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CHAPTER – 10 Life in the Deserts | CLASS 7TH | NCERT GEOGRAPHY IMPORTANT QUESTIONS & MCQS | EDUGROWN

Chapter - 10 Life in the Deserts

MCQs

Question 1.
Which region is characterised by extremely high or low temperature and has scarce vegetation?
(a) Desert
(b) Fertile land
(c) Grassland
(d) None of these

Answer

Answer: (a) Desert

Question 2.
How many countries touch Sahara desert?
(a) Eleven
(b) Thirteen
(c) Sixteen
(d) Twenty

Answer

Answer: (a) Eleven

Question 3.
What was the maximum temperature recorded at Al-Azizia in south of Tripoli in Sahara desert in 1922?
(a) 48°C
(b) 48.7°C
(c) 57.7°C
(d) 39.7°C

Answer

Answer: (c) 57.7°C

Question 4.
The maximum temperature of Sahara during day time is about 50°C and at nights it is
(a) 0°C
(b) 10°C
(c) 30°C
(d) 40°C

Answer

Answer: (a) 0°C

Question 5.
Which of these trees is not found in Sahara desert?
(a) Mango
(b) Date palm
(c) Acacia
(d) All of these

Answer

Answer: (a) Mango

Question 6.
What is the energy product in great demand throughout the world?
(a) Uranium
(b) Fats
(c) Manganese
(d) Oil

Answer

Answer: (d) Oil

Question 7.
Which crop is famous in Egypt?
(a) Maize
(b) Wheat
(c) Cotton
(d) None of these

Answer

Answer: (c) Cotton

Question 8.
What are two words by which Ladakh is made of?
(a) La and Dak
(b) Lad and hakh
(c) Lad and akh
(d) None of these

Answer

Answer: (a) La and Dak

Question 9.
What is the capital of Ladakh?
(a) Jammu
(b) Srinagar
(c) New Delhi
(d) Leh

Answer

Answer: (d) Leh

Question 10.
What is the other name of Ladakh?
(a) Indus
(b) Kargil
(c) Khapa-chan
(d) Karakoram

Answer

Answer: (c) Khapa-chan

Question 11.
Which of the following birds are sighted in Ladakh?
(a) Robin
(b) Redstarts
(c) Raven
(d) All of these

Answer

Answer: (d) All of these

Question 12.
Hemis in the Ladakh is a famous
(a) monastery
(b) church
(c) temple
(d) mosque

Answer

Answer: (a) monastery

Match the contents of Column A with that of Column B:

Column AColumn B
1. Chiru(a) Buddhist religion
2. Willow tree(b) Depression with water in deserts
3. Drass(c) Coldest place
4. Gangri(d) Shahtoosh
5. Gompas(e) Cricket bat
6. Oasis(f) Glacier
Answer

Answer:

Column AColumn B
1. Chiru(d) Shahtoosh
2. Willow tree(e) Cricket bat
3. Drass(c) Coldest place
4. Gangri(f) Glacier
5. Gompas(a) Buddhist religion
6. Oasis(b) Depression with water in deserts

Fill in the blanks with appropriate words:

1. Sahara desert touches the boundaries of …………… countries.

Answer

Answer: eleven

2. The People of Sahara wear heavy robes as a protection against …………… and …………….

Answer

Answer: dust storms, hot winds

3. ………….. is enclosed by the Karakoram range in the north.

Answer

Answer: Ladakh

4. Yak’s milk is used to make ………….. and …………..

Answer

Answer: butter, cheese

5. Leh is connected to Kashmir through …………….. Pass.

Answer

Answer: Zoji la

6. ………….. is the most important river of Ladakh.

Answer

Answer: Indus

Question 1.
What does water actually mean to us?
Answer:

  • Water actually means life to plants, animals and people.
  • It is difficult for anyone to live in place,
  • Where there is no water to drink.
  • Where there is no grass for the cattle to feed on.
  • Where there is no water to help the crops to grow.

Question 2.
Discuss the places where extreme harsh temperatures are found.
Answer:

  • There are several places in the world where extreme harsh temperatures are found.
  • They are the places where temperature are as hot as fire.
  • On the other hand there are some as cold as ice.
  • These are the desert areas of the world.
  • They are characterised by low rainfall, scanty vegetation and extreme temperatures.
  • Based on temperatures they are:
  • Hot desert
  • Cold desert
  • People inhabit these lands wherever a little water is available to practise agriculture.

Question 3.
Define the term desert with example.
Answer:
It is an arid region with extreme temperatures and scarce vegetation. For example, Sahara and Ladakh.

The Hot Desert  – Sahara

Question 1.
Discuss the situation and location of Sahara Desert.
Answer:
Situation and Location of Sahara Desert:

  • Sahara desert covers large part of North Africa.
  • It is the largest desert of the world.
  • It has an area of around 85.4 lakh square kilometre.
  • It is almost 2.5 times larger than the total geographical area of India (32 lakh sq. km.)
  • The Sahara Desert covers eleven countries. They are Algeria, Chad, Egypt, Libya, Mali, Mauritania, Morocco, Niger, Sudan, Tunisia and Western Sahara.

Question 2.
Account for the relief of Sahara Desert.
Answer:
Relief of the Sahara Desert:

  • Sahara desert is a vast expanse of sand and sand.
  • But besides the vast stretches of sands, there are also gravel plains and elevated plateaus with bare rocky surface.
  • These rocky surfaces are more than 2500 metres high at some places.
  • Big boulders of stones and gravels are found all over the desert.

Climate

Question .1.
Give an account of the climate of Sahara Desert.
Answer:
Climate of Sahara Desert:

  • Climate of the Sahara desert is scorching hot and parch dry.
  • It has a short rainy season.
  • The sky is cloudless and clear.

Here moisture evaporates faster than it accumulates.

  • Days are unbelievably hot.
  • Temperatures during the day soars as high as 50°C, heating up the sand and bare rocks.
  • They in turn, radiate heat making everything hot all around.

Nights are freezing cold with temperatures nearing zero degree.

Question 2.
Which place in the Sahara desert recorded the highest temperature in 1922?
Answer:
Al Azizia in Sahara, south of Tripoli (Libya) recorded the highest temperature of 57.7°C in 1922.

Flora and Fauna

Question 1.
Explain the flora and fauna of Sahara desert.
Answer:
Flora and Fauna of Sahara Desert:

  • Vegetation in the Sahara desert comprises of cactus, date, palms and acacia.
  • In some places there are oasis-green islands with date palms surrounding them.
  • Camels, hyenas, jackals, foxes, scorpions, numerous varieties of snakes and lizards are the prominent animal species which inhabit the Sahara Desert.

People

Question 1.
Explain the life of people of Sahara Desert.
Answer:
Life of People of Sahara Desert:

  • The Sahara desert has a very harsh climate.
  • Despite this it has been inhabited by various groups of people.
  • They pursue different activities.

Among them are the Bedouins and Tuaregs.

  • These groups are nomadic tribes.
  • They rear livestock like goats, sheeps, camels and horses.
  • These animals provide them with milk, hides and hair.
  • They make leather belts, slippers, water bottles from hides.
  • They use hair in making mats, carpets, clothes and blankets.
  • They wear heavy robes as protection against dust-storms and hot winds.

Question 2.
Which areas in the Sahara supports settled life and how?
Answer:
The oasis in the Sahara and the Nile Valley in Egypt support settled population.

  • Since water is available people grow date palms.
  • Other crops like rice, wheat, barley and beans are grown.
  • Egyptian cotton is famous worldwide. It is grown in Egypt.

The discovery of oil in Algeria, Libya and Egypt is constantly transforming the Sahara desert.
Other minerals of the area are iron, phosphorus, manganese and uranium.

Question 3.
How is Sahara’s landscape gradually changing?
Answer:
The cultural landscape of the Sahara is undergoing change.

  • Gleaming glass cased office buildings, tower over mosques and superhighways criss-cross the ancient camel paths.
  • Trucks are replacing camels in salt trade.
  • Tuaregs are seen acting as guides to foreign tourists.
  • More and more Nomadic herdsmen are taking to city life finding jobs in oil and gas operations.

Question 4.
Describe an Oasis and its major features.
Answer:
An Oasis:

  • Depressions are formed when wind blows away the sands.
  • In the depressions where underground water reaches the surface, Oasis is formed.
  • Oasis is fertile.
  • People settle around these water bodies.
  • They grow date palms and other crops.
  • Sometimes the oasis is abnormally large.
  • Tafilalet Oasis in Morocco is a large oasis with an area of about 13000 sq. kms.

The Cold Desert – Ladakh

Question 1.
Explain the locational set up of the Ladakh Cold Desert.
Answer:
Locational set up of the Ladakh Cold Desert:

  • Ladakh is a cold desert.
  • It lies in the great Himalayas, on the eastern portion of Jammu and Kashmir.
  • The Karakoram Range in the north and the Zanskar Mountains in the south surround it.
  • Several rivers flow through Ladakh.
  • Indus is the main river.
  • The rivers form deep valleys and gorges.
  • Several glaciers are found in Ladakh.
  • Example: Gangri glacier

Question 2.
Discuss the climate of Ladakh.
Answer:
Climate of Ladakh:

  • Climate is extremely cold and dry.
  • The altitude in Ladakh varies from about 3000 metres in Kargil to more than 8000 metres in the Karakoram.
  • The air at great altitude is so thin that the heat of the sun is felt intensely.
  • The day temperatures in summers are just above zero degree and the night temperatures well below 30°C.
  • It is freezing cold in the winters when the temperatures remain below 40°C for most of the time.
  • Ladakh lies in the rain shadow of the Himalayas.
  • Hence there is little rainfall, as low as 10 centimetres every year.
  • The area experiences freezing winds and burning hot sunlight.
  • If people sit in the sun with their feet in the shade.
  • They suffer from both sunstroke and frost bite at the same time.

Flora and Fauna

Question 1.
What flora and fauna are found in Ladakh?
Answer:
Flora and Fauna found in Ladakh:

Due to dryness, vegetation is sparse.

  • There are very sparse patches of grasses and shrubs for animals to graze.
  • Groves of willows and poplars are found in the valleys.
  • During summers, fruit trees like apples, apricots and walnuts bloom.

Fauna of Ladakh includes birds and animals.

  • Several species of birds are sighted in Ladakh.
  • Robins, Redstarts, Tibetan Snowcock, Raven and Hoopoe are common.
  • Some of these are migratory birds.
  • The animals of Ladakh are the wild goats, wild sheep, yak and special kinds of dogs.
  • The animals provide milk, meat and hides.
  • The yak’s milk is used to make cheese and butter.
  • The hair of the sheep and goat is used to make woollen clothes.

The Chiru or the Tibetan antelope is an endangered species. It is hunted for its wool known as shahtoosh.

  • The wool is light in weight and extremely warm.

People

Question 1.
Which tribes inhabit Ladakh? Explain their ways of life.
Answer:
The People of Ladakh:

  • The people of Ladakh resemble the inhabitants of Tibet and Central Asia.
  • They are either Muslims or Buddhists.
  • In fact several Buddhist monasteries dot the Ladakhi Landscape with their traditional ‘gompas’.
  • Sopie famous monasteries are Hemis, Thiksey, Shey and Lamayuru.

Ways of Life:

  • In the summer season people are busy in cultivation of barley, potatoes, peas, beans and turnip.
  • In winter people keep themselves engaged in festivities and ceremonies.

The women are very hard working.

  • They work both in the house and fields.
  • They also manage small business and shops.
  • Leh is the capital of Ladakh.
  • It is well-connected both by road and air.
  • The National Highway LA connects Leh to Kashmir Valley through the Zoji la Pass.

Question 2.
Name the 4 passes which the Manali-Leh highway crosses.
Answer:

  • Manali-Leh Highway crosses four passes:
  • Rohtang la, Baralacha la, Lungalacha la and Tanglang la.
  • The highway opens only between July and September when snow is cleared
    from the road.

Question 3.
What is major activity in Ladakh?
Answer:

  • Tourism is a major activity.
  • Several tourists stream in here from within India and abroad.
  •  Visits to the gompas, treks to see the meadows and glaciers, witnessing ceremonies and festivities are important activities of the Ladakh  people.
  • Life of people has now undergone a change due to modernisation.
  • The people of Ladakh have over the centuries learnt to live in balance and harmony with nature.
  • Due to scarcity of resources like water and fuel, they are used with reverence and care.
  • Nothing is discarded or wasted.
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CHAPTER – 9 Life in the Temperate Grasslands | CLASS 7TH | NCERT GEOGRAPHY IMPORTANT QUESTIONS & MCQS | EDUGROWN

Chapter - 9 Life in the Temperate Grasslands

MCQs

 

Question 1.
Approximately how much area of earth is covered with grasslands?
(a) 40%
(b) 25%
(c) 10%
(d) 33%

Answer

Answer: (b) 25%

Question 2.
What are the Temperate Grasslands of North America called?
(a) Prairies
(b) Sahara
(c) Nile
(d) Tropical region

Answer

Answer: (a) Prairies

Question 3.
Which is the Latin word that means meadow?
(a) Priata
(b) Susu
(c) Both (a) and (b)
(d) None of these

Answer

Answer: (a) Priata

Question 4.
Which country does the river Mississippi drain?
(a) Africa
(b) USA
(c) Amazon
(d) Canada

Answer

Answer: (b) USA

Question 5.
Rocky mountains are bounded by which of the grasslands on their east?
(a) Pampos
(b) Prairies
(c) Velds
(d) Sheep

Answer

Answer: (b) Prairies

Question 6.
Due to the absence of the north-south barriers a local wind blows in USA which is called
(a) loo
(b) cool breeze
(c) chinook
(d) none of these

Answer

Answer: (c) chinook

Question 7.
How much lowest temperature has been recorded during winter in North America?
(a) 20°C
(b) -20°C
(c) 10°C
(d) -10°C

Answer

Answer: (b) -20°C

Question 8.
What are the cattle farms in North America called?
(a) Velds
(b) Arches
(c) Sheds
(d) Ranches

Answer

Answer: (d) Ranches

Question 9.
What is the second major industry of Canada?
(a) Dairy farming
(b) Coal mining
(c) Gold mining
(d) None of these

Answer

Answer: (a) Dairy farming

Question 10.
The important cities in American Prairies are
(a) Chicago
(b) Minneapolis
(c) Kansas
(d) All of these

Answer

Answer: (d) All of these

Question 11.
What lies to the west of veld grasslands?
(a) Drakensburg
(b) River Orange
(c) Kalahari desert
(d) Nothing

Answer

Answer: (c) Kalahari desert

Question 12.
Which is the coldest month in the Veld grasslands?
(a) January
(b) July
(c) June
(d) October

Answer

Answer: (b) July

Question 13.
Which of these animal is not found in the Velds?
(a) Leopard
(b) Cheetah
(c) Kudu
(d) Dodo

Answer

Answer: (d) Dodo

Question 14.
What is Kimberley famous for?
(a) Gold
(b) Diamonds
(c) Silver
(d) Platinum

Answer

Answer: (b) Diamonds

Match the contents of Column A with that of Column B

Column AColumn B
1. Veld(a) Tribes
2. Apache, cree(b) Local wind in prairies
3. Coyotes, gophers(c) Ranches
4. Chinook(d) Dutch people
5. Bison(e) Animals
Answer

Answer:

Column AColumn B
1. Veld(d) Dutch people
2. Apache, cree(a) Tribes
3. Coyotes, gophers(e) Animals
4. Chinook(b) Local wind in prairies
5. Bison(c) Ranches

Fill in the blanks with appropriate words:

1. Areas with little rainfall have short ……………

Answer

Answer: grasses

2. Velds are drained by the rivers …………. and ……………

Answer

Answer: orange, Limpopo

3. A machine called …………… can do the tasks of threshing, sowing and ploughing.

Answer

Answer: combine

4. Prairies have large mineral deposits of coal and ……………..

Answer

Answer: iron

Question 1.
Define forests and grasslands.
Answer:
Forests:
Forests are defined as the places where trees are the main type of vegetation.

Grasslands:
Grasslands are defined as regions where grasses form the dominant type of plant life.

Question 2.
Give the main features of Grasslands.
Answer:
Main Features of Grasslands:

  • Grasslands spread almost over 25% of the total land surface.
  • The type of plants that grow in grasslands greatly depend on the type of climate and the type of soil.
  • Climate plays an important role in the formation of grasslands.
  • Hence it is generally used as a basis to divide the World’s Grasslands.
  • They are classified into two broad categories:
  • Temperate Grasslands: They grow in the temperate regions.
  • Tropical Grasslands: They occur in the tropical regions.

Question 3.
Name various grasslands along with their areas.
Answer:
Various grasslands along with their areas are:
Tropical grasslands:

  • Savannah – East Africa
  • Campos – Brazil
  • Linos – Venezuela

Temperate grasslands:

  • Pampas – Argentina
  • Prairie – North America
  • Veld – South Africa
  • Steppe – Central Asia
  • Down – Australia.

The Prairies

Question 1.
Explain the main features of Prairie Grasslands.
Answer:
Major Features of Prairie Grasslands:
The temperate grasslands of North America are termed as Prairies.

  • It is region of flat, gently sloping or hilly land,
  • They are covered chiefly by grasses.

Prairies are treeless but, woodlands can be found near the low lying plains, flanked by river valleys.

  • Trees are few and far between.
  • They are actually a “sea of grass.”

Question 2.
Where are the Prairies situated? Which rivers drain them?
Answer:

  • The prairies are bound by the Rocky Mountains in West and the Great Lakes in the East.
  • They cover parts of United States of America and parts of Canada.
  • In the U.S.A., the area is drained by the tributaries of Mississippi.
  • The Canadian Prairies are drained by the tributaries of Saskatchewan Rivers.

Question 3.
Name the various tribes living in the prairies.
Answer:
Various tribes living in prairies—native Americans called ‘Red Indians’, and the other tribes like the Apache, the crow, the cree and the pawnee.

Climate

Question 1.
Describe the climate of Prairies.
Answer:
Climate of Prairies:

  • The prairies are located in the heart of North American Continent.
  • The climate is of continental type with extremities of temperatures.
  • Summers are warm with temperatures of around 20°C.
  • In winter temperatures of -20°C are recorded in Winnipeg, Canada. During this season thick blanket of snow covers the region.
  • The annual rainfall is moderate.
  • It is ideal for the growth of grass.
  • Due to the absence of the north-south barter, a local wind “chinook” blows here. It is hot and raises the temperature in winter in a short time.

Question 2.
What is “Chinook”?
Answer:
Chinook is a hot wind that blows in winter and raises the temperature within a short period of time.

  • This increase in temperature results in melting of snow.making pasture Jiand available for grazing.

Flora and Fauna

Question 1.
Give an account of flora and fauna of the Prairie Grasslands.
Answer:
Flora and Fauna of the Prairie Grasslands:

  • Prairies are practically treeless.
  • With the availability of winter, trees like willows, alders and poplars grow here and there.

Places that receive rainfall of over 50 cm. are suitable for farming due to fertile soil.

  • Major crop of this area is maize.
  • Potatoes, soyabean, cotton and alfa-alfa are also grown in this region.

Areas where rainfall is very less or unreliable, grasses are short and sparse.

  • These areas are suitable for cattle rearing.
  • Large cattle farms called ranches are looked after by sturdy men called cowboys.
  • Bison or the American buffalo is the most important animal of this region.
  • Bison nearly got extinct due to its indiscriminate hunting.
  • It is now a protected species.
  • The other animals found in this region include rabbits, coyotes, gophers and Prairie dogs.

People

Question 1.
Describe the life of the people in the Prairie Grasslands.
Answer:
Life of the people in the Prairie Grasslands:

  • People of the prairie grasslands are very hardworking.
  • They have successfully used technology to utilise their rich natural resources.
  • There are two most developed countries in the world.
  • They are USA and Canada.
  • Prairie region spreads in both the countries.
  • Scientific methods of cultivation and use of tractors, harvesters and combines have made North America a surplus food producer.
  • The prairies are also known as “Granaries of the World” due to the huge surplus of wheat production.
  • Dairy farming is another major industry.
  • The dairy belt extends from the Great Lakes region to the Atlantic coast in the east.
  • Dairy farming and extensive agriculture both promote setting up of food processing industries in this region. People are engaged in their activities in large numbers.
  • Large mineral deposits particularly coal and iron ore found in abundance here.
  • There is a good network of roads, railways and canals in this region.
  • Both these have made it the most industrialised region in the world.

Question 2.
Mention the important cities of the U.SA and Canada Prairies.
Answer:
Important cities in the U.S.A. are:

  • Chicago
  • Mineapolis
  • Indianapolis
  • Kansas
  • Denver

In Canadian Prairies the important cities are:

  • Edmonton
  • Saskatoon
  • Calgary
  • Winnipeg

Question 3.
Write the uses of machine ‘combine’.
Answer:
Combine is a single machine which can combine the tasks of sowing, ploughing and threshing.

The Velds

Question 1.
Explain the topography of the Velds Grasslands?
Answer:
Topography of the Velds Grasslands:

  • Velds are the temperate grasslands of South Africa.
  • They are rolling plateaus with varying heights between 600 m and 1100 m.
  • The region is bounded by the Drakensburg Mountains on the east, by the Kalahari desert on the west and by “high Velds” on the north-eastern part.
  • On the north-eastern part, the region attains a height of more than 1600 m in some places.
  • The countries that are covered by the Velds are:
  • Namibia, Botswana, South Africa, Sawaziland and Lesotho. –
  • The tributaries of River Orange and Limpopo drain the region.

Climate

Question 1.
Explain the climate of Velds Grasslands.
Answer:
Climate of Velds Grasslands:
The Velds lie under the influence of the Indian ocean. Hence their climate is mild.

Winters are cold and dry.

  • Temperatures vary between 5°C and 10°C.
  • July is the coldest month.
  • The rainfall is scanty in the winter months from June till August.
  • During the period drought may occur.

Summers are short and warm.

  • Johannesburg records about 20°C temperature in the summer.
  • The Velds receive rainfall mainly in the summer months from November to February.
  • This is mainly because of the warm rear currents that wash the shores of the Velds.

Flora and Fauna

Question 1.
Give an account of the flora and fauna found in the Velds Grasslands.
Answer:
Flora and Fauna Veld Grasslands:

  • In the Velds grasslands vegetation is sparse.
  • Grasses dominate the landscape.
  • Red grass grows in bush Velds.
  • In the high Velds acacia and maroola grow well.
  • The animals of the Velds are primarily lions, leopards, cheetah and kudu.

People

Question 1.
Describe the life of the people inhabiting the Velds Grasslands.
Answer:
Life of People inhabiting the Velds Grasslands:

  • In the Velds, people are engaged in cattle rearing and mining.
  • The soils are not very fertile in the Velds due to the presence of discontinuous grasses exposing barren surface.

In the areas where land is fertile, crops are grown.

  • Main crops of the region are maize, wheat, barley, oats and potatoes.
  • Cash crops like tobacco, sugarcane and cotton are also grown.

Sheep rearing is the most important occupation of the people.

  • Sheep is bred mainly for wool.
  • Easy availability of wool has given rise to the woollen industry in the Velds.
  • Merino sheep is a popular species.

Dairy farming is the other important occupation of the people.

  • Cattle are reared in the warmer and wetter regions.
  • Major dairy products like butter, cheese are produced for both domestic supply and also for export.

Question 2.
Describe mining as another occupation of the people of Veld region.
Answer:
Mining is yet another important occupation of the people.

  • The Velds have rich reserve of minerals.
  • Iron and steel industry has developed where coal and iron are mined.

Gold and diamond mining are major occupations of the people of this region.

  • Johannesburg is known for being the Gold Capital of the world.
  • Kimberley is famous for its diamond mines.

Mining of diamond and gold in South Africa led to the establishment of trade ties with Britain.

  • South Africa gradually became a British Colony.
  • This mineral rich area has a well-developed network of transport and communication.
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CHAPTER –  8 Human Environment Interactions: The Tropical and the Subtropical Region | CLASS 7TH | NCERT GEOGRAPHY IMPORTANT QUESTIONS & MCQS | EDUGROWN

Chapter - 8 Human Environment Interactions: The Tropical and the Subtropical Region

MCQs

Question 1.
What are the common needs of all the people?
(a) Food
(b) Toys
(c) Camera
(d) All of these

Answer

Answer: (a) Food

Question 2.
The place where a river flows into another water body is called
(a) river’s mouth
(b) river’s nose
(c) river’s leg
(d) all of these

Answer

Answer: (a) river’s mouth

Question 3.
How is the climate of Amazon basin characterized?
(a) By cold and wet
(b) By hot and wet
(c) By dry or wet
(d) None of these

Answer

Answer: (b) By hot and wet

Question 4.
At night the temperature goes down in the Amazon basin but the humidity
(a) remains same
(b) remains low
(c) remains high
(d) none of these

Answer

Answer: (c) remains high

Question 5.
The forests are in fact so thick that the dense ‘roof is created by
(a) cement
(b) concrete
(c) leaves
(d) stones

Answer

Answer: (c) leaves

Question 6.
Toucans are the type of
(a) animals
(b) crops
(c) birds
(d) reptiles

Answer

Answer: (c) birds

Question 7.
Manioc food belongs to the area of
(a) South America
(b) South Africa
(c) Amazon area
(d) Ganga basin

Answer

Answer: (a) South America

Question 8.
Where is one horned rhinoceros found?
(a) Brahmaputra plain
(b) Amazon basin
(c) Ghaghra plain
(d) None of these

Answer

Answer: (a) Brahmaputra plain

Question 9.
What is the main occupation of the people living in Ganga-Brahmaputra basin?
(a) Fishing
(b) Lumbering
(c) Mining
(d) Agriculture

Answer

Answer: (d) Agriculture

Question 10.
Where is Bengal Tiger found?
(a) Mountain area
(b) Amazon basin
(c) Sundarbans delta
(d) All of these

Answer

Answer: (c) Sundarbans delta

Question 11.
On which river bank are Allahabad, Kanpur, Varanasi, located?
(a) River Ganga
(b) River Brahmaputra
(c) River Hooghly
(d) River Yamuna

Answer

Answer: (a) River Ganga

Match the contents of Column A with that of Column B:

Column AColumn B
1. Susu(a) Variety of snakes
2. Kolkata(b) Important port
3. Cassava(c) Stored water in leaves
4. Bromeliads(d) Blind dolphin
5. Anaconda and boa(e) Underground root
Answer

Answer:

Column AColumn B
1. Susu(d) Blind dolphin
2. Kolkata(b) Important port
3. Cassava(e) Underground root
4. Bromeliads(c) Stored water in leaves
5. Anaconda and boa(a) Variety of snakes

Fill in the blanks with appropriate words:

1. Women of warrior tribe in Roman empire were called ……………

Answer

Answer: Amazons

2. Small rivers that join a main river are called …………..

Answer

Answer: tributaries

3. Large houses called …………. have steep slanting roof.

Answer

Answer: maloca

4. West Bengal and Assam are known for ………… plantations.

Answer

Answer: tea

5. People in …………… eat queen ants and their eggs.

Answer

Answer: Amazon basin

Question 1.
Why is Renuka excited?
Answer:
Renuka is excited as her wildlife photographer uncle was coming back home. He had introduced her to the books having pictures of distant lands and life of people there.

Question 2.
What are the similarities or differences between the people of different countries?
Answer:
People of deserts, frozen land or hot wet forests only look different, they have same basic needs of food clothing and shelter. The children are all alike,they play same games, sing, dance, fight or make up.
The main difference is that some of them live close to nature and have learnt to use and protect nature.

Life in the Amazon Basin

Question 1.
Describe the situation and location of the Amazon Basin.
Answer:
Situation and Location of the Amazon Basin:

  • Look at the world map (on page 56 of the textbook), the Amazon Basin lies very close to the equator, between 10°N to 10°S.
  • This region is known as the equatorial region.
  • The river Amazon flows through this region.

It flows1 from the mountains in the west and reaches the Atlantic Ocean in the east.

  • Numerous tributaries join in the Amazon river and they together form the Amazon Basin.
  • The river basin drains portions of Brazil, parts of Peru, Bolivia, Ecuador, Columbia and a small part of Venezuela.

Question 2.
Name the countries of the basin through which the equator passes.
The countries of the basin through which the equator passes are
South America:

  • Ecuador
  • Columbia
  • Brazil

Africa:

  • Yabon
  • Dem.Rep of Congo
  • Uganda
  • Kenya

Asia:

  • Indonesia

Question 3.
What is river’s mouth?
Answer:
The place where a river flows into another body of water is called the river’s mouth.

Question 4.
Define the tributary.
Answer:
The small rivers that join the main river are called its tributaries, for example Son, Yamuna are tributaries of Ganga.

Climate

Question 1.
Give an account of the climate of Amazon Basin.
Answer:
Climate of Amazon Basin:

  • Amazon basin stretches directly on the Equator.
  • It has hot and wet climate throughout the year.
  • Both day and nights are almost equally hot and humid.
  • Skin feels sticky.
  • It rains almost every day.
  • It rains without much warning.
  • The day temperatures are high with high humidity.
  • At night the temperature goes down but humidity is high.

Rainforests

Question 1.
Give an account of rain forests and wild life of Amazon Basin.
Answer:
Rainforests of Amazon Basin:

  • In Amazon basin, it rains heavily.
  • Thick forests grow here.

They are in fact so thick and dense that “roof* created by leaves and branches do not allow the sunlight to reach the ground.

  • The ground remains dark and damp.
  • Only shade tolerant vegetation grows here.
  • Orchids, bromeliads grow as plant parasites.

Wild Life of Amazon Basin

  • The rainforests are rich in fauna.
  • Birds like toucans, humming birds, birds of paradise with their brilliantly coloured plumage, oversized bills for eating make them different from birds found in India.
  • These birds also make loud sound in the forests.
  • Animals like monkeys, sloth and ant-eating tapirs are found here.
  • Various species of reptiles and snakes are also found in these jungles.
  • Crocodiles, snakes, pythons abound.
  • Anaconda and Boa constrictor are some of the species.
  • Amazon basin is also the home of thousands of species of insects.
  • Several species of fish like the flesh-eating Piranha fish is also found in the river.
  • Amazon basin is actually extraordinarily rich in the variety of life found there.

People of the rainforests

Question 1.
Describe the life of people of the Rainforests of Amazon”Basin.
Answer:
Life of the People of the Rainforests of Amazon Basin:
People grow most of their food in small areas after clearing some trees in the forest.

  • Men hunt and catch fish along the rivers.
  • Women take care of the crops.
  • They mainly grow tapioca, pineapple, and sweet potato.
  • Hunting and fishing being uncertain, it is the women who keep their families alive by feeding them the vegetables they grow.
  • They practise “slash and bum agriculture”.
  • The staple food is manioc. It is also known as cassava. It grows under the ground like the potato.
  • The people also eat queen ants and egg sacs.
  • Cash crops like coffee, maize and cocoa are also grown in the Amazon Basin.

The rainforests provide a lot of wood for the houses.

  • Some families live in thatched houses. They are shaped like beehives.
  • There are other large apartment-like houses called “Maloca”. They have steeply slanting roofs to allow rain water flowing down easily.

Question 2.
What changes have occurred with life of the people of Amazon Basin in recent times?
Answer:
Life of the people of the Amazon basin is slowly changing.
In the early days, to reach the heart of the forest, river was the only means of transport.

  • In modem times means of transport have developed considerably. In 1970 the Trans Amazon highway made all parts of the rainforest accessible.
  •  Aircrafts and helicopters are also used for reaching various places.
  • The aborigines (indigenous) population was pushed out.
  • Diverse rain forests are being destroyed with long term consequences.

Question 3.
What is the affect of Developmental activities in the Amazon basin?
Answer:
The developmental activities are leading to the gradual destruction of the biologically diverse rainforests. Annually a large area is disappearing. The top soil is being washed away and the land is becoming barren.

Question 4.
Give an account of Slash and Burn Agriculture.
Answer:
Slash and Bum Agriculture:

  • It is a way of cultivating land where farmers clear a piece of land by slashing or cutting down trees and bushes.
  • These are then burnt, which release the nutrients into soil.
  • New crops are grown in this cleared field for a few years.

After repeatedly using the patch of land, the soil loses its nutrients.

  • So it is abandoned.
  • Then they clear another plot of land to plant.

In the meantime young trees grow in the old field.

  • In this way soil fertility is restarted (restored).
  • People then return to it.
  • They start cultivating again by repeating the process.

Life in the Ganga-Brahmaputra Basin

Question 1.
Explain the physiography of the Ganga-Brahmaputra Basin.
Answer:
Physiography of the Ganga-Brahmaputra Basin:
The tributaries of river Ganga and Brahmaputra together form the Ganga- Brahmaputra basin in the Indian subcontinent.

  • It lies in the sub-tropical region.
  • It is located between 10°N and 30°N latitudes.

The tributaries of the River Ganga like the Ghagra, the Son, the Chambal, the Gandak, the Kosi and the tributaries of Brahmaputra drain it.

Human Environment Interactions The Tropical and the Subtropical Region Class 7 Extra Questions Geography Chapter 8 - 3

  • Some of the tributaries of the river Brahmaputra are:
  • Dihang, Dibang. Lohit and Dhansiri.

The main physiographical features of the Ganga-Brahmaputra Basin are:

  • Mountains and foothills of the Himalayas
  • Sundarbans delta
  • Ox-bow lakes dot the plain area.

Question 2.
River Brahmaputra is known. by different names in different places. It is called Tsangpo in Tibet. Find the other names of the river.
Answer:
Dehang, Dahang, Jarnuna, Meghna, Padma etc.

Question 3.
What is the climate of Ganga-Brahmaputra Basin?
Answer:

  • The Ganga-Brahamputra Basin is dominated by monsoon climate.
  • The monsoon brings rains from mid-June to mid-September.
  • The summers are hot.
  • The winters are cool and generally dry.

Question 4.
Look at the Map of’ India. List the states in which the Ganga-Brahmaputra Basin lies.
Answer:
Ganga:

  • Uttarakhand
  • Uttar Pradesh
  • Northern Madhya Pradesh
  • Northern Chhattisgarh
  • Bihar
  • Jharkhand
  • West-Bengai.

Brahmaputra:

  • Arunachal Pradesh
  • Assam
  • Meghalaya

Question 5.
How does environment play a dominant role in the distribution of population in the Ganga-Brahmaputra basin?
Answer:
Ganga-Brahmaputra Basin:

  • Ganga-Brahmaputra basin has varied topography.
  • The environment plays a dominant role in the distribution of the population here.
  • The mountain areas with steep slopes have inhospitable terrain.
    Hence less number of people live in the mountain area of the Ganga-Brahmaputra basin.
  • The plain area provides the most suitable land for human habitation.
  • The soil is fertile.
  • Agriculture is the main occupation of the people.
  • The density of population is very high.
  • Since cultivation of paddy requires sufficient water, it is grown in the areas where the amount of rainfall is high or enough water is available.

Question 6.
Give an account of agriculture in the Ganga-Brahmaputra Basin.
Answer:
Agriculture in Ganga-Brahmaputra Basin:

  • Wheat, Maize, Sorghum, Gram and Millets are major crops that are grown as food crops.
  • Cash crops like sugarcane and jute are grown in large quantities.
  • Banana plantation are seen in some areas of the plain.

Human Environment Interactions The Tropical and the Subtropical Region Class 7 Extra Questions Geography Chapter 8 - 2

  • In West-Bengal and Assam tea is grown in plantations.
  • Silk is produced through the cultivation of silk worms in parts of Bihar and Assam.
  • In the mountains and hills, crops are grown on terraces made on gentle slope.

Question 7.
Explain the forest wealth of Ganga-Brahmaputra Basin.
Answer:

  • The vegetation cover is according to the type of landforms.
  • Delta region is covered with mangrove forests.
  • In this basin tropical deciduous trees grow along with teak, sal, peepal.
  • Thick bamboo groves are in Brahmaputra plains.
  • In parts of Uttarakhand, Sikkim and Arunachal Pradesh and other small states of the North-east coniferous trees like pine, deodar, and fir are seen.

Question 8.
Write about the fauna of Ganga-Brahmaputra basin.
Answer:
A wide variety of wild life is found here:

  • Elephants, tigers, deer and monkeys are common.
  • One homed rhinoceros, Bengal tiger, crocodiles and alligators are found.
  • Large aquatic life is found in fresh waters like rohu, catla, hilsa.

Question 9.
Why are terraces built on the mountain slopes?
Answer:
Terraces are built on the gentle (mountain) slopes to create flat surfaces on which crops are grown. The slope is removed so that water does not ran off rapidly.

Question 10.
Where is blind variety of dolphin found?
Answer:
In the fresh water of River Ganga and River Brahmaputra, blind variety of dolphin, locally called Susu, is found.

Question 11.
Why is blind dolphin facing extinction?
Answer:
The blind dolphin or Susu is facing extinction at the hand of humans.

  • The Dolphin eats small fish only. The presence of Susu is an indication of the health of the river.
  • The untreated industrial and urban wastes with high amounts of chemical are killing this species.

Question 12.
Which towns and cities are located in the Ganga-Brahmaputra Basin?
Answer:

  • The Ganga-Brahmaputra Plain has several big towns and cities.
  • The cities of Allahabad, Kanpur, Varanasi, Lucknow, Patna all with a population of more than ten lakhs are located along the River Ganga.
  • The waste water from these towns and industries is discharged into the river leading to its pollution.

Question 13.
Write a note on the transportation found in the Ganga-Brahmaputra Basin.
Answer:

  • All the four means of transport are well-developed in Ganga-Brahmaputra basin.
  • In the plain areas the roadways and railways transport the people from one place to another.
  • The waterways, is an effective means of transport particularly along the rivers. Kolkata is an important port on the river Hooghly.
  • The plain areas have a large number of airports.

Question 14.
Explain:
tourism is an important activity of the Ganga-Brahmaputra basin.
Answer:
Tourism is an important activity of the basin.

The following make the basin important from the point of tourism.

  • Taj Mahal on the banks of River Yamuna in Agra.
  • Allahabad on the confluence of the River Ganga, Saraswati and Yamuna.
  • Buddhist centres in Uttar Pradesh and Bihar. ,
  • Lucknow with its Imambara.
  • Assam with Kaziranga and Manas wild life sanctuaries.
  • Arunachal Pradesh with a distinct tribal culture.

There are so many other places to visit.

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Rohit0 comments

CHAPTER –  7 Geography Human Environment: Settlement, Transport and Communication | CLASS 7TH | NCERT GEOGRAPHY IMPORTANT QUESTIONS & MCQS | EDUGROWN

MCQs

Question 1.
Where did early man live?
(a) On trees and in caves
(b) In kuchcha houses
(c) In pucca houses
(d) In huts

Answer

Answer: (a) On trees and in caves

Question 2.
Which type of settlement is occupied for a short time?
(a) Permanent settlements
(b) Temporary settlements
(c) Both (a) and (b)
(d) None of these

Answer

Answer: (b) Temporary settlements

Question 3.
The natural conditions for selection of an ideal site are
(a) favourite climate
(b) availability of water
(c) suitable land
(d) all of these

Answer

Answer: (d) all of these

Question 4.
In which environment do people build slanting roofs of their houses?
(a) Heavy rainfall
(b) Bright sun light
(c) Heavy cold
(d) None of these

Answer

Answer: (a) Heavy rainfall

Question 5.
In which of the following settlements are the people engaged in activities like fishing, agriculture, craftswork etc.?
(a) Rural settlements
(b) Urban settlements
(c) Forestry settlements
(d) None of these

Answer

Answer: (a) Rural settlements

Question 6.
Why do people move from one place to other?
(a) For jobs
(b) For better education
(c) For medical facilities
(d) All of these

Answer

Answer: (d) All of these

Question 7.
Roads built underground are called
(a) subways
(b) expressways
(c) airways
(d) flyovers

Answer

Answer: (a) subways

Question 8.
Which country has the largest railway network in Asia?
(a) China
(b) India
(c) Pakistan
(d) Japan

Answer

Answer: (b) India

Question 9.
Name the mode of transport used to reach an island.
(a) Train
(b) Ship
(c) Car
(d) Bus

Answer

Answer: (b) Ship

Question 10.
Which is the best means to transport to reach inaccessible areas?
(a) Airways
(b) Waterways
(c) Railways
(d) Roadways

Answer

Answer: (a) Airways

Question 11.
Which one of the following is NOT a means of communication?
(a) Table
(b) Mobile phone
(c) Newspaper
(d) Magazine

Answer

Answer: (a) Table

Match the contents of Column A with that of Column B:

Column AColumn B
1. Manali-Leh(a) Manufacturing, trading, services
2. Waterways(b) Highest rail route
3. Xining to Lhasa(c) Agriculture, fishing, forestry
4. Urban areas(d) Highest roadways
5. Rural areas(e) Cheapest mode of transport
Answer

Answer:

Column AColumn B
1. Manali-Leh(d) Highest roadways
2. Waterways(e) Cheapest mode of transport
3. Xining to Lhasa(b) Highest rail route
4. Urban areas(a) Manufacturing, trading, services
5. Rural areas(c) Agriculture, fishing, forestry

Fill in the blanks with appropriate words:

1. People of deserts or deep forests live in ………… settlements.

Answer

Answer: temporary

2. In regions of heavy rainfall houses have …………. roofs.

Answer

Answer: slanting

3. …………. are built over raised structures.

Answer

Answer: Flyovers

Question 1.
How did early human beings depend entirely on nature?
Answer:
Early human beings depended entirely on nature for food, clothing and shelter.

Question 2.
What new skills did the human beings learn in course of time?
answer:
In course of time human beings learnt new skills, like:

  • to grow food, use fire, use wheel.
  • to build homes, and
  • to develop better means of transport and communication.

In this way human beings modified the environment where they lived.

Question 3.
What are settlements? How (when/why) did human beings start to have permanent settlements?
Answer:

  • Settlements are places where people build their homes and live there.
  • Early human beings lived on trees and in caves.
  • When they started to grow crops it became necessary to have a permanent home.

Question 4.
How have the settlements changed over a period of time?
Answer:
Settlements are places where people build homes and live. They have changed over a period of time due to many other changes:

  • Early man lived in caves and under trees and with the beginning of agriculture more permanent settlements were developed.
  • The settlements grew near the river valleys due to availability of water and fertile soil.
  • With the growth of trade and industries these settlements became larger leading to development of civilization.
  • With the growth in technology these settlements further grew.

Question 5.
Do you recall the names of civilizations that grew along the banks of rivers Indus, Tigris, Nile and Hwang-Ho?
Answer:

  • Indus – Indus valley civilisation
  • Tigris – Mesopotamia civilisation
  • Nile – Egyptian civilisation
  • Hwang-Ho – Chinese civilisation

Question 6.
What is a site? Which factors help to select a site for settlement?
Answer:
The place where a building or a settlement is developed is called a site.
The factors for selecting a site for settlement are:

  • Favourable climate.
  • Availability of water, electricity.
  • Land for cultivation and construction.
  • Fertile soil.
  • Availability of other resources.

Question 7.
What are the two types of settlements on the basis of period for which they are occupied? Give some features of temporary settlements.
Answer:
Settlements are of two types on the basis of period of their occupation. They are :

  • Permanent
  • Temporary.

Features of Temporary Settlements:
Settlements which are occupied for a short time are called temporary settlements.

  • The people who live in deep forests, hot and cold deserts, and mountains often reside in temporary settlements.
  • They practise hunting, gathering, shifting cultivation and transhumance.

Question 8.
Explain major features of permanent settlements.
Answer:
Features of Permanent Settlements:

  • More and more settlements today are permanent settlements.
  • In these settlements, people build homes to live in permanently.
  • These settlements are generally found in the plains, on the uplands or near the water bodies.
  • People have agriculture and industries as their major occupations.
  • People also have engaged themselves in tertiary and quaternary activities.
  • Houses in these settlements are built of bricks, concrete, cement and steel.
  • The houses are also generally multistoreyed.

Question 9.
Define the term transhumance.
Answer:
Transhumance is the seasonal movement of people specially nomads, who shift along with their herd in search of a place according to change in climate.

Question 10.
Why was Gurpreet late for Mary’s birthday party?
Answer:
Gurpreet came late that too coughing and wheezing due to heavy traffic and related pollution.

Question 11.
What is the reason behind increased urban population?
Answer:
People come looking for jobs, better education and medical facilities.

Question 12.
How does rise in population affect the city?
Answer:
Rise in population in cities due to availability of facilities is creating problems also:

  • This leads to increase in number of vehicles and therefore traffic jams.
  • Increase in slum dwelling and squatter settlements and unhygienic conditions.
  • Shortage of water, power and other resources.
  • Pollution because of vehicles and excess of garbage.

Question 13.
What is situation of villages in comparison with cities?
Answer:
Villages do not have big cinema houses or well equipped schools and hospitals. But, they have open spaces, fresh air to breathe.

Question 14.
What are different types of settlements?
Answer:
Settlements are of the following types:

  1. Rural settlements
  2. Urban settlements
  • The villages are Rural Settlements.
  • In these settlements people are engaged in agriculture, fishing, forestry, crafts work and trading etc.

Rural settlements are of two types:

  1. Compact and
  2. Scattered.
  • A Compact settlement is a closely built area of dwellings. They are built on flat land.
  • In a scattered settlement dwellings are spaced over an extensive area. These settlements are mostly found in hilly tracts, thick forests, and regions of extreme climate.
  • In rural areas, people build houses to suit their environment.
  • In regions of heavy rainfall, they have slanting roofs.
  • In the places where water accumulates in the rainy season, the houses are constructed on a raised platform or stilts.
  • Thick mud walled houses with thatched roots are very common in areas of hot climate.
  • Local materials like stones, mud, clay, straw etc. are used to construct , houses.
  • The towns are small urban settlements and the cities are larger urban settlements.

Transport

Question 1.
What is transport? Give a brief history of transport development.
Answer:

  • Transport is the means by which people and goods move.
  • In the early days it took a great deal of time to travel long distances.
  • People had to walk and used animals to carry their goods.
  • Invention of the wheel made transport easier.

With the passage of time, different means of transport developed but even today people use animals for transport.

  • In our country, donkeys, mules, bullocks and camels are common.
  • In the Andes Mountains of South America, llamas are used.
  • Yaks are used in Tibet.
  • The early traders from other countries used to take several months to reach India.
  • They took either the sea route or the land route.
  • Aeroplanes have made travel faster.
  • Now it takes only 6-8 hours to travel from India to Europe.
  • Modern means of transport thus saves time and energy.

Question 2.
Name the means of transport.
Answer:
Four Means of Transport:

  • Roadways
  • Railways
  • Waterways
  • Airways

Roadways

Question 1.
Describe roadways as a means of transport.
Answer:
Roadways as a Means of Transport:

  • The most commonly used means of transport, especially for short distances, are roads.
  • They are of two types:
  • Metalled (Pucca) and
  • Unmetalled (Kuchcha)
  • The plains have a dense network of roads.
  • Roads have also been built in deserts, forests and even high mountains.
  • Manali-Leh highway in the Himalayan-mountains is one of the highest roadways in the world.
  • Roads built underground are called subways/under passes or paths.
  • Flyovers, are built over reused structures.

Question 2.
Can you tell why there are more roads in the plains than in the hills?
Answer:
Yes, because of the following reasons:

  • Less costly.
  • Less time consuming
  • Less needs for building bridges and culverts
  • Dense population requires more road transport
  • Agriculture and industries need roads urgently
  • Movements of goods and traffic is the need of the plains.

Question 3.
What are expressways? Give example.
Answer:
6-8 lane highways for fast moving traffic are called expressways e.g., Noida expressway.

Railways

Question 1.
Account for Railways as a means of land transport.
Answer:
Railways as a means of land transport:

  • The railways carry heavy goods and people over long distanced quickly and cheaply.
  • The invention of steam engine and the Industrial Revolution helped in speedy development of rail transport.
  • Diesel and electric engines have largely replaced the steam engines.
  • In several places superfast trains have been introduced to make the journey faster.
  • Railway network is well-developed in the plains.
  • Advanced technological skills have enabled laying of railway lines in difficult mountain terrains also. But they are much fewer in number.
  • Indian railway network is well-developed with improvement on stations, internet booking information etc.
  • It is the largest in Asia.

Waterways

Question 1.
Describe inland waterways as a means of transport.
Answer:
Inland Waterways:
In early days waterways were used for transportation.

  • Waterways are the cheapest for carrying heavy and bulky goods over long distances.
  • They are mainly of two types:
  • Inland waterways, and
  • Sea routes.
  • Navigable rivers and lakes are used as inland waterways.

Some of the important inland waterways are:

  • Ganga-Brahmaputra river system.
  • Great Lakes in North America.
  • River Nile in Africa.

Question 2.
Write nugor features of Sea Routes.
Answer:
Major features of Sea Routes:
Sea and oceanic routes are mostly used for transporting merchandise and goods from one country to another.

  •  The terminal points are on these ports.
  •  Some of the important ports of the world are:
  • Singapore and Mumbai in Asia.
  • New York, Los Angeles in North America.
  • Rio-de-Janerio in South America.
  • Durban and Cape Town in Africa.
  • Sydney in Australia.
  • London and Rotterdam in Europe.

Name of some more Ports of the World are:

  • New Orleans; Philadelphia, Boston, Miami
  • Hawana, Sao Paulo, Buenos Aires, Lima.
  • Kolkata, Colombo.
  • Manila, Shanghai.
  • Perth, Darwin.

Airways

Question 1.
Give an account of Airways as a means of transport.
Answer:
Airways as a means of transport:

  • Air transport is the fastest means of transport.
  • It was developed in the early twentieth century.
  • It is also the most expensive due to high cost of fuels.
  • Air traffic is adversely affected by bad weather like fog and storms.
  • It is the only mode of transport to reach the most remote and distant areas especially where there are no roads and railways.
  • Helicopters are extremely useful in most inaccessible areas.
  • In times of calamities they are extensively used for rescuing people and distributing relief supplies like food, water, clothes and medicines.
  • Some of the important airports of the world are Delhi, Mumbai, New York, London, Paris, Frankfurt, Singapore and Hongkong.

Names of a few more airports are:

  • Chennai, Kolkata, Hyderabad, Guwahati, Amritsar, Ahmedabad.
  • Tokyo, Osaka.
  • Singapore, Jakarta, Kualalumpur, Porth, Sydney, Yangoon, Bangkok.
  • Hongkong, Beijing.
  • Colombo.

Communication

Question 1.
Write a note on Communication.
Answer:
Communication:

  • Communication is the process of conveying messages to others.
  • With the development of technology, humans have devised new and fast modes of communication.

Different modes of communication are used

  • to provide information.
  • to educate
  • to entertain

Through Newspapers, Radio, and Television we communicate with a large number of people.
These are therefore called mass media.

Satellites have made communication very fast.

  • Satellites have helped in
  • Oil exploration
  • Survey of forest
  • Underground water
  • Mineral wealth
  • Weather forecast and
  • Disaster warning.
  • Electronic mails or e-mails through Internet have become popular these days.
  • Wireless telephonic communications through cellular phones have also become very popular today.
  • Internet not only provides us with worldwide information and interaction but also makes our lives more comfortable.
  • Now we reserve tickets for railways, airways and even cinemas and hotels sitting at home.
  • With this kind of inter-connectivity—people to people, people to services and institutions—across the world, we
    are becoming a large global society.
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mekhalaschool0 comments

CLASS 6TH | UNIT 4: GEOMETRY | POLYGONS| REVISION NOTES

The word polygon takes its origin from the Greek, poly, meaning many and gon, meaning angle. Polygons are 2 dimensional closed shapes made up of straight lines. Sometimes the interior of a polygon is known as its body.

We see polygons all around us. The school building is having a square or rectangular walls. You may come across some houses with triangular roofs. The tiles laid on the floor may be in square or hexagonal shape. 

In this chapter, you will learn about polygons and their classifications.

Polygon: It is a closed figure bounded by straight line segments.

Some important facts about polygon:

  • Line segments forming a polygon are called sides of the polygon.
  • The point where two sides of a polygon meet are called the vertex of the polygon.
  • The line segment containing two non-adjacent vertices is called the diagonal of the polygon.
  • The angle formed at the vertices inside the closed figure are called interior angles.

Classification of polygons:

Polygons are classified according to the number of sides or vertices they have in to:

  • Traingle
  • Quadrilateral
  • Pentagon
  • Hexagon
  • Heptagon
  • Octagon
  • Nonagon
  • Decagon 

The figure below on the right side shows these polygons.

CONCAVE & CONVEX POLYGONS:
We know that each side of a polygon is connected by two consecutive vertices of the polygon.
A diagonal is a line segment that connects the non-consecutive vertices of a polygon. 
If a diagonal lies outside a polygon, then the polygon is called a concave polygon.
If all the diagonals lie inside the polygon, then the polygon is said to be a convex polygon.

A polygon with all its sides equal and all its interior angles equal is said to be a regular polygon. In this chapter, you will learn about regular polygons.

REGULAR & IRREGULAR POLYGONS:

A regular polygon is equiangular and equilateral. The word equiangular means, the interior angles of the polygon are equal to one another. The word equilateral means, the lengths of the sides are equal to one another.
The polygon with unequal sides and unequal angles is called an irregular polygon.

ANGLE SUM PROPERTY:
The sum of all interior angles of a polygon is called the angle sum.
.           
At one vertex, we extend a side. This side makes an angle with its consecutive side. This angle is called the exterior angle. The interior angle and the exterior angles are adjacent angles.  These angles form a linear pair. Hence the sum of the exterior angles of any polygon is 360°.

Let us consider some examples:

Example 1:

Find the sum of all the interior angles of a polygon having 29 sides.

Solution:

We know that sum of all the interior angle in a polygon = (n – 2) × 180°.

Here, n = 29.

Therefore, the sum of all interior angles = (29 – 2) × 180°.

                                                                = 27 × 180°.

                                                                = 4860°.

Example 2: Is it possible to have a polygon, the sum of whose interior angle is 9 right angles?

Solution:

Let the number of sides be n.

The sum of all interior angles = (2n – 4) × 90°.

So, (2n – 4) × 90° = 9 × 90°.

n = 6.5, hence it is not possible to have a polygon the sum of whose interior angles is 9 right angles.

Example 3: The sides of a Pentagon are produced in order. If the measure of exterior angles so obtained are x°,2 x°,3 x°,4 x°,5 x° and so on, find all exterior angles

Solution:

The sum of exterior angles = 360°.

So, x° + 2x° + 3x° + 4x° + 5x° = 360°.

15x° = 360°.

x° = 24°.

Hence, the exterior angles are 24°,  48°,  72°,  96°, and  120°.

Example 4: If each interior angle of a regular polygon is 144°, Find the number of sides in it.

Solution:

Let the number of sides be n.

Each interior angle = ((2n – 4) × 90°) / n.

144 = 180n – 360°.

n = 10.

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CLASS 6TH | UNIT 4: GEOMETRY | QUADRILATERAL | REVISION NOTES

The word quadrilateral is the combination of two Latin words quadri, meaning four, and latus, meaning side. You come across quadrilaterals every day. For example, the page of a book, the top of a pencil box, the top of a dining table and so on, are all quadrilaterals (rectangular shape). 

A simple closed figure formed by joining four line segments is called a quadrilateral.  It has four sides, four angles, four vertices and two diagonals.

In this chapter, you will learn about basic properties of a quadrilateral.

In a quadrilateral ABCD :

  • The four points A, B, C, D are called its vertices.
  • The four line segments AB, BC, CD and DA are called its sides.
  • ∠DAB, ∠ABC, ∠BCD and ∠CDA are called its angles, to be denoted by ∠A, ∠B, ∠C and ∠D respectively.
  • The line segments AC and BD are called its diagonals.

Some important facts about quadrilateral:

  • If each angle of a quadrilateral is less than 180°, then it is called convex quadrilateral.
  • If each angle of a quadrilateral is greater than 180°, then it is called concave quadrilateral.

Angle Sum Property of quadrilateral:

  • Sum of interior angles of quadrilateral is 180°

Let us consider some examples:

Example 1:

The three angles of a quadrilateral are 76°, 54° and 108°. Find the measure fourth angle.

Solution:

We know that sum of the angles of a quadrilateral is 360°.

Let the unknown angle be x

76°+  54° +  108° + x = 360°.

 x =  122°.

Example 2: The angles of a quadrilateral are in the ratio of 3 : 4 : 5 : 6.Find all its angles.

Solution:

Let the angles be 3x°, 4x°, 5x° and 6x°.

3x° + 4x° + 5x° + 6x° = 360°.

18x° = 360°.

x° = 20°.

Hence, the angles are 60°, 80°, 100° and 120°.

Example 3: The angles of a quadrilateral are in the ratio of 4 : 6 : 3. If the fourth angle is 100°, find the other angles of a quadrilateral.

Solution:

Let the angles be 4x°, 6x° and 3x°.

4x° + 6x° + 3x° + 100° = 360°.

13x° = 260°.

x° = 20°.

Hence, the angles are  80°,120° and  60°,

TYPES OF QUADRILATERAL

A closed figure with four sides is a quadrilateral. We come across many different types of quadrilaterals every day. It would be interesting to know the types of quadrilaterals, their shapes and basic properties.

Parallelogram:

A quadrilateral is called a parallelogram, if both pairs of its opposite sides are parallel. 

In the figure given below, ABCD is a quadrilateral in which:

AB ∥ DC and AD ∥ BC. 

So, ABCD is a parallelogram.

Rhombus:

A parallelogram having all sides equal is called a rhombus.

In the figure given below, ABCD is a rhombus in which:

AB ∥ DC, AD ∥ BC and AB = BC = CD = DA.

Rectangle:

A parallelogram in which each angle is a right angle is called a rectangle.

In the figure given below, ABCD is a quadrilateral in which:

AB ∥ DC, AD ∥ BC and ∠A = ∠B = ∠C = ∠D = 90°.

So, ABCD is a rectangle.

Square:

A parallelogram in which all the sides are equal and each angle measures 90° is called a square.

In the figure given below, ABCD is a quadrilateral in which:

AB ∥ DC, AD ∥ BC, AB = BC = CD = DA.

and ∠A = ∠B = ∠ C = ∠D = 90°.

So, ABCD is a square.

Trapezium:

A quadrilateral having exactly one pair of parallel sides is called a trapezium.

In the figure given below, ABCD is a quadrilateral in which AB ∥ DC. So, ABCD is a trapezium.

If non–parallel sides of a trapezium are equal, it is called an isosceles trapezium.

Kite:

A quadrilateral is called a kite if it has two pairs of equal adjacent sides but unequal opposite sides.

In the figure given below, ABCD is a quadrilateral with AB = AD, BC = DC, AD ≠ BC and AB ≠ DC.

So, ABCD is a kite.

Let us consider an example:

Example: In the square PQRS given in the figure below, PQ = 3x – 7 and  QR= x + 3 , find PS.

Solution:

As all sides are equal so, PQ = QR.

3x – 7 = x + 3.

2x =  10.

 x = 5.

PQ = 3x – 7 = 8.

QR = x + 3 = 8.

Hence PS = 8.

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CHAPTER – 6 Natural Vegetation and Wild Life | CLASS 7TH | NCERT GEOGRAPHY IMPORTANT QUESTIONS & MCQS | EDUGROWN

Chapter - 6 Natural Vegetation and Wild Life

MCQs

Question 1.
The growth of vegetation depends on
(a) temperature and moisture
(b) only temperature
(c) only moisture

Answer

Answer: (a) temperature and moisture

Question 2.
Tropical evergreen forests are also called
(a) tropical rain forests
(b) tropical dry forests
(c) tropical deciduous forests
(d) none of these

Answer

Answer: (a) tropical rain forests

Question 3.
Where are tropical evergreen forests found?
(a) India
(b) Brazil
(c) China
(d) None of these

Answer

Answer: (b) Brazil

Question 4.
What is the name of the largest snake found in tropical rainforest?
(a) Anaconda
(b) Black cobra
(c) Two mouth snake
(d) None of these

Answer

Answer: (a) Anaconda

Question 5.
Which of the following is not found in Tropical Deciduous Forests?
(a) Tiger
(b) Elephant
(c) Silver Fox
(d) Monkeys

Answer

Answer: (c) Silver Fox

Question 6.
Where are temperate evergreen forests found?
(a) South east USA
(b) South China
(c) South east Brazil
(d) All of these

Answer

Answer: (d) All of these

Question 7.
In which season do plants shed their leaves in temperate deciduous forests?
(a) Dry season
(b) Wet season
(c) Both (a) and (b)
(d) None of these

Answer

Answer: (a) Dry season

Question 8.
What helps reduce transpiration in Mediterranean trees?
(a) Thick Bark
(b) Wax coated leaves
(c) None of these
(d) Both of these

Answer

Answer: (d) Both of these

Question 9.
What does Taiga mean in Russian language?
(a) Tei-rible
(b) Impure
(c) Pure
(d) Hard

Answer

Answer: (c) Pure

Question 10.
Where are Savannah grasslands located?
(a) Africa
(b) America
(c) Amazon
(d) Brazil

Answer

Answer: (a) Africa

Question 11.
What is the name of the tropical grasslands of Venezuela?
(a) Savanna
(b) Campos
(c) Leanos
(d) Down

Answer

Answer: (c) Leanos

Question 12.
Name the animal found in tropical grasslands.
(a) Camel
(b) Monkey
(c) Giraffe
(d) Cow

Answer

Answer: (c) Giraffe

Question 13.
The temperate grassland of Argentina is called
(a) prairie
(b) veld
(c) steppe
(d) pampas

Answer

Answer: (d) pampas

Question 14.
In which type of climate are thorny bushes mainly found?
(a) Hot and humid tropical climate
(b) Hot and dry desertic climate
(c) Cold Polar climate
(d) None of these

Answer

Answer: (b) Hot and dry desertic climate

Match the contents of Column A with that of Column B

Column AColumn B
1. Trees shed leaves in dry season(a) Brazil
2. Oak, Pine, Eucalyptus(b) Temperate evergreen
3. Chir, Pine, Cedar(c) Coniferous
4. Trees do not shed leaves altogether(d) Tropical evergreen
5. Campos(e) Tropical deciduous
Answer

Answer:

Column AColumn B
1. Trees shed leaves in dry season(e) Tropical deciduous
2. Oak, Pine, Eucalyptus(b) Temperate evergreen
3. Chir, Pine, Cedar(c) Coniferous
4. Trees do not shed leaves altogether(d) Tropical evergreen
5. Campos(a) Brazil

Fill in the blanks with appropriate words:

1. Tropical evergreen forests of Brazil are called …………. of the earth.

Answer

Answer: lungs

2. Mediterranean regions are known as the ………….. for their fruit cultivation.

Answer

Answer: orchards of the world

3. Thick barks and wax coated leaves reduce …………….

Answer

Answer: transpiratign

4. ………….. is the desert of India.

Answer

Answer: Thar

5. Tundra type of vegetation is found in polar regions of Europe and ………….

Answer

Answer: North America

Question 1.
Why was Salima excited? Where had she gone during her summer vacation?
Answer:

  • Salima was excited about the summer camp.
  • She had gone to Manali in Himachal Pradesh alongwith her class friends.

Question 2.
What surprised her during her journey?
Answer:
She was surprised to see the changes in landforms and vegetation. As their bus climbed higher the dense jungles of teak and sal slowly disappeared. Gradually they could see more of coniferous trees with pointed leaves on the hill slopes.

Question 3.
Name the brightest flower on tall trees.
Answer:
Rhododendron is the brightest flower on tall trees at high altitudes.

Question 4.
What do we surmise from Salima’s observations?
Answer:
From Salima’s observations, we surmise that there is a close relationship between height of land and the types of vegetations.

  • With the increase in height climate changes.
  • Climate changes natural vegetation.
  • The growth of vegetation depends on temperature and moisture.
  • It also depends on factors like slope and thickness of soil.

Question 5.
How is natural vegetation classified?
Answer:
Three broad categories of natural vegetation:

  • Forests: Grow in regions of high temperature and rain.
  • Grasslands: Grow in regions of moderate rainfall.
  • Thorny shrubs and scrubs: Grow in dry regions.

Question 6.
What experiences did Salima’s father tell her about a variety of natural vegetation in different parts of different continents? What did Salima realise?
Answer:

  • Salima shared her experience of Himalayan trip with her father.
  • Her father had visited various places in the world.
  • He told Salima about his observation of variety of vegetation in different parts of the different continents.
  • He mentioned about coniferous forests in the sub-polar regions.
  • Thorny bushes in the deserts.
  • Thick tropical hardwood forest in the humid regions and many more.
  • Salima realised that Himalayas have almost all variety of vegetation which one can see while moving from equator to the polar region.

Question 7.
Why do type and thickness of natural vegetation vary from place to place?
Answer:
The type and thickness of natural vegetation vary from place to place because of the variation in the factors like, height, climate (temperature and moisture), slope and thickness of the soils.

Forests

Tropical Evergreen Forests:

Question 1.
Write down the features of Tropical Evergreen Forests.
Answer:
Tropical Evergreen Forests:
Tropical evergreen forests are also called tropical rain forests.

They occur in the region near the equator and close to the tropics.

  • These regions are hot.
  • They receive heavy rainfall during the year.
  • With no dry season, the trees do not shed their leaves altogether.
    They are called evergreen.
  • The thick canopies of the closely spaced trees do not allow the sunlight to penetrate the forest even in day time.
  • Hardwood trees like Rosewood, Ebony, Mahagany are common trees.

Tropical Deciduous Forests

Question 1.
Write the features of Tropical Deciduous Forests.
Answer:
Features of Tropical Deciduous Forests:

  • Tropical deciduous forests are monsoonal forests.
  • They are found in a large part of India, northern Australia and in Central America.
  • These regions experience seasonal changes.
  • Trees shed their leaves in the dry season to conserve water.
  • The hardwood trees are found in these forests.
  • They are Sal, Teak, Neem, and Shisham.
  • Hardwood trees are extremely useful for making furnitures, transport and constructional materials.
  • Tiger, Lion, Elephants are the common animals of these regions.

Temperate Evergreen Forests

Question 1.
Where are Temperate Evergreen forests located?
Answer:
Mid latitudinal coastal regions have temperate Evergreen forests. Commonly the eastern margins of the continents like south east USA, south China or south east Brazil have these forests. Both hard and soft wood trees like oak, pine, eucalyptus are found in temperate evergreen forests.

Temperate Deciduous Forests

Question 1.
Describe major features of Temperate Deciduous Forest.
Answer:
Major Features of Temperate Deciduous Forest:

  • Going towards higher latitudes, there are more temperate deciduous forests.
  • They are found in the north-eastern part of USA, China, New Zealand, Chile.
  • They are also found in the coastal regions of Western Europe.
  • They shed their leaves in the dry season.
  • The common trees of these forests are oak, ash, beech etc.
  • Deer, foxes, wolves, are the animals which commonly live in these forests.
  • Common birds are pheasants and monals.

Mediterranean Vegetation

Question 1.
Which region is called the “orchards of the world” and why?
Answer:
Mediterranean region is known as the orchards of the world because of their fruit cultivation.

Question 2.
Write major features of Mediterranean Vegetation.
Answer:
Major Features of Mediterranean Vegetation:

  • Most of the east and the north-east margins of the continents are covered with temperate evergreen and deciduous trees.

The west and the south west margins of the continents are different.

  • They have Mediterranean vegetation.
  • It is mostly found in the areas around the Mediterranean sea in Europe, Africa and Asia.
  • This vegetation is also found outside the actual Mediterranean region in California in the U.S.A., South-West Africa.
  • These regions are marked for hot dry summers and rainy mild winters.
  • Citrus fruits like oranges, figs, olives and grapes are commonly cultivated here because people have removed the natural vegetation in order to cultivate what they want to. There is not much wildlife here.

Coniferous Forests

Question 1.
Give an account of the main features of Coniferous Forests.
Answer:
Major Features of Coniferous Forests

  • In the higher latitudes (50°-70°) of Northern Hemisphere coniferous forests are found.
  • They are also called as Taiga.
  • They are also found in the higher latitudes.
  • They are also found in Himalayas in abundance.
  • They are tall, softwood, evergreen trees.
  • These woods are used in making paper and newsprint.
  • Match boxes and packing boxes are also made from softwood.
  • Chir, Pine, Cedar are the important variety of trees in these forests.
  • Silver fox, Mink, Polar bear are the common animals found in these forests.

Grasslands

Tropical Grasslands

Question 1.
Describe main features of Tropical Grasslands.
Answer:
Main features of Tropical Grasslands:

  • Tropical grasslands grow on either side of the equator and extend up to the tropics.
  • Grass grows in the areas of moderate to low amount of rainfall.
  • They grow very tall, about 3 to 4 metres in height.
  • Example: Savannah grasslands of Africa.
  • Elephants, Zebras, Giraffes, Deer, Leopards are common wild-life animals in tropical grasslands.

Temperate Grasslands

Question 1.
Write major features of Temperate Grasslands.
Answer:
Mtgor features of Temperate Grasslands:

  • Temperate grasslands are found in the mid latitudinal zones and in the interior part of the continents.
  • Usually, grass here is short and nutritious.
  • Wild buffaloes, bisons, antelopes are common in the temperate grasslands.

Thorny Bushes

Question 1.
Write major features of Thorny Bushes.
Answer:
Thorny bushes are found in dry desert regions like tropical and sub-tropical regions:

  • The vegetation cover is scarce due to less rainfall and extreme temperatures.
  • The trees have thorns to reduce transpiration and thick stems, wax coated leaves and long roots.
  • The main vegetation is cacti, thorny bushes etc.
  • Camel, fox, wolf, goat, sheep are common animals.

Question 2.
Explain major features of Tundra Type of Vegetation.
Answer:
Major features of Tundra Type of Vegetation:

  • Polar regions qre extremely cold.
  • Growth of natural vegetation is very limited here.
  • Only mosses, lichens and very small shrubs grow here during short summer.
  • This vegetation grows in Polar areas of Europe, Asia and North America.
  • The animals of this region have thick fur and thick skin to protect themselves from cold climate conditions.
  • Seal, walruses, reindeer, mink (musk oxen), Arctic owl, polar bear, snow foxes are some of the common animals found in this region.

Question 3.
What was Salima’s observation after seeing the photographs of thick forests?
Answer:
Salima’s father showed her the photographs of thick forests. On the question of why the forests are being cleared he explained that local people wanted land for settlement and agriculture.
Salima wondered if all the forests cleared then from where will we get oxygen, timber, fruits etc? What will happen to the habitats of wildlife?

Question 4.
Do you agree with Salima? Hold a discussion with your friends about the depletion of our diversified flora and fauna. Suggest some measures to conserve them.
Answer:

  • Yes, we agree with Salima.
  • “The students should perform this activity in their class.”

Measures to conserve forests:

  • Afforestation
  • Complete ban on cutting forests.
  • Social and community forestry.
  • Farm Forestry.
  • Plantation of trees in a big way.
  • Planting of 10 plants if one cuts, one tree.
  • Van-Mahotsava.
  • Heavy punishment to poachers and smugglers.

 

 

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CLASS 6TH | UNIT 4: GEOMETRY | TRIANGLES (INCLUDING TYPES,PROPERTIES AND CONSTRUCTION) | REVISION NOTES

Construction of geometrical objects is an important part of geometry. This is nothing but practical geometry. Every object is constructed using certain instruments following certain rules and methods. In this chapter, you will learn about how to construct line segments, angles, triangles and circles by using tools such as ruler and compass.

Things To Remember

  • Constructing a circle given its radius:
    1. Open the compasses and measure the required radius, say 3 cm.
    2. Mark a point O with a sharp pencil where we want the centre of the circle to be.
    3. Place the pointer of the compasses on O.
  • Rotate the compasses to draw the circle. Take care to complete the movement around in one instant.
  • Constructing a line segment of given length:
    1. Draw a line l and mark a point A on it.
    2. Place the compasses pointer on zero mark of the ruler. Open it to place the pencil point upto the required length.
    3. Taking caution that the opening of the compasses has not changed, place the pointer of the compasses at A and make an arc to cut l at B.
    4. AB is the line segment of the required length.
  • Constructing a copy of a given line segment:
    1. Given \ov{AB} whose length is not known.
    2. Fix the compasses pointer on A and the pencil end on B. The opening of the instrument now gives the length of \ov {AB}.
    3. Draw any line l. Choose a point C on l. Without changing the compasses setting, place the pointer on C.
    4. Swing an arc that cuts l at a point, say, D. Now \ov{CD} is a copy of \ov{AB}.
  • Constructing perpendicular to a line through a point on it:
    1. Given a point P on a line l.
    2. With P as the centre and a convenient radius, construct an arc intersecting the line l at two points A and B.
    3. With A and B as centres and a radius greater than AP construct two arcs, which cut each other at Q.
    4. Join PQ. Then PQ is perpendicular to l. We write {PQ}↖{↔} ⊥ l.
  • Constructing perpendicular to a line through a point not on it:
    1. Given a line l and a point P not on it.
    2. With P as the centre, draw an arc which intersects line l at two points A and B.
    3. Using the same radius and with A and B as centres, construct two arcs that intersect at a point, say Q, on the other side.
    4. Join PQ. Then PQ is perpendicular to l. We write {PQ}↖{↔} ⊥ l.
  • Constructing the perpendicular bisector of a line segment:
    1. Draw a line segment \ov{AB} of any length.
    2. With A as the centre, using compasses, draw a circle. The radius of your circle should be more than half the length of \ov{AB}.
    3. With the same radius and with B as the centre, draw another circle using compasses. Let it cut the previous circle at C and D.
    4. Join \ov{CD}. It cuts \ov{AB} at O. Use your divider to verify that O is the midpoint of \ov{AB}. Also, verify that ∠COA and ∠COB are right angles. Therefore, \ov{CD} is the perpendicular bisector of \ov{AB}.
  • Constructing an angle of a given measure:
    1. Draw \ov{AB} of any length.
    2. Place the centre of the protractor at A and the zero edge along \ov{AB}.
    3. Start with zero near B. Mark point C at the required angle measure, say 40°.
    4. Join AC. ∠BAC is the required angle.
  • Constructing a copy of an angle of unknown measure:
    Given ∠A, whose measure is not known.
    1. Draw a line l and choose a point P on it.
    2. Place the compasses at A and draw an arc to cut the rays of ∠A at B and C.
    3. Use the same compasses setting to draw an arc with P as the centre, cutting l in Q.
    4. Set your compasses to the length BC with the same radius.
    5. Place the compasses pointer at Q and draw the arc to cut the arc drawn earlier in R.
    6. Join PR. This gives us ∠P. It has the same measure as ∠A. This means ∠QPR has the same measure as ∠BAC.
  • Constructing bisector of an angle:
    Let an angle, say, ∠A be given.
    1. With A as the centre and using compasses, draw an arc that cuts both rays of ∠A. Label the points of intersection as B and C.
    2. With B as the centre, draw (in the interior of ∠A) an arc whose radius is more than half the length BC.
    3. With the same radius and with C as the centre, draw another arc in the interior of ∠A. Let the two arcs intersect at D. Then AD is the required bisector of ∠A.
  • Constructing a 60° angle:
    1. Draw a line l and mark a point O on it.
    2. Place the pointer of the compasses at O and draw an arc of convenient radius which cuts the line at a point say, A.
    3. With the pointer at A (as centre), now draw an arc that passes through O.
    4. Let the two arcs intersect at B. Join OB. We get ∠BOA whose measure is 60°.
  • Constructing a 30° angle:
    1. Construct an angle of 60° as shown earlier. Now, bisect this angle. Each angle is 30°.
  • Constructing a 120° angle:
    1. Draw any line PQ and take a point O on it.
    2. Place the pointer of the compasses at O and draw an arc of convenient radius which cuts the line at A.
    3. Without disturbing the radius on the compasses, draw an arc with A as the centre which cuts the first arc at B.
    4. Again without disturbing the radius on the compasses and with B as the centre, draw an arc which cuts the first arc at C.
    5. Join OC, ∠COA is the required angle whose measure is 120°.
  • Constructing a 90° angle:
    1. Construct a perpendicular to a line from a point lying on it, as discussed earlier. This is the required 90° angle.
  • Constructing a triangle given all three sides:
    Constructing a ΔABC such that AB = 6 cm, BC = 5 cm and CA = 7 cm.
    1. Draw one of the sides say AB = 6 cm.
    2. Using compasses and taking A as the centre, draw an arc of radius 7 cm.
    3. With B as the centre, draw an arc of radius 5 cm, that cuts the first arc at the point C.
    4. Join AC and BC. ΔABC is the required triangle.
  • Constructing a triangle when two sides and the included angle is given:
    Constructing a ΔABC such that AB = 5 cm, ∠A = 60° and CA = 8 cm.
    1. Draw AB = 5 cm.
    2. With the help of a compass construct &angPAB = 60°.
    3. With A as centre and radius 5 cm cut AP at point C.
    4. Join BC. ΔABC is the required triangle.
  • Constructing a triangle when two angles and included side is given:
    Constructing ΔABC such that AB = 4 cm, ∠A = 30°, ∠B = 60°.
    1. Draw AB = 4 cm.
    2. At A construct ∠QAB = 30°.
    3. At B construct ∠PBA = 60°.
    4. AQ and BP intersect each other at C. ΔABC is the required triangle.
  • Constructing the circumcircle of a triangle:

A circle that passes through all the three vertices of a triangle is called the circumcircle of the triangle.

  • The point where the perpendicular bisectors of the sides of a triangle meet is called the circumcenter. Here O is the circumcenter.
  • OA = OB = OC = radius of circumcircle = Circumradius.
  • Constructing the in-circle of a triangle:

A circle drawn inside a triangle such that it touches all the three sides of the triangle is called the in-circle of the triangle.

  • The point where the bisectors of the angles of a triangle meet, is called incenter. Here I is the incenter.
  • The length of the perpendicular, here IP, is called the inradius.

A polygon is a plane figure with a minimum of three straight lines and three angles.

A triangle is a polygon with three sides. A triangle consists 3 vertices and 3 sides encompassing 3 angles. The sum of the interior angles of a triangle is always 180 degrees.

In this chapter, you will learn about types of triangles and their properties.

Triangles: A triangle is a plane figure bounded by three line segments.

Vertex: Vertex of a triangle is a point where any two of its sides meet.

Angles:

  • Sum of interior angles of a triangle is always 180°.
  • An interior angle of a triangle can be represented by the letter representing the corresponding vertex.
  • When any side of a triangle is extended, the angle formed outside the triangle is called an exterior angle.
  • An exterior angle of a triangle is an adjacent and supplementary angle to the corresponding interior angle of a triangle.
  • An exterior angle is equal to the sum of opposite interior angles.

Types of triangles according to angles

  • If each angle of a triangle is acute i.e. less than 90°, it is called acute angled triangle.
  • If each angle of a triangle is equal to  90°, it is called right angled triangle.
    • In a right angled triangle, the side opposite to the right angle is called hypotenuse and it is the largest side of the right angled triangle.             
  • If each angle of a triangle is obtuse i.e. greater than 90°, it is called the obtuse angled triangle.

Types of triangles according to sides:

  • A triangle with at least two sides equal is called isosceles triangle.
  • PQ =PR,so ∠R = ∠P.
  • A triangle with all sides equal is called equilateral triangle. Each interior angle of the equilateral triangle = (180°/3) = 90°.
  • If the three sides of a triangle are unequal then it is called scalene triangle.

Let us consider an example:

Example:

Find the value of x in the figure given  below:

Solution:

∠ACD = ∠A + ∠B.

115° = 2x + 3x.

4x = 115°.

x = 23°.

It is important to learn construction of triangles. For the construction of a triangle, it is not mandatory to have all its dimensions and angles. A triangle can be constructed given any one of the following set of measurements:

  • The length of two sides and measurement of the angle associated.
  • Measurements of two angles and length of the side associated.
  • For a right-angled triangle, the length of one side and the length of the hypotenuse.
  • The length of all the three sides of a triangle.

In this chapter, you will learn construction of triangles with examples.

We shall be constructing a triangle when any of the following conditions are given:

  • The length of three sides.
  • The length of two sides and angle included between these two sides.
  • Any two angles and the included side i.e. the side common to both angles.

Here are some examples:

Example 1:

Construct a triangle ABC such that BC = 4cm, AC = 6cm and AB = 7. cm.

Solution:

Steps:

1) Draw line segment AB = 7.6 cm

2) Taking A as the centre, draw an arc of radius 6 cm.

3)  Taking B as the centre, draw an arc of radius 4 cm which cuts the previous arc at C.

4) Join AC and BC.

ABC is the required triangle. (Refer to the figure on the left side).

Example 2: Construct a triangle ABC such that BC = 5 cm, ∠ABC = 60° and AB = 3cm.

Solution:

Steps:

1) Draw line segment BC  = 5 cm

2) Construct  ∠PBC = 60°

3)  Taking B as the centre, draw an arc of radius 3 cm which cuts BP at A such that BA = 3 cm.

4) Join A and C.

ABC is the required triangle. (Refer to the figure on the right side).

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CLASS 6TH | UNIT 4: GEOMETRY | ANGLES (WITH THEIR TYPES)| REVISION NOTES

Angles are useful in many situations in day-to-day life.

In this chapter, you will learn about adjacent and vertically opposite angles.

Adjacent angle: Two angles are said to be adjacent angles if,

  • They have a common vertex.
  • They have one common arm.
  • The other arms of the angles are on the opposite sides of the common arm.
  • Angle AOB and BOC are adjacent angles.

Vertically opposite angles:

  • When two straight lines intersect, the angles on the opposite sides of their point of intersection are called vertically opposite angles.

Congruent angles: Angles having the same angular measurement value are said to be congruent angles.

The word complementary takes its origin from the Latin completum which means “completed” since
the right angle is believed to be a complete angle.  The word supplement comes from Latin supplere, which means to “supply” what is needed.

The two angles which add up to 90 degrees is said to be complementing each other. Similarly, two angles which add up to 180 degrees are said to be supplementary angles.

Complementary angle: When the sum of the measures of two angles is 90°, such angles are called complementary angles and each angle is called a complement of the other.

Supplementary angles: When the sum of the measures of two angles is 180°, such angles are called supplementary angles and each of them is called a supplement of the other.

When two straight lines meet at a point an angle is formed. Angles can be seen every day. When you are sitting in a room, you can see an angle at the meeting point of two walls. When you open a book holding it straight, the two pages are open at a certain angle.

The applications of angles are plenty. They are essential in architecture, to make furniture, clocks and so on.

In this chapter, you will learn about angles.

Angle: Two different rays starting from the same fixed point forms an angle. Symbol ∠ is used to represent an angle.

The measure of the Angle: The amount of turning which one arm must be turned about the vertex to bring it to the position of the other arm is called the measure of an angle.

Interior of the Angle: It is the region that lies within the angle.

Exterior of the Angle: It is the region that lies outside the angle.

The unit of measurement of angles is degrees. ° is used to represent degrees.

A protractor is a semi-circular plastic marked in degrees from 0 to 180° on its semi-circular part is used to measure angles.

Types of angles:

  • Complete angle: An angle of measure 3600 is called a complete angle.
  • Right angle: An angle that measures 900 is called a right angle. A right angle makes a quarter revolutions. (Shown in the left side figure below).
  • Straight angle: An angle that measures 1800 is called a straight angle. A straight angle makes a half revolution. (Shown in the right side figure below).
  • Acute angle: An angle that measures less than 900 is called an acute angle.
  • Obtuse angle: An angle that measures more than 900 and less than 1800 is called an obtuse angle. (Shown in the left side figure below).
  • Reflex angle: An angle that measures more than 1800 is called a reflex angle. (Shown in the right side figure below).

Sum of angles around a point is always 360°

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CLASS 6TH | UNIT 4: GEOMETRY | RECOGNISITION OF SOLIDS | REVISION NOTES

You come across many solids every day. The football that you play, the book that you read, the LPG cylinder used for cooking and so on are all solids. Unlike 2D shapes, a solid has length, breadth and depth.

In this chapter, you will learn about solids and recognition of various solid shapes.

Solid: An object that occupies space and has a fixed space is called solid.

Some of the characteristics of a solid are:

  • Solids have length, breadth and height. It is a three-dimensional figure.
  • Solid objects have only three main views.
  • Top view.
  • Side view.
  • Front view.

Cuboid:

Cuboid is solid or hollow which has 6 rectangular faces.

  • It is a three dimensional solid.
  • A cuboid has 12 edges.
  • A cuboid has 8 vertices. 

Cube:

Cube is a symmetrical three-dimensional shape, either solid or hollow contained by six equal squares.

  • Each face of a cube is square.
  • Cube has 6 faces.
  • Cube has 12 edges.
  • Cube has 8 corners.

Cylinder:

Cylinder is a solid or hollow geometrical figure with a curved side and two identical circular flat ends.  

  • Cylinder has  2 edges, 3 faces but no vertex.

Sphere:

Sphere is a round solid or hollow figure with every point on its surface equidistant from its centre.

  • A sphere is a 3D figure with no vertex, no edges and only1 surface.

Cone:

Cone is a solid or hollow object which tampers from a circular base to a point.

  • Cone is a 3D figure with 1 vertex, 1 edge and 2surfaces.

Prism:

Prism is a solid geometrical figure whose two ends are similar, equal and parallel rectilinear figures and whose sides and faces are either parallelograms or rectangles.

  • It has 3 faces,9 edges, and 6 vertices.
  • Prism is a solid whose side faces are ||gm and whose end basses are two parallel and congruent polygons.

Pyramid:

Pyramid is a solid whose base is a plane rectilinear figure such as triangle and whose side faces are triangles with a common vertex.

  • If the base of the pyramid is quadrilateral then it is called a quadrilateral pyramid.
  • If the base of the pyramid is triangle then it is called a triangular pyramid.

Euler’s formula:

For a 3-D solid,

  • V stands for the number of vertices.
  • E stands for the number of edges.
  • F stands for the number of faces.

Euler’s formula is V + F – E = 2.

Drawing a cube:

  • The two types of sketches for drawing a cube are oblique and isometric.
  • An isometric paper has dots or lines, marked on it dividing the paper into small equilateral triangles.

Cube:

Steps:

  1. Take a squared paper.
  2. Draw the front face.
  3. Draw the opposite face of the same size.
  4. Join the corresponding corners.
  5. Draw the figure with hidden edges dotted.
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