. Glucose is partially broken into lactic acid which causes body cramps.
Values learned – We should not force ourselves exercise but not over burn yourself discipline.

Question 10.
A person put some warm water in an aquarium having fish during winter season. He thought that fish will be more comfortable in luke warm water than cold water. But he observed that fishes in the aquarium died. Why the fishes died in warm water? [HOTS]
Answer:
The fishes have special type of organs for respiration called gills. These gills absorbs oxygen dissolved in water and through blood vessels, this oxygen is passed to all the parts of the body. The amount of dissolved oxygen is comparatively less in water than the amount of oxygen in air.
Therefore, the rate of breathing is also high in aquatic animals.
If we add warm water, to the aquarium the dissolved oxygen will dissociate and move into the atmosphere again, leaving the least percentage of oxygen into the water (as it is known that the solubility of gases in water goes down as the temperature rises). Therefore, fishes will have difficulty in breathing in the absence of oxygen and will die.

Question 11.
A group of people were smoking cigarettes in a restaurant. The atmosphere was full of smoke. An old man sitting next to the group asked them to stop smoking while sitting in the premise or move out. They agreed to do so and promised not to repeat then mistake.
Answer the following questions.
(a) Write any three hazards of smoking.
(b) Can smoking also affect the person who does not smoke?
(c) Do you support the group’s decision to not smoke in public or indiviually. What values do we understand
from here. [Value Based Question]
Answer:
(a) Smoking is very injurious for the respiratory system. It harms lungs.

It causes blockage in respiratory tract.
It leads to lung cancer.
It can cause disease like asthma and heart diseases.

(b) Yes, smoking affects people who are passive smokers, i.e. those present nearby smokers.
(c) Yes, the people should bot smoke in public areas as it can cause discomfort to others.
The values we understand are obedience, respect elders and healthy habits.

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CHAPTER – 9 Soil | CLASS 7TH | NCERT SCIENCE IMPORTANT QUESTIONS & MCQS | EDUGROWN

SCIENCE IMPORTANT QUESTIONS & MCQS FOR CLASS 7th

Chapter - 9 Soil

MCQs

Question 1.
Which one of the following is a step in the formation of soil?
(a) Earthquakes or volcanic eruptions
(b) Weathering of rocks
(c) Addition of humus
(d) All are involved in the formation of soil

Answer

Answer: (d) All are involved in the formation of soil

Question 2.
In which horizon of soil minerals are found?
(a) A
(b) B
(c) C
(d) None of these

Answer

Answer: (b) B

Question 3.
Which physical property of soil is important to us?
(a) Texture
(b) Water holding capacity
(c) Both of these
(d) None of these

Answer

Answer: (c) Both of these

Question 4.
Which of the following type of soil will form a colloidal solution when suspended in water?
(a) Clay
(b) Silt
(c) Sand
(d) Gravel

Answer

Answer: (a) Clay

Question 5.
Which factor influences soil formation?
(a) Climate
(b) Vegetation
(c) Parent rock
(d) All of these

Answer

Answer: (d) All of these

Question 6.
The proportion of sand, silt and clay in a soil sample determines
(a) structure
(b) texture
(c) nutrient potential
(d) fertility level

Answer

Answer: (b) texture

Question 7.
The microorganisms present in the soil require moisture (water) and nutrients for growth and survival. Choose from the options below the habitat (place) where the soil has plenty of water and nutrients.
(a) Desert
(b) Forest
(c) Open field
(d) Cricket ground

Answer

Answer: (b) Forest

Question 8.
Availability of water and minerals in the soil for maximum absorption by roots is in the:
(a) B-horizon
(b) C-horizon
(c) A-horizon
(d) Surface of soil

Answer

Answer: (c) A-horizon

Question 9.
Soil conservation measures are mainly aimed at protecting which of the following?
(a) Plants
(b) Topsoil
(c) Sub soil
(d) Soil organisms

Answer

Answer: (b) Topsoil
Soil conservation measures mainly aim at protecting topsoil, which is rich in humus and nutrients making it fertile to grow plants.

Question 10.
Read the following statements with reference to soil:
(i) Weathering is a very fast process of soil formation.
(ii) Percolation of water is faster in sandy soils.
(iii) Loamy soil contains only sand and clay.
(iv) Top soil contains the maximum amount of humus.
Choose the correct statements from the above.
(a) (ii) and (iv)
(b) (i) and (iii)
(c) (ii) and (iii)
(d) (i) and (ii)

Answer

Answer: (a) (ii) and (iv)

Match the following:

Column A	Column B
(i) Silt	(a) Particle size less than 0.005 mm
(ii) Gravel	(b) Particle size between 0.005 and 0.05 mm
(iii) Sand	(c) Particle size between 0.05 and 2.00 mm
(iv) Clay	(d) Particle size greater than 2.00 mm
(v) Wheat, gram and paddy	(e) Sandy loam soil
(vi) Cotton	(f) Clayey soil
(vii) Pots, toys and statues	(g) Clay and loam soil

Answer

Answer:

Column A	Column B
(i) Silt	(b) Particle size between 0.005 and 0.05 mm
(ii) Gravel	(d) Particle size greater than 2.00 mm
(iii) Sand	(c) Particle size between 0.05 and 2.00 mm
(iv) Clay	(a) Particle size less than 0.005 mm
(v) Wheat, gram and paddy	(g) Clay and loam soil
(vi) Cotton	(e) Sandy loam soil
(vii) Pots, toys and statues	(f) Clayey soil

Fill in the blanks:

1. Soil is formed by ……………… of rocks.

Answer

Answer: weathering

2. A dark soil is usually rich in ………………

Answer

Answer: organic matter/humus

3. The physiochemically active portion of soil is ………………

Answer

Answer: top soil

4. Soil erosion can be stopped by ………………

Answer

Answer: plantation

5. Erosion involves movement of ……………… from one place to other.

Answer

Answer: soil

6. Soil is of different types: clayey, loamy and ………………

Answer

Answer: sandy

7. ……………… is a section through different layers of the soil.

Answer

Answer: Soil profile

8. ……………… soil is used to make pots, toys and statues.

Answer

Answer: Clayey

Choose the true and false statements from the following:

1. Upper portion of soil always contains air.

Answer

Answer: True

2. Percolation rate of water is highest in the clayey soil and least in the sandy soil.

Answer

Answer: False

3. Clay and loam are suitable for growing wheat, gram and paddy.

Answer

Answer: True

4. Cotton is grown in sandy loam soil.

Answer

Answer: True

5. Capacity to hold water is more in sandy soil than clayey soil.

Answer

Answer: False

6. Clayey soil is used for making pots, toys and statues.

Answer

Answer: True

7. Erosion of soil is more severe in areas of high vegetation.

Answer

Answer: False

8. Polythene bags and plastics pollute the soil.

Answer

Answer: True

Imoprtant Questions

Question 1.
In how many groups the soil has been categorised? Name them.
Answer:
The soil has been categorised into four major groups, i.e.

clay
silt
sand
gravel

Question 2.
Which soil is considered to be the most fertile and used for growing crops?
Answer:
Loamy soil is the most fertile soil and used for growing crops.

Question 3.
Which type of soil absorbs more water but allows less wateMo percolate?
Answer:
Clayey soil absorbs more water but allows less water to percolate

Question 4.
Give the formula to calculate the absorption percentage.
Answer:
The absorption percentage of water can be calculated by the formula given below
Percentage of water absorb = Amount of water absorbed (in mL) Amount of soil (in gm) ×100

Question 5.
When we add some dry soil to the water in a glass and stir it, bubbles are observed from the soil. What causes these bubbles to raise? [HOTS]
Answer:
When dry soil is added in the water in a glass and stir it, bubbles appear. These bubbles are caused due to the air present in between the soil particles.

Question 6.
What is weathering?
Answer:
Weathering is a natural process by which huge rock is broken down into tiny particles but at a very slow rate.

Question 7.
There is shimmering of air just above the soil during hot summer day. What does the term shimmering indicate? [HOTS]
Answer:
The term shimmering means that the air shines with a slightly shaking light.

Question 8.
Draw a diagram to show the different layers of soil.
Answer:
Soil Class 7 Extra Questions Science Chapter 9 1

Question 9.
Name two soil types used for cultivation.
Answer:
Clayey soil and loamy soil are rich in humus and are suitable for growing plants like wheat and gram.

Question 10.
Soil has particles of different sizes. Arrange the words given below in decreasing order of their particle size. Rock, clay, sand, gravel, silt [NCERT Exemplar]
Answer:
The soil particles with the decreasing order of their particle sizes can be shown as
Rock > gravel > sand > silt > clay

Question 11.
There are two components of soil one that comes from living thing and other from non-living thing. What are these two components?
Answer:
The two major components of soil are weathered rock particles, i.e. non-living components and humus that consists of living organisms like fungi, bacteria, worm, insects, etc.

Question 12.
It is necessary to ban the use of polythene bags and plastics. Do you agree? If yes, why? [HOTS]
Answer:
Polythene bags and plastics pollute the soil as they kill the organisms living in the soil.
That’s why, it is necessary to ban the use of polythene bags and plastics.

Question 13.
List the substances which pollute the soil.
Answer:
The substances which pollute the soil are polythene bags, plastics, waste products, chemicals, pesticides, etc.

Question 14.
A special kind of soil is used for making matkas and surahis. Name it. [HOTS]
Answer:
Clayey soil is used to make matkas and surahis.

Question 15.
Explain the term humus that is generally found in the uppermost layer of soil.
Answer:
The rotting dead matter in the soil is called humus.

Question 16.
Can we make toys with the soil obtained from a field? Explain.
Answer:
No, soil from a field cannot be used to make toys. In order to make toys, the soil should be clayey.

Question 17.
The percolation rate varies from soil to other soil. Which soil would have the highest and least percolation rate?
Answer:
Percolation rate of water is highest in the sandy soil, while the lowest in the clayey soil.

Question 18.
How can a farmer convert acidic soil into neutral soil? [NCERT Exemplar]
Answer:
The farmer can convert acidic soil into neutral soil by adding a small quantity of quicklime or slaked lime solution to the soil.

Question 19.
Do all types of soil absorb water to the same extent? Give reason for your answer.
Answer:
No, it is because different types of soil has different absorbing capacity of water.

Question 20.
For planting rice, which kind of soil would be most suitable?
Answer:
For planting paddy (rice), clayey soil that is rich in organic matter and have a good water retaining capacity is ideal.

Soil Class 7 Science Extra Questions Short Answer Type Questions

Question 1.
The soil is said to be inseparable part of our life. Why?
Answer:
Soil is one of the most important natural resources. It is the uppermost layer of earth’s crust which is blackish-brown in colour. Major functions of the soil are:

It supports plant growth by holding the roots firmly and supplying water and nutrients to the plants.
It acts as a natural habitat for many organisms like earthworm, fungi, bacteria, ants, etc.
It is also essential for agriculture which provides us food, clothing and shelter for all.
It supplies water and nutrients to plants.

Therefore, we can say that the soil is inseparable part of our life.

Question 2.
Suppose certain sample takes 120 min for 960 mL water to percolate into the soil. Calculate the rate of percolation of water.
Answer:
Given, amount of water = 960 mL
Time taken to percolate =120 min
The rate of percolation will be
= Amount of water (in mL) Percolation time (in min) =960mL120min=8mL/min
Percolation rate = 8 mL/min

Question 3.
Locate the following zones given as boxed items in figure which shows a diagram of soil profile.
Topsoil, subsoil, bedrock [NCERT Exemplar]
Soil Class 7 Extra Questions Science Chapter 9 2
Answer:
It is the uppermost layer of soil and is usually dark in colour because of the presence of minerals and humus in it. It provides the nutrients in plants, since the roots of most plants are confined to this layer. Humus is the dark brown coloured layer which consists of dead, rotting remains of plants and animals.
Soil Class 7 Extra Questions Science Chapter 9 1
This layer of soil lies just below the topsoil. It is made up of slightly bigger rock particles than that of the topsoil. It does not have much humus and is lighter in colour than topsoil. It is somewhat harder and more compact than the topsoil. This layer is less fertile than topsoil and contains few living organisms. Subsoil is rich in minerals and iron oxides.

Below the C-horizon unweathered solid rock is found which is called as bedrock. It is non-porous and can produce the soil over a long period of time. Rainwater gets collected over it to form water table.

Question 4.
A student visits two types of field and observes that soil from field A has high percolation rate of water, while soil from field B has low percolation rate. In field B, paddy crop was grown while in field A, there was no standing crop. Name two types of soil present in two fields. [HOTS]
Answer:
Soil in field A is sandy soil while in field B soil is clayey soil which has low percolation rate and water-logging is seen. Since, paddy requires lot of standing water, therefore it is grown in field B.

Question 5.
Describe how clayey soil is useful for crops?
Answer:
Clayey soil is useful for the crops because

it has good water retaining capacity.
it is rich in humus.
it is fertile in nature.

Crops like wheat and rice can be easily grown in clayey soil.

Question 6.
Read the following statements and give the appropriate terms for each of them.
(a) The process of breakdown of rocks by the action of wind, water, sunlight.
(b) Removal of topsoil during heavy rains or strong winds.
(c) Accumulation of wastes in the soil generated by human activity which alter the features of soil.
(d) The process of movement of water into deeper layers of soil. [NCERT Exemplar]
Answer:
The terms for the above described statements are as follows
(a) Weathering
(b) Soil erosion
(c) Soil pollution
(d) Percolation

Question 7.
Describe the different type of soil.
Answer:
There are three different types of soil

Sandy soil containing sand particles in them.
Clayey soil contains clay particles with small amount of humus in it. It is a fertile soil.
Loamy soil is a mixture of sand, clay silt and humus. It is a fertile soil

Question 8.
Rajasthan is a desert state in India. Once while travelling to Rajasthan by train, Boojho observed several streams and rivulets of rainwater during the journey but to his surprise, he did not see streams of water in the desert region even during rains. Help Boojho to find a suitable explanation for this. [NCERT Exemplar; HOTS]
Answer:
Deserts are made up of sand, thus when the rainwater falls on land, it percolates immediately downwards in the spaces between sand particles. So, the streams of water in desert region are not visible even during rainy season.

Question 9.
A man digging a pit found that he could dig with ease initially but digging became difficult as he went deeper. He could not big beyond a depth 5 feet. Provide a suitable scientific explanations. [NCERT Exemplar; HOTS]
Answer:
The man digging a pit could dig with ease initially because of the presence of topsoil and subsoil (mainly comprising of humus and nutrients). But as he digs deeper, he finds it difficult to dig beyond a depth of 5 feet as lower layers are made up of small partially weathered rocks with cracks, crevices and with bedrock which make it hard to dig.

Question 10.
Continuously water-logged soils are disadvantageous for plant growth. Why? [NCERT Exemplar]
Answer:
Roots although underground possesses living cells that require oxygen for respiration and production of energy. They absorb oxygen that is present in the spaces between soil particles. But in water-logged soils, water occupies spaces between soil particles and pushes the oxygen out into the atmosphere. Thus, roots are deprived of oxygen and this affects the plant growth.

Question 11.
Is it a good practice to remove grass and small plants that are growing in an open, unused field? Give reason to support your answer. [NCERT Exemplar; HOTS]
Answer:
No, it is not a good practice to remove grass and small plants growing in an open, unused field because the plants cover the soil surface. Their roots bind the soil particles, holding and adhering them in place. It helps in preventing the topsoil from being washed off during heavy rain, floods and winds.
In this way, soil erosion is prevented and topsoil layer is preserved for growing more plants.

Question 12.
Observe the following figure and answer the following questions.
Soil Class 7 Extra Questions Science Chapter 9 3
(a) Which is the heaviest rock material?
(b) Which is the lightest soil component?
(c) Why different layers of soil component are formed?
Answer:
(a) Gravel is the heaviest rock material.
(b) Humus is the lightest soil component which floats on the water surface.
(c) The soil component forms various layer one above the other according to the size of soil particle.

Question 13.
During the summer vacations, Gaurav visited his native village. He observed that farmers were using pesticides in their field. He contacted the village head and explained him the effects of such substances in causing soil pollution. Next day, the village head called a meeting of all the villagers and convinced the villagers not to use chemicals and pesticides.
(a) Why is there a ban to demand the polythene bags and plastics.
(b) List some substances which pollute the soil.
(c) What are the values shown by Gaurav? [Value Based Question]
Answer:
(a) It is because these substances pollute the soil. They also kill the organisms living in the soil.
(b) Substances which pollute the soil are a number of waste products, chemicals, pesticides, polythene bags and plastics.
(c) Alertness, responsibility and ecofriendly nature.

Question 14.
Write the difference between rate of percolation and the amount of water retained.
Answer:
Percolation property of any material is linked to its porosity. Different soils have different porosity.
Therefore, water percolates differently through different soil.
Percolation rate of water in the soil = Volume of water percolated Time taken for percolation
Whereas water retaining capacity of a soil is described in terms of the amount of water absorbed by a particular type of soil. High water retaining capacity means higer water absorption.

Question 15.
Why is soil erosion relatively less in dense forests as compared to barren, open fields? [NCERT Exemplar; HOTS]
Answer:
In dense forests, the tree cover (canopy) prevents rainwater from directly falling on the ground/soil. Also roots of the vegetation bind the soil particles and hold them together. As a result, soil erosion is minimised.
But in barren, open fields, the soil is exposed to the falling rain. The soil particles become loose due to the impact of raindrops and the flow of water carries them away. The flowing water further erodes the soil surface aggravating erosion.

Question 16.
Gardeners gently dig up the soil around the roots of garden herbs (plants) frequently. Give reasons. [NCERT Exemplar. HOTS]
Answer:
A gardener often gently digs up the soil around the roots of garden plants or herbs for following reasons

It enables easy root growth.
For easier percolation of water.
For aerating the soil enabling air to get into deeper layers of soil.
For removing the weeds.

Soil Class 7 Science Extra Questions Long Answer Type Questions

Question 1.
Explain through an activity that soil has moisture in it.
Answer:
Take a plastic funnel and a filter paper. Fold the filter paper and place it in a plastic funnel. Now keep the funnel (with filter paper) in a beaker. Take some dry powdered soil and weigh it on a balance.
Note the mass of the soil taken. Now pour this weighed soil into the filter paper fixed in a funnel.
Soil Class 7 Extra Questions Science Chapter 9 4
Take a measuring cylinder and fill it with water. Note the initial volume of water in the measuring cylinder. Take water from measuring cylinder with the help of a dropper and pour it drop by drop on the soil kept in the funnel. Be careful that water should not fall at one spot on the soil but should be poured uniformly all over the soil. Keep pouring water till it starts dripping from the lower end of the funnel.
Dripping of water from funnel shows that the soil taken on the filter paper has absorbed the maximum amount of water. Note the final volume of water that is left unused in the measuring cylinder.

By substracting the amount of water left in the measuring cylinder from the amount of initial volume of water taken in the measuring cylinder. We will get the volume of water absorbed by the soil which was taken on filter paper in the funnel. The difference in two reading gives the amount of water retained by the soil. The calculation can be done as follows:
Suppose, the mass of the soil taken = 50 g
Let the initial volume of water U = 100 mL
and final volume of water V = 60 mL
Therefore, the volume of water absorbed by the soil = (U- V) mL = (100 – 60)mL = 40 mL
and weight of the water absorbed by the soil = (U – V)Q = (100 – 60) g = 40 g
Therefore, the percentage of water absorbed = =(U−V50×100)=4050×100=80%
When we perform this activity with different soil samples, we will see that.

Sandy soil will absorb less water and allows more water to percolate.
Clayey soil will absorb more water but allow less water to percolate.
Sandy soil will absorb less water than clayey soil because of the large spaces between the soil particles. The area where, there is a lot of clay in the soil, stagnant water collects above the soil whenever it rains.

Question 2.
Design an activity to show the soil erosion on a barren land.
Answer:
Strong wind and rain can cause soil erosion from the barren land. This can be shown by performing an activity.
Take a wooden block and place some soil or sand on it. Keep an ice-cube tray at one end of the wooden black. Take a small battery-operated fan or hair dryer and hold it at the other end of the black near sand so that it blows the sand into the tray.

We will observe that when the fan blows it causes sand or soil particles to move and these get land in the various compartment of the ice-cube tray. This activity shows that the wind blows the soil on a barren land and may cause soil erosion.
Soil Class 7 Extra Questions Science Chapter 9 5

Question 3.
The contamination of soil with waste materials causes soil pollution. Does the use of pesticides in agriculture also contribute to the soil pollution? Explain.
Answer:
The contamination of soil with waste materials especially used polythene bags and plastics, pesticides, fertilisers, acid rain industrial chemical wastes, etc., is called soil pollution.

Pesticides are the poisonous chemical substances which are sprayed on standing crops to save them from the harmful insects and diseases. Some of these pesticides also mix up with the soil in the fields and pollute it. The grains, fruits and vegetables grown in this polluted soil contain pesticides. When we eat such contaminated grains, fruits or vegetables, the pesticides present in them damage our health also.

Question 4.
A soil sample was taken from an agricultural land and was weighed. The mass of the soil was found to be 50 g. 100 mL of water was taken in a measuring cylinder and added into the soil sample. The soil absorbed 80 mL of water and rest left in the measuring cylinder. Calculate the absorption rate of water by the soil. [HOTS]
Answer:
The absorption rate of water by soil can be calculated by the formula as follows:
Soil Class 7 Extra Questions Science Chapter 9 6
40% of the water has been absorbed by the soil.

Question 5.
(a) Soil has various important component. Write them.
(b) Arrange the following rock particles which occur in soil in the increasing order. Silt, clay, gravel, sand.
(c) Observe the following figure. What does this figure show?
Soil Class 7 Extra Questions Science Chapter 9 7
Answer:
(a) The various important component of soil are air, water, rock particles, minerals, humus and living organisms like bacteria, fungi, worms (earthworm), rodents, insects (ant and beetle), etc.
(b) The increasing order of rock particles are
Clay → Silt → Sand → Gravel
(c) The figure shows waste material like polythene bags, plastics, glass and metal objects are dumped which causes soil pollution.

Question 6.
In towns and cities, generally, the borewells have to be dug very deep to get water as compared to borewells dug in villages. Give suitable reasons. [NCERT Exemplar; HOTS]
Answer:
The borewells have to be dug very deep to get water as compared to those in villages because

excessive use of water depletes the groundwater.
towns and cities have asphalted roads and vast areas of soil are concreted. As a result, rainwater cannot percolate to recharge groundwater and the groundwater level further decreases. Villages have larger areas of open soil surface and fewer asphalted roads and concrete surfaces.

Thus, larger soil surface area is available for rainwater to percolate into the soil easily and recharge the groundwater. As a result, even shallow borewells yield water.

Question 7.
Soil erosion does not occur easily where the land is covered by vegetation. Do you agree? Explain.
Answer:
Yes, soil erosion does not occur easily where the land is covered by vegetation (trees and other plants). It occurs easily in those areas of land which are not covered by vegetation (trees and other plants) or have very little vegetation. If there is vegetation on land,

then the roots of vegetation growing in the soil bind the particles of topsoil firmly. Due to this, the blowing wind and flowing rainwater are not able to carry away topsoil and hence soil erosion does not occur.
then much of the falling rain hits the trees and plants before it hits the soil. In this way, the cover of vegetation softens the effect of heavy rains on the soil.

Question 8.
The raw and baked soil differs from each other. How they are different? How can you prepare matkas from soil? [HOTS]
Answer:
Raw soil differs from baked soil. The raw soil is white or dull blackish coloured soil. It contains water and air in it and can be moulded.

Baked soil is the heated raw soil which lost its water molecule due to heating and becomes red. Once the soil gets heated, it cannot be moulded into other form. Clay soil is used for making matkas, toys, pots, etc. The soil is kneaded along with horse dung to make best quality of raw clay soil. This kneaded soil is then placed on the wheel and appropriate shape is given. The final shape of the material is given with hands. The pots and matkas are then kept for drying for three days. These items are baked at high temperature after drying in air and then coloured.

Question 9.
During a field trip, some students visited an agricultural farm and saw a few birds eating earthworms. They enjoyed the scene and then they also started picking and killing the earthworms for pleasure. Seeing the crowd of students in a corner, the teacher rushed to them to see the matter and objected to their action. Anshul, one of the student asked the reason.
Teacher smiled and explained him that an earthworm living in the soil is very beneficial for farmers. Anshul wondered whether there were other organisms also in the soil. The teacher appreciated him and explained.
(a) Mention the importance of earthworm.
(b) List some organisms living in soil.
(c) What are the values shown by Anshul? [Value Based Question]
Answer:
(a) An earthworm helps in making the rich humus in soil.
(b) Ant, earthworm, termites, milipede, centipede, etc.
(c) Curiosity to learn and scientific attitude.

Question 10.
A soil sample having mass of 200 g was taken from garden.This soil was dried completely in the oven and again weight. The weight of the soil now was found to be 170 g. Calculate the percentage of water or moisture content present in the sample soil. [HOTS]
Answer:
The moisture content of the soil can be calculated by the formula as follows:
= Mass of water in soil Original mass of soil ×100
Given, Original mass of soil = 200 g
Mass of soil after drying =170 g
Then mass of water in soil will
= 200 – 170 = 30 g
The percentage of water in soil will be
30g200g×100=15%

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CHAPTER – 8 Winds, Storms and Cyclones | CLASS 7TH | NCERT SCIENCE IMPORTANT QUESTIONS & MCQS | EDUGROWN

SCIENCE IMPORTANT QUESTIONS & MCQS FOR CLASS 7th

Chapter - 8 Winds, Storms and Cyclones

Question 1.
In which year was Orissa hit by a cyclone?
(a) 1999
(b) 2000
(c) 2001
(d) 2004

Answer

Answer: (a) 1999

Question 2.
Leaves of trees, banner or flags flutter when wind is blowing. Why?
(a) Air occupies space
(b) Air is a mixture of gases
(c) Air exerts pressure
(d) Air is colourless

Answer

Answer: (c) Air exerts pressure

Question 3.
When we blow over a paper strip it goes upward as shown in the figure given below. why?

(a) Blowing over the paper reduces the air pressure above the strip
(b) Blowing over the paper increases the air pressure above the strip
(c) None of these is a correct reason
(d) The strip will not go upward at all

Answer

Answer: (a) Blowing over the paper reduces the air pressure above the strip

Question 4.
Following are precautions one must take in case a storm is accompanied by lightning.
(i) Do not take shelter under a tree.
(ii) Do not take shelter under an umbrella with a metallic end.
(iii) Do not take shelter in open garages, storage sheds, etc.
(iv) Do not take shelter in a bus in the open.
Which one of these is not correct?
(a) (i)
(b) (ii)
(c) (iii)
(d) (iv)

Answer

Answer: (d) (iv)

Question 5.
Which of the following places is most likely to be affected by a cyclone?
(a) Mumbai
(b) Puri
(c) Goa
(d) Porbandar

Answer

Answer: (b) Puri

Question 6.
A fire alarm usually detects smoke in case of fire. Where should such an alarm be placed in a room? (NCERT Exemplar)
(a) Near the door
(b) On the floor
(c) On any wall
(d) On the ceiling

Answer

Answer: (d) On the ceiling

Question 7.
The winds from oceans carry water and bring rain. These winds are called
(a) typhoon
(b) monsoon
(c) cyclone
(d) none of these

Answer

Answer: (b) monsoon

Question 8.
What is a cyclone?
(a) Winds from the oceans carrying water
(b) Very low pressure system with very high speed winds revolving around it
(c) Dark funnel shaped cloud that reaches from the sky to the ground
(d) None of these

Answer

Answer: (b) Very low pressure system with very high speed winds revolving around it

Question 9.
Pick the odd one out
(a) Cyclone
(b) Hurricane
(c) Monsoon
(d) Typhoon

Answer

Answer: (c) Monsoon

Question 10.
A cyclone warning can be issued
(a) 48 hours in advance
(b) 12 hours in advance
(c) 6 hours in advance
(d) 24 hours in advance

Answer

Answer: (d) 24 hours in advance

Match the following:

Column A	Column B
(i) Wind	(a) Dark funnel shaped cloud
(ii) Monsoon	(b) Very low pressure system with very high speed winds revolving around it
(iii) Thunderstorm	(c) measures the speed of wind
(iv) Cyclone	(d) develops in India very frequently
(v) Tornado	(e) Moving air
(vi) Anemometer	(f) Winds carrying water

Answer

Answer:

Column A	Column B
(i) Wind	(e) Moving air
(ii) Monsoon	(f) Winds carrying water
(iii) Thunderstorm	(d) develops in India very frequently
(iv) Cyclone	(b) Very low pressure system with very high speed winds revolving around it
(v) Tornado	(a) Dark funnel shaped cloud
(vi) Anemometer	(c) measures the speed of wind

Fill in the blanks:

1. Moving ………………… is called a wind.

Answer

Answer: air

2. Air exerts …………………

Answer

Answer: pressure

3. Increased wind speed is accompanied by ………………… air pressure.

Answer

Answer: reduced

4. The warm air is ………………… than cold air.

Answer

Answer: lighter

5. Wind currents are generated due to ………………… heating on the earth.

Answer

Answer: uneven

6. Very pressure system with very ………………… speed winds revolving around it is called a cyclone.

Answer

Answer: low,high

7. A dark funnel shaped ………………… that reaches from the sky to the ground is called a tornado.

Answer

8. ………………… and ………………… have made possible to issue a cyclone alert, i.e., 48 hours in advance.

Answer

Answer: Satellites, radars

Choose the true and false statements from the following:

1. Air around us exerts pressure.

Answer

Answer: True

2. Air contracts on heating and expands on cooling.

Answer

Answer: False

3. As cool air rises air pressure at that place is reduced and the warmer air moves to that place.

Answer

Answer: False

4. Winds carrying water vapours bring rains.

Answer

Answer: True

5. High speed winds and air pressure differences can cause cyclones.

Answer

Answer: True

6. Cyclones are beneficials to the people living in coastal areas.

Answer

Answer: False

7. Tornadoes are very frequent in our country.

Answer

Answer: False

8. It has become easier to monitor cyclones with the help of advanced technology like satellites and radars.

Answer

Answer: True

Question 1.
Why is Chandigarh unlikely to be affected by a cyclone? [NCERT Exemplar]
Answer:
Chandigarh is unlikely to be affected by a cyclone because it is not near to the sea or an ocean.

Question 2.
Discuss the major cause of winds.
Answer:
Wind currents are generated due to uneven heating on the earth. It may be between equator and pole and between land and water.

Question 3.
Name the ocean which is mainly responsible to bring rain bearing monsoon winds to Kerala coast in June every year. [NCERT Exemplar]
Answer:
An Indian ocean is mainly responsible to bring rain bearing monsoon winds to Kerala coast in June every year.

Question 4.
Briefly describe the effect of heat on air pressure.
Answer:
The heat causes air to expand and occupies more space. It becomes lighter. That’s why, warm air is lighter than the cold air.

Question 5.
To expel hot air out of the kitchen, A has an exhaust fan fitted on the window of her kitchen and B has a similar exhaust fan fitted on the wall near the ceiling of her kitchen. Which of the exhaust fan will expel the hot air more effectively? Explain why. [NCERT Exemplar; HOTS]
Answer:
B’s exhaust fan will expel the hot air more effectively because hot air rises up and her fan is at greater height than A’s.

Question 6.
Enlist the other names of cyclone.
Answer:
Hurricane and typhoon are the other names of cyclone.

Question 7.
Suggest some precautions to be taken to prevent the roof of a tin sheet from flying away during a fierce wind storm. [NCERT Exemplar]
Answer:
Some precautions are

Put heavy stones on it.
Screw it tight.

Question 8.
Name the instrument which is used to measure the speed of wind.
Answer:
Anemometer is used to measure the speed of wind.

Question 9.
A flag mounted on a flag post near the sea coast flutters in the direction of sea. At what time of the day does this happen — at mid-night or in the afternoon? [NCERT Exemplar]
Answer:
In the mid-night, the wind blows from land to sea. So, in the mid-night flag mounted on a flag post near the sea coast flutters in the direction of sea.

Question 10.
Figure shows a diagrammatic representation of trees in the afternoon along a sea coast. State on which side is the sea, A or B? Give reasons for your choice. [NCERT Exemplar]

Answer:
In the afternoon, the wind blows from sea to land.
As pressure on the land is less than the pressure above sea, so the sea is on B side.

Question 11.
Name the factor responsible for the increase of speed of wind or cyclones.
Answer:
Factors like wind speed, wind direction, temperature and humidity contribute to the development of cyclones.

Question 12.
Name some cyclones that occurred in the past.
Answer:
Hugo, Katrina, Rita, Hud-Hud and Phailin are the various types of cyclones that occurred in the past.

Question 13.
Can you say why smoke always rises up?
Answer:
As we know that smoke is the combination of hot airs and hot air becomes light weight with respect to cold air. Thus, it always rises up.

Question 14.
In the wind flow pattern, it can be found that the wind shown is not in the exact North-South direction. Explain why.
Answer:
It is because the winds would have blown in the North-South direction either from North to South or from South to North. A change in direction is however caused by the rotation of the earth.

Question 15.
Monsoon winds are helpful. Do you agree?
Answer:
The monsoon winds carry water and it rains. Clouds bring rain and give us happiness. Farmers in our country depend mainly on rains for their harvests. So, monsoon winds are helpful.

Winds, Storms and Cyclones Class 7 Science Extra Questions Short Answer Type Questions

Question 1.
Paheli kept an empty bottle made of plastic inside a refrigerator. After few hours, when she opened the refrigerator, she found the bottle had collapsed. Explain the possible reason. [NCERT Exemplar; HOTS]
Answer:
On cooling the air, contraction of air takes place. The air inside the bottle contracts due to low temperature. Hence, the bottle collapses due to the outside pressure.

Question 2.
Mention an example when the cyclone hit a part of India and how much destruction was caused due to it.
Answer:
Orissa (a part of India) was hit by cyclone in 18th October 1999. The wind speed was 200 km/h and smashed 45000 houses making 700000 people homeless. Another cyclone hit the Orissa again an 29th October with the wind speed of 260 km/h. Thousands of people lost their lives and property worth crores of rupees was destroyed.

Question 3.
When strong/high speed wind blows, an umbrella held upright at times gets upturned. Explain the reason. [NCERT Exemplar]
Answer:
High speed wind passing over the umbrella creates low pressure above the umbrella with respect to below of it. Therefore, the umbrella upturns.

Question 4.
Give three precautions that should be taken to protect oneself from the thunderstorm. [Value Based Question]
Answer:
The following three precautions must be taken to protect oneself from the lightning of thunderstorm

Do not take shelter under an isolated tree.
Do not lie on the ground
Do not take shelter under an umbrella with a metallic end.

Question 5.
Explain thunderstorm and how are they produced.
Answer:
The swift movement of the falling water along with the rising warm air producing sound, lightning, heavy rain and strong wind is called thunderstorm.

Question 6.
Name some effective safety measures against cyclone?
Answer:
On the part of government

Cyclone forecast and warning system must be installed.
Information about cyclone should be given to the people in time through rapid communication system.
Construction of cyclone-shelter in cyclone-prone areas.
Administrative arrangement should be taken to move people faster to safer places.

On the part of the people

People should follow the essential guidelines provided by the agencies through TV radio, phones, etc.
Proper arrangement should be made to shift the essential household goods, domestic animals, etc. to the safer places.
Avoid driving on road which are under water because flood might have damaged the road.
Phone numbers of all the emergency services like police, fire brigade, hospitals, etc. should be kept ready.

These are produced by the dark clouds which form at fairly low altitude in the atmosphere.

Question 7.
Tornado is different from a cyclone. Briefly explain Tornado. What destructions does it cause?
Answer:
These are formed over sea and are called water spouts. Tornado develops from thunderstorm and are formed mostly on the land. These are violent and can reach the speeds of more than 500 km/h destroying everything in their path. These are not very common in India but occurs in Canada and USA.

Most of the tornadoes are weak. When the warm air from the earth’s surface rises up, it whirls around it and causes very high speed winds. These are much smaller than cyclones, i.e. from a few metre to a few hundred metre but the wind speed can rise as high as 500 km/h. The funnel of tornado sucks up everything at its base like dust, debris, cars, trees and even houses.

Question 8.
The advanced technologies issue the alerts and warnings of unexpected storm. Comment.
Answer:
The technologies that include satellites and radars issue the information of expected storm in advance in the form of cyclone warnings. It is issued in two stages, i.e. a cyclone alert or cyclone watch is issued 48 h in advance of any expected storm and cyclone warning is issued 24 h in advance. The message is broadcasted every hour or half hour when a cyclone is nearest the coast.

Question 9.
Monsoon brings rain. Explain the formation of monsoon.
Answer:
During summer, when the land gets warmed and temperature of land becomes higher than that of water in ocean. The air above the land gets heated and rises. Therefore, the cold wind flows from the ocean towards the land. These are monsoon winds which bring water and cause rain.

Question 10.
Due to uneven heating of land and ocean water what happens in the following season?
(a) In winter season
(b) In summer season [HOTS]
Answer:
Due to uneven heating of land and ocean water
(a) In winter season The uneven heating of land and water generates winds from the North-West colder land which carry little water. It brings small amount of rain in winter season.
(b) In summer season The uneven heating of land and ocean water generates wind from the South-West direction. These winds carry lot of water from the Indian ocean.

Question 11.
Rohan was very happy that there was his birthday. He was decorating the room by blowing balloons. He was wondered that most of his balloons burstd. He rushed to his father and asked the reason. His father smiled and explained.
(a) Can you explain the region that why his balloons get burst?
(b) What can be conclude from the condition mentioned?
(c) What are the values shown by Rohan? [Value Based Question]
Answer:
(a) When Rohan blows air into the balloon, the balloon gets inflated due to the pressure exerted by air. But, Rohan observed that most of his balloons burstd. The reason behind it was, he overfilled the air into the balloon. The warm air gets expanded inside the balloon and exerted more and due to the more pressure on the walls of the balloon, balloons burstd.
(b) From the condition mentioned above, it can be concluded that air expands on heating.
(c) Curiosity to learn and scientific attitude.

Question 12.
How are the pressure difference created in nature?
Answer:
Pressure difference is created in the nature by the heat of the sun. When it falls on the earth surface, the surface of the earth gets heated and air above it also gets warm and becomes light weight and moves upward. Thus, the pressure difference is created.

Question 13.
Describe the following terms briefly.
(a) Trade winds
(b) Wester lies
(c) Polar winds
Answer:
(a) The permanent wind that blows towards the equator from North to South are called trade winds.
(b) The wind blowing towards 60° N and 60° S latitudes are called wester lies.
(c) The set of wind blowing from the cold polar regions towards 60° N and 60° S latitudes are called polar winds.

Question 14.
A flat in Mumbai with a balcony facing the sea has some clothes hung on a clothes line in the balcony. Towards which direction, the clothes will be blown in the afternoon? Explain it. [NCERT Exemplar; HOTS]
Answer:
As during the afternoon, the land becomes hot which ultimately creates hot air above it and we know that hot air rises up and there is low pressure created. Thus, winds from sea start blowing towards the land and the clothes will be blown towards the house because sea breeze blowing towards the land.

Question 15.
Briefly explain what are cyclones and how are they formed.
Answer:
High speed winds and air pressure difference can cause cyclones.They are formed when water vapour changes back to liquid by the release of heat. This heat warms air around and it rises to move up and more air rushes to the vacant place. Thus, a cycle is formed which have low pressure and very high speed of air.

Winds, Storms and Cyclones Class 7 Science Extra Questions Long Answer Type Questions

Question 1.
The picture in figure shows tree line along the sea coast on an tops are permanently bent in one direction. Are the trees bendisland near the equator. As shown, the tree towards the sea or away from it? Explain. [NCERT Exemplar]

Answer:
In the given figure, the tree line along the sea coast on an island near the equator shows that tree tops are permanently bent in one direction. The reason behind this movement of tree is that during the day time the wind blows from sea to land because land gets warmer more quickly than sea.

This makes the air of land, warm and lighter which is raised up in the sky. Therefore, the top of the bent trees shows the moving direction of wind from sea to land.

Question 2.
Describe an activity to demonstrate that warm air is lighter than cool air. [NCERT Exemplar]
Answer:
Take two paper bags of same size and hang them in the inverted position at the two ends of metal or wooden stick. Now, tie a piece of strong thread in the middle of the stick. Now, hold the stick by thread. The wooden stick with two paper bags tied to its two ends will hang like a common beam balance. Initially, the wooden stick is perfectly horizontal showing that the two paper bags contain an equal mass of the air.

Caution Perform the experiment with the help of a teacher.

Now, put the burning candle below the open mouth of one side paper bag. We will see that after sometime, the left side of wooden stick goes up showing that it has become lighter than the right side and the balance of the cup is disturbed. The reason for this is that when a burning candle is placed below the one side paper bag, the air above the candle flame gets heated. The hot air being lighter rises up and fills the paper bag above it. Therefore, this side of wooden stick becomes lighter and moves up.
This experiment shows that the air becomes lighter and moves up.

This fact of air is utilised in launching hot air balloons. In nature, there are several situations where warm air rises at a place. The air pressure at that place is lowered. The cold air from the surrounding areas rushes in to fill its place.

Question 3.
State the importance of air pressure. Give reasons for air pressure.
Answer:
The importance of air pressure can be discussed as follows:

It creates wind The difference in atmospheric pressure gives rise to the wind on the earth.
It influences weather Air movement, i.e. downward or upward movement of air, caused due to differences in pressure creates cloudy and clear sky, brings rain or fine weather.
Weather forecasting The changes in air pressure give important clues for weather forecasting. The air pressure is measured by an instrument called barometer.

Question 4.
A cyclone is generated from a thunderstorm. How a thunderstorm becomes a cyclone? Explain.
Answer:
When air moves gently (low speed), it is called a breeze while when it moves violently (high speed), it is called a storm. When the pressure of air drops, it indicates the possibility of a storm.

The swift movement of the falling water along with the rising warm air producing sound, lightning, heavy rain and strong wind is called thunderstorm. It develops in hot and humid tropical areas like India and is accompanied by heavy rains or hail. Thunderstorms are produced by the dark clouds which form at fairly low altitude in the atmosphere. In the tropical area, the air gets warmed up and makes it to rise, whereas humidity provides the water vapour for the formation of cloud.

Therefore, it can be said that to occur a thunderstorm, it requires moisture, rapidly rising warm air and sea breeze or mountains.

Question 5.
Advanced technology has helped people to save them from natural calamities like thunder storm and cyclone. Explain how.
Answer:
During the early part of the last century, the people residing in coastal regions have less than a day for the preparations or to evacuate their homes from an overcoming cyclone. But, the today’s situation is very different. Today we are much protected. We have satellites and radars which can issue the cyclone watch or cyclone alert before 48 hrs (in advance) of any expected storm and a cyclone warning is issued 24 hrs in advance.

Therefore, the coastal residents have sufficient time to prepare and evacuate their homes. The message related to cyclone is broadcasted over the ratio every hour or half hour when a cyclone is nearer the coast.

In this way, the advanced technology has helped us in giving better protection from cyclones. Several national and international organisations cooperate to monitor the cyclone related disasters.

Question 6.
The phenomenon of cloud formation, rain, storm and cyclone are inter linked. Do you agree? If yes, give a flow chart that explain this relation. [HOTS]
Answer:
Yes, the following flow chart explains the phenomenon leading to the formation of cloud, rain, stornrand cyclone.

Author Archives: Rohit

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