Yearly Archives: 2022

In This Post we are  providing Chapter- 1 THE SOLID STATE NCERT MOST IMPORTANT QUESTIONS for Class 12 CHEMISTRY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS  can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter

NCERT MOST IMPORTANT QUESTIONS ON THE SOLID STATE

Question 1.
Give reason:
(a) Why is Frenkel defect found in AgCI?
(b) What is the difference between phosphorus doped and gallium doped silicon semiconductors? (CBSE Sample Paper 2011)
Answer:
(a) Due to small size of Ag⁺ ion, it can fit into interstitial sites.
(b) Phosphorus doped silicon is n-type semiconductor while gallium doped silicon is p-type semiconductor.

Question 2.
Why does LiCl acquire pink colour when heated in Li vapours? (CBSE Sample Paper 2011)
Answer:
On heating LiCl in Li vapours, the excess of Li atoms deposit on the surface of the crystal. The CT ions diffuse to the surface of the crystal and combine with Li atoms to form LiCl. The electrons produced by ionisation of Li atoms diffuse into the crystal and get trapped at anion vacancies called F-centres. These absorb energy from visible light and radiate pink colour.

Question 3.
Account for the following:
(i) Schottky defects lower the density of related solids.
(ii) Conductivity of silicon increases on doping it with phosphorus. (C.B.S.E. 2013)
Answer:
(i) In Schottky defect, there are holes due to missing cations and anions. Due to the presence of holes in solid, the density decreases.

(ii) Pure silicon has a network lattice in which all the four valence electrons are bonded to four other atoms. Therefore, it is an insulator. However, when silicon is doped with phosphorus having five valence electrons, the impurity leads to excess of electrons after forming four covalent bonds like silicon. The extra electrons serve to conductivity and therefore, the conductivity of silicon doped with phosphorus increases.

Question 4.
(i) What type of non-stoichiometric point defect is responsible for the pink colour of LiCl?
Answer:
Metal excess defect due to anion vacancies filled by free electrons i.e. F-centres.

(ii) What type of stoichiometric defect is shown by NaCI?
Answer:
Schottky defect.

OR

How will you distinguish between the following pairs of terms:
(i) Tetrahedral and octahedral voids
Answer:
Tetrahedral void is surrounded by 4 constituent particles (atoms, molecules or ions). Octahedral void is surrounded by 6 constituent particles (atoms, molecules or ions).

(ii) Crystal lattice and unit cell? (C.B.S.E. 2014)
Answer:
A regular three dimensional arrangement of points in space is called crystal lattice.
The smallest repeating pattern in crystal lattice which when repeated in three dimensional space gives the entire lattice is called the unit cell.

Question 5.
An element crystallises in a fcc lattice with cell edge of 250 pm. Calculate its density if 300 g of this element contain 2 × 10²⁴ atoms.
Answer:
Length of edge, a = 250 pm = 250 × 10^-12 m
= 250 × 10^-10 cm
Volume of unit cell = (250 × 10^-10 cm)³
= 15.625 × 10^-24 cm³
Mass of unit cell = No. of atoms in unit cell × Mass of each atom
Since the element has fcc arrangement, the number of atoms per unit cell, Z = 4
Mass of an atom = \(\frac{300}{2 \times 10^{24}}\) g
∴ Mass of unit cell = \(\frac{300}{2 \times 10^{24}}\) x 4
= 6.0 × 10^-22 g

Question 6.
How can you determine the atomic mass of an unknown metal if you know its density and the dimension of its unit cell? Explain.
Answer:
Consider a unit cell of edge a cm
Volume of unit cell = a³ cm³

Mass of unit cell = No. of atoms in a unit cell × Mass of each atom = Z × m …… (ii)
Mass of an atom present in a unit cell

Knowing density (d), edge length (a), number of atoms per unit cell (Z) and Avogadro’s number (6.02 × 10²³), atomic mass can be calculated.

Question 7.
ZnO turns yellow on heating. Why?
Answer:
When ZnO is heated, it loses oxygen as:

The Zn²⁺ ions are entrapped in the interstitial sites and electrons are entrapped in the neighbouring interstitial sites to maintain electrical neutrality. This results in metal excess defect. Due to the presence of free electrons in the interstitial sites the colour is yellow.

Question 8.
(a) What type of semiconductor is obtained when silicon is doped with boron?
Answer:
(a) When silicon is doped with boron having three valence electrons, the bonds formed create electron deficient sites called holes. Under the influence of applied electric field, one electron from neighbouring atom moves to fill the hole but creates another hole at its own place. Therefore, the electrical conductance is due to movement of positive holes. Therefore, this type of semi-conductor is called p-type semi-conductor.

(b) What type of magnetism is shown in the following alignment of magnetic moments?
↑    ↑    ↑    ↑   ↑   ↑    ↑
Answer:
Ferromagnetic.

(c) What type of point defect is produced when AgCI is doped with CdCl₂?
Answer:
CdCl₂ on adding to AgCl introduces impurity defect. The addition of one Cd²⁺ ion will replace two Ag⁺ ions to maintain electrical neutrality. One of the positions of Ag⁺ will be occupied by Cd²⁺ ion and the other will be left as a hole. Thus, a hole is created similar to Schottky defect.

Question 9.
Account for the following:
(i) Schottky defects lower the density of related solids.
Answer:
In Schottky defect, there are holes due to missing cations and anions. Due to the presence of holes in solid, the density decreases.

(ii) Conductivity of silicon increases on doping it with phosphorus.
Answer:
Pure silicon has a network lattice in which all the four valence electrons are bonded to four other atoms. Therefore, it is an insulator. However, when silicon is doped with phosphorus (s²p³) having five valence electrons, the impurity leads to excess of electrons after forming four covalent bonds like silicon. The extra electrons serve to conductivity and therefore, the conductivity of silicon doped with phosphorus increases.

Question 10.
Examine the given defective crystal

Answer the following questions:
(i) What type of stoichiometric defect is shown by the crystal?
Answer:
Schottky defect

(ii) How is the density of the crystal affected by this defect?
Answer:
Density of the crystal decreases.

(iii) What type of ionic substances show such defect?
Answer:
Crystals having
(a) high coordination number and
(b) ions (cations and anions) of almost similar sizes. For example: KCl, KBr.

SHORT ANSWER TYPE QUESTION:

Q1.When can a hazard become a disaster?

Answer
A hazard can become a disaster when it becomes active. A disaster causes losses to property and life on a large scale.
Q2. Why are there more earthquakes in the Himalayas and in the north-eastern region of India?
Answer

The Indian plate is moving at a speed of one centimetre per year towards the north and northeastern direction and the movement of plates is being constantly obstructed by the Eurasian plate from the north. This result in accumulation of energy at different points of time. Excessive accumulation of energy results in building up of stress, which ultimately leads to the breaking up of the lock and the sudden release of energy causes earthquakes in the Himalayas and in the north-eastern region of India

Q3. What are the basic requirements for the formation of a cyclone?

Answer

The basic requirements for the formation of a cyclone are:
• Large and continuous supply of warm and moist air that can release enormous latent heat.
• Strong Coriolis force that can prevent filling of low pressure at the centre.
• Unstable condition through the troposphere that creates local disturbances around which a cyclone develops.
• Absence of strong vertical wind wedge, which disturbs the vertical transport of latent heat.

Q4. How are the floods in Eastern India different from the ones in Western India?

Answer

The flood occur more in Eastern India as compared to Western India because of high rainfall in eastern India than western India. Also, the floods of eastern India are more disastrous in comparison to western India.

Q5. Why are there more droughts in Central and Western India?
Answer

Central and Western India experiences less rainfall because the intensity of monsoon winds becomes weak as they reach in these areas.

Q6. Identify the Landslide-prone regions of India and suggest some measures to mitigate the disasters caused by these.
Answer

The Landslide-prone regions of India are:
• Young mountainous areas in the Himalayas and Andaman and Nicobar.
• High rainfall regions with steep slopes in the Western Ghats and Nilgiris.
• The north-eastern regions.
• Trans-Himalayan areas of Ladakh and Spiti (Himachal Pradesh)
• Undulated yet stable relief and low precipitation areas in the Araval
• Rain shadow areas in the Western and Eastern Ghats and Deccan plateau.• Landslides due to the mining and subsidence are most common in the states like Jharkhand, Orissa, Chhattisgarh, Madhya Pradesh, Maharashtra, Andhra Pradesh, Karnataka etc.

Some measures to mitigate the disasters are:
• Restriction on the construction and other developmental activities such as roads and dams, limiting
agriculture to valleys.
• Areas with moderate slopes, and control on the development of large settlements in the high vulnerability zones, should be enforced.
• Terrace farming should be encouraged in the northeastern hill states where Slash and Burn/Shifting
Cultivationis still prevalent.
Q7. What is vulnerability? Divide India into natural disaster vulnerability zones based on droughts and suggest some mitigation measures.
Answer

Vulnerability means the risk becoming victim to the disaster.

On the basis of severity of droughts, India is divided into following regions:

• Extreme Drought Affected Areas: Most parts of Rajasthan, particularly areas to the west of the Aravali hills, i.e. Marusthali and Kachchh regions of Gujarat. Included here are also the districts like Jaisalmer and Barmer from the Indian desert that receive less that 90 mm average annual rainfall.

• Severe Drought Prone Area: Parts of eastern Rajasthan, most parts of Madhya Pradesh, eastern parts of Maharashtra, interior parts of Andhra Pradesh and Karnataka Plateau, northern parts of interior Tamil Nadu and southern parts of Jharkhand and interior Odisha are included in this category.

• Moderate Drought Affected Area: Northern parts of Rajasthan, Haryana, southern districts of Uttar Pradesh, the remaining parts of Gujarat, Maharashtra except Konkan, Jharkhand and Coimbatore plateau of Tamil Nadu and interior Karnataka are included in this category. The remaining parts of India can be considered either free or less prone to the drought.

Some mitigation measures are:

Identification of ground water potential in the form of aquifers.• Transfer of river water from the surplus to the deficit areas.• Planning for inter-linking of rivers and construction of reservoirs and dams.• Remote sensing and satellite imageries can be useful in identifying the possible river-basins that can be inter-linked and in identifying the ground water potential.

Q8.When can developmental activities become the cause of disasters?

Answer

There are many times when developmental activities carried by human beings that are directly responsible for disasters.

Bhopal Gas tragedy, Chernobyl nuclear disaster, wars, release of CFCs (Chlorofluorocarbons) and increase of green house gases, environmental pollutions like noise, air, water and soil are some of the disasters which are created due to developmental activities done by humans. 
There are some other activities of human beings that accelerate or intensify disasters indirectly. Landslides and floods due to deforestation, unscientific land use and construction activities in fragile areas are some of the disasters that are the results of indirect human actions.
The human-made disasters have increased both in their numbers and magnitudes over the years and serious efforts are necessary are on at various levels to prevent and minimise their occurrences.

Long Answer Type Questions:

Q1.Explain about different types of drought.
Answer:
Different types of droughts are as follows:

• Meteorological Drought: It is a situation when there is a prolonged period of inadequate rainfall marked with mal-distribution of the same over time and space.
• Agricultural Drought: It is also known as soil moisture drought, characterised by low soil moisture that is necessary to support the crops, thereby resulting in crop failures. Moreover, if an area has more than 30 percent of its gross cropped area under irrigation, the area is excluded from the drought-prone category.
• Hydrological Drought: It results when the availability of water in different storages and reservoirs like aquifers, lakes, reservoirs, etc. falls below what the precipitation can replenish.
• Ecological Drought: When the productivity of a natural ecosystem fails due to shortage of water and as a consequence of ecological distress, damages are induced in the ecosystem. Various parts of India experience these droughts recurrently which result in some serious socio-economic and ecological problems.

Q2.On the basis of past experiences, frequency and certain causal relationships with the controlling factors like geology, geomorphic agents, slope, land-use, vegetation cover and human activities, India has been divided into how many zones?
Answer:
On the basis of past experiences, frequency and certain causal relationships with the controlling factors like geology, geomorphic agents, slope, land-use, vegetation cover and human activities, India has been divided into a number of zones.

1. Very High Vulnerability Zone: Highly unstable, relatively young mountainous areas in the Himalayas and Andaman and Nicobar, high rainfall regions with steep slopes in the Western Ghats and Nilgiris, the north-eastern regions, along with areas that experience frequent ground-shaking due to earthquakes, etc. and areas of intense human activities, particularly those related to construction of roads, dams, etc. are very highly vulnerable.

2. High Vulnerability Zone: Areas that have almost similar conditions to those included in the very high vulnerability zone are also included in this category. All the Himalayan states and the states from the north-eastern regions except the plains of Assam are included in the high vulnerability zones.

3. Moderate to Low Vulnerability Zone: Areas that receive less precipitation such as Trans-Himalayan areas of Ladakh and Spiti, undulated yet stable relief and low precipitation areas in the Aravali, rain shadow areas in the Western and Eastern Ghats and Deccan plateau also experience occasional landslides. Landslides due to mining and subsidence are most common in states like Jharkhand, Orissa, Chhattisgarh, Madhya Pradesh, Maharashtra, Andhra Pradesh, Karnataka, Tamil Nadu, Goa and Kerala.

4. Other Areas: The remaining parts of India, particularly states like Rajasthan, Haryana, Uttar Pradesh, Bihar, West Bengal, Assam and Coastal regions of the southern States are safe as far as landslides are concerned.

SHORT ANSWER TYPE QUESTION:

Q1. What is soil?

Answer
Soil is the mixture of rock debris and organic materials which develop on the earth’s surface. Components of the soil are mineral particles, humus, water and air.

Q2.What are the main factors responsible for the formation of soil?
Answer
The major factors affecting the formation of soil are relief, parent material, climate, vegetation and other life-forms and time.

Q3.Mention the three horizons of a soil profile.
Answer
There are three horizons of a soil profile:
• ‘Horizon A’ is the topmost zone, where organic materials have got incorporated with the mineral matter, nutrients and water, which are necessary for the growth of plants.
• ‘Horizon B’ is a transition zone between the ‘horizon A’ and
• ‘Horizon C’ is composed of the loose parent material.
Q4. What is soil degradation?
Answer
Soil degradation can be defined as the decline in soil fertility, when the nutritional status declines and depth of the soil goes down due to erosion and misuse. 
Q5. What is the difference between Khadar and Bhangar?
Answer
Khadar is the new alluvium and is deposited by floods annually, which enriches the soil by depositing fine silts while Bhangar represents a system of older alluvium, deposited away from the flood plains.

Q6.What are black soils? Describe their formation and characteristics.
Answer
Black soils are also known as the ‘Regur Soil’ or the ‘Black Cotton Soil’. It covers most of the Deccan Plateau which includes parts of Maharashtra, Madhya Pradesh, Gujarat, Andhra Pradesh and some parts of Tamil Nadu.
The black soil is formed by the weathering of igneous rocks and cooling of lava after a volcanic eruption.
Characteristics of black soils are:
• The black soils are generally clayey, deep and impermeable.
• They swell and become sticky when wet and shrink when dried.
• The black soils are rich in lime, iron, magnesia and alumina.
• They also contain potash.
• The colour of the soil ranges from deep black to grey.
Q7. What is soil conservation? Suggest some measures to conserve soil.
Answer
Soil conservation is a methodology to maintain soil fertility, prevent soil erosion and exhaustion, and improve the degraded condition of the soil.
Some measures to conserve soil are:
• Afforestation should be encouraged.
• Over-grazing and shifting cultivation should be regulated and controlled by educating villagers about the consequences.
• In arid and semi-arid areas, efforts should be made to protect cultivable lands from encroachment by sand dunes through developing shelter belts of trees and agro-forestry.
• Contour terracing should be done in sloppy areas to reduce surface flow.
• Efforts should be made to prevent gully erosion and control their formation. Finger gullies can be eliminated by terracing. In bigger gullies, the erosive velocity of water may be reduced by constructing a series of check dams.
• Lands not suitable for cultivation should be converted into pastures for grazing.
Q8. How do you know that a particular type of soil is fertile or not? Differentiate between naturally determined fertility and culturally induced fertility.
Answer
We can know about the fertility of a particular type of soil by having a test of the soil sample. To check fertility of the soil we need to know about their inherent characteristics and external features such as texture, colour, slope of land and moisture content.
The fertility which is present in a particular type of soil naturally, it is called naturally determined fertility. Some soils have phosphorous, potassium, calcium, humus content and nitrogen naturally.
Some soils are made fertile by adding fertilizers and manures, it is called culturally induced fertility. They are deficient and minerals and humus content.

Long Answer Type Questions:

Q1.Explain about the regions affected by soil erosion.
Answer:
West Bengal, Uttar Pradesh, Maharashtra, Tamil Nadu, Karnataka, Delhi, Rajasthan and in many parts of the country soil erosion has been a big problem. In mountain regions, there is erosion due to over grazing. In Meghalaya and Nilgiri hills due to potato cultivation and in Himalaya region due to deforestation, soil erosion is increasing.
Wind erosion is significant in arid and semi-arid regions.

In regions with heavy rainfall and steep slopes, erosion by running water is more significant. Water erosion which is more serious and occurs extensively in different’ parts of India, takes place mainly in the form of sheet and gully erosion. Gully erosion is common on steep slopes. Ravines are widespread, in the Chambal basin. Besides this, they are also found in Tamil Nadu and West Bengal. The country is losing about 8,000 hectares of land to ravines every year.

Q2.Explain about causes responsible for soil erosion.
Answer:
Following causes are responsible for soil erosion:

1. Human Activities: Human activities too are responsible for soil erosion to a great extent. As the human population increases, the demand on the land also increases. Forest and other natural vegetation is removed for human settlement, for cultivation, for grazing animals and for various other needs. Wind and water are powerful agents of soil erosion because of their ability to remove soil and transport it.

2. Deforestation: Deforestation is one of the major causes of soil erosion. Plants keep soils bound in locks of roots, and thus, prevent erosion. They also add humus to the soil by shedding leaves and twigs. Forests have been denuded practically in most parts of India but their effect on soil erosion are more in hilly parts of the country.

3. Wind and water: Wind erosion is significant in arid and semi-arid regions.
In regions with heavy rainfall and steep slopes, erosion by running water is more significant. Water erosion which is more serious and occurs extensively in different parts of India, takes place mainly in the form of sheet and gully erosion. Sheet erosion takes place on level lands after a heavy shower and the soil removal is not easily noticeable.

Q3.In India, fertility of soil is also destroyed by over irrigation. Explain.
Answer:
A fairly large area of arable land in the irrigated zones of India is becoming saline because of over-irrigation.

• The salt lodged in the lower profiles of the soil comes up to the surface and destroys its fertility.
• Chemical fertilisers in the absence of organic manures are also harmful to the soil.
• Unless the soil gets enough humus, chemicals harden it and reduce its fertility in the long run. This problem is common in all the command areas of the river valley projects, which were the first beneficiaries of the Green Revolution.
• According to estimates, about half of the total land of India is under some degree of degradation.

Every year, India loses millions of tonnes of soil and its nutrients to the agents of its degradation, which adversely affects our national productivity. So, it is imperative to initiate immediate steps to reclaim and conserve soils.

Q4.Wind and water are two important agents of soil erosion. Explain.
Answer:
Wind and water are powerful agents of soil erosion because of their ability to remove soil and transport it. Wind erosion is significant in arid and semi-arid regions. Erosion by running water is more significant in regions with heavy rainfall and steep slopes. Water erosion which is more serious and occurs extensively in different parts of India, takes place mainly in the form of sheet and gully erosion. Sheet erosion takes place on level lands after a heavy shower and the soil removal is not easily noticeable.

But it is harmful since it removes the finer and more fertile top soil. Gully erosion is common on steep slopes. Gullies deepen with rainfall, cut the agricultural lands into small fragments and make them unfit for cultivation. A region with a large number of deep gullies or ravines is called bad land topography. Ravines are widespread, in the Chambal basin. They are also found in Tamil Nadu and West Bengal. The country is losing about 8,000 hectares of land to ravines every year.

Q5.Explain about laterite soils.
Answer:
The word ‘laterite’ has been derived from a Latin word ‘later’ meaning ‘brick’. The laterite soil is widely spread in India and is mainly found on the summits of the Western Ghats, Eastern Ghats, Rajmahal Hills, Vindhyas, Satpuras and Malwa plateau. It’s well- developed in southern Maharashtra, and parts of Orissa, West Bengal, Karnataka, Andhra Pradesh, Kerala, Bihar, Assam and Meghalaya.

• The laterite soil is formed under conditions of high temperature and heavy rainfall with alternate wet and dry periods.
• Such climatic conditions promote leaching of soil. Leaching is a process in which heavy rains wash away the fertile part of the soil.
• The laterite soil is red in colour and composed of little clay and much gravel of red sandstones.
• Laterite soil generally is poor in lime and deficient in nitrogen. The phosphate contents are generally high.

Due to intensive leaching, the laterite j soil generally lacks fertility and is of low value for crop production. But when manured and timely irrigated, the soil is suitable for producing plantation crops like tea, coffee, rubber, coconut, areca nut, etc. It also provides valuable building materials.

SHORT ANSWER TYPE QUESTION:

Q1.What is natural vegetation? Under what climatic conditions are tropical evergreen forests develop?

Answer

Natural vegetation refers to a plant community that has been left undisturbed over a long time, so as to allow its individual species to adjust themselves to climate and soil conditions as fully as possible.
Tropical evergreen forests develop in warm and humid areas with an annual precipitation of over 200 cm and mean annual temperature above 22°C.

Q2. What do you understand by social forestry?

Answer

Social forestry means the management and protection of forests and afforestation on barren lands with the purpose of helping in the environmental, social and rural development.

Q3. Define Biosphere reserves?

Answer

A Biosphere Reserve is a unique and representative ecosystem of terrestrial and coastal areas which are internationally recognised within the framework of UNESCO’s Man and Biosphere (MAB) Programme.

Q4. What is the difference between forest area and forest cover?

Answer

The forest area and forest cover are not the same.

• The forest area is the area notified and recorded as the forest land irrespective of the existence of trees, while the actual forest cover is the area occupied by forests with canopy.

• The forest area is based on the records of the State Revenue Department, while the forest cover is based on aerial photographs and satellite imageries.

• According to state records, the forest area covers 23.28 per cent of the total land area of the country while the actual forest cover in India is only 21.05 percent.

Q5.What steps have been taken up to conserve forests?

Answer

There are various steps taken based on the forest conservation policy. These are:

• Social forestry: It means the management and protection of forests and afforestation on barren lands with the purpose of helping in the environmental, social and rural development. The National Commission on Agriculture (1976) has classified social forestry into three categories. These are Urban forestry, Rural forestry and Farm forestry.

→ Urban forestry: It pertains to the raising and management of trees on public and privately owned lands in and around urban centres such as green belts, parks, roadside avenues, industrial and commercial green belts, etc.–

→ Rural forestry: It lays emphasis on promotion of agro-forestry and community-forestry.

→ Agro-forestry: It is the raising of trees and agriculture crops on the same land inclusive of the waste patches.

• Community forestry: It involves the raising of trees on public or community land such as the village pasture and temple land, roadside, canal bank, strips along railway lines, and schools etc.

• Farm forestry is a term applied to the process under which farmers grow trees for commercial and non-commercial purposes on their farm lands.

Q6.How can people’s participation be effective in conserving forests and wildlife?

Answer

The government can make policies on the conservation of forests and wildlife but it is on the people who take part in this and make them successful. It is mostly the local people who take part in the illegal activities by damaging the environment for their benefits knowingly or unknowingly. The government need the cooperation of common people for ensuring the protection against the deforestation, poaching, hunting etc. This can effective in many ways:

• Holding a regular meeting of local people and make them aware of the advantages of conservation of forests and wildlife.
→ The government officials can inform them about the various policies of the government about the conservation and how they can be part of it.

• Incentives for the good work: The government can provide the incentives to the local people for their good work in protecting the local trees or wildlife which will encourage others to do the same work. Gradually, it will spread to mass scale.

• Various NGOs can also help in doing this activity by providing the skills to the people in conserving forests and wildlife through their experts.

Long Answer Type Questions:

Q1.“Natural vegetation is an outcome of climate.” Substantiate the statement by taking example of Indian vegetation.
Answer:
India is a land of great variety of natural vegetation. Himalayan heights are marked with temperate vegetation; the Western Ghats and the Andaman Nicobar Islands have tropical rain forests.

• Tropical evergreen forests are found in warm and humid areas with an annual precipitation of over 200 cm and mean annual temperature above 22°C. In these forests, trees reach at great heights up to 60 m or above. The semi¬evergreen forests are found in the less rainy parts of these regions.
• Tropical deciduous forests are spread over regions which receive rainfall between 70-200 cm.
• The moist deciduous forests are more pronounced in the regions which record rainfall between 100-200 cm. Dry deciduous forest covers vast areas of the country, where rainfall ranges between 70-100 cm.
• Tropical thorn forests occur in the areas which receive rainfall less than 50 cm. In mountainous areas, the decrease in temperature with increasing altitude leads to a corresponding change in natural vegetation.
• The Himalayan ranges show a succession of vegetation from the tropical to the tundra, with change in the altitude. Deciduous forests are found in the foothills of the Himalayas. It is succeeded by the wet temperate type of forests between an altitude of 1,000-2,000 m. In the higher hill ranges of north-eastern India, hilly areas of West Bengal and Uttarakhand, evergreen broad leaf trees such as oak and chestnut are predominant. Between 1,500-1,750 m, pine forests are also well-developed in this zone, with Chir Pine as a very useful commercial tree.

Q2.Mention the reasons for the decline of wildlife in India?
Answer:
Important reasons for the decline of Wildlife in India are-

• Industrial and technological advancement brought about a rapid increase in the exploitation of forest resources.
• More and more lands were closed for agriculture, human settlement, roads, mining, resources, etc.
• Pressure on forests maintained due to looping for fodder and fuel, wood and removal of small timber by the local people.
• Grazing by domestic cattle caused an adverse effect on wildlife and its habitat.
• Hunting was taken up as a sport by the elite and hundreds of wild animals were killed in a single hunt. Now commercial poaching is rampant.
• Incidence of forest fire.

Q3.According to the statistics received from state records, there are differences in forest area and actual forest cover. Explain.
Answer:
According to state records, the forest area covers 23.28 percent of the total land area of the country. It is important to note that the forest area and the actual forest cover are not the same. The forest area is the area notified and recorded as the forest land irrespective of the existence of trees, while the actual forest cover is the area occupied by forests with canopy.
Forest area is based on the records of the State Revenue Department, while the actual forest cover is based on aerial photographs and satellite imageries.

According to India State of Forest Report 2011, the actual forest cover in India is only 21.05 percent. Of the forest cover, the share of dense and open forests is 12.29 and 8.75 percent respectively. Both forest area and forest cover vary from state to state. Lakshadweep has zero percent forest area; Andaman and Nicobar Islands have 86.93 percent. Most of the states with less than 10 percent of the forest area lie in the north and northwestern part of the country. These are Rajasthan, Gujarat, Punjab, Haryana and Delhi.

States with 10-20 percent forest area are Tamil Nadu and West Bengal. In Peninsular India, excluding Tamil Nadu, Dadra and Nagar Haveli and Goa, the area under forest cover is 20-30 percent. The northeastern states have more than 30 percent of the land under forest. Hilly topography and heavy rainfall are good for forest growth. There is a lot of variation in actual forest cover, which ranges from 9.56 percent in Jammu and Kashmir to 84.01 percent in Andaman and Nicobar Islands.

Q4.On the basis of actual forest cover, in how many categories have Indian states been divided?
Answer:
On the basis of the percentage of the actual forest cover, the states have been grouped into four regions:

• The region of high concentration > 40: It includes Andaman and Nicobar islands, Mizoram, Nagaland, Arunachal Pradesh which have 80% of their total area under forests. Manipur, Tripura, Meghalaya, Sikkim and Dadar and Haveli have forest cover between 40-80%.
• The region of medium concentration 20-40: It includes Madhya Pradesh, Odisha, Goa, Kerala, Assam and Himachal Pradesh. In Goa, actual forest cover is 33.27% which is highest in this range. Thereafter, comes Assam and Orissa. In other states 30% of their area is covered with forests.
• The region of low concentration 10-20: It includes states of Maharashtra, Andhra Pradesh, Karnataka, Tamil Nadu, Bihar and Uttar Pradesh.
• The region of very low concentration < 10: It includes states of Rajasthan, Punjab, Haryana, and Gujarat. It also includes union territories of Delhi and Chandigarh. It also includes West Bengal.

Q5.Explain in short about four important Biospheres of India.
Answer:
Four Biosphere Reserves have been recognised by the UNESCO on World Network of Biosphere Reserves. These are as follows:

1. Nilgiri Biosphere Reserve: The Nilgiri Biosphere Reserve (NBR) is the first of the fourteen biosphere reserves of
India. It was established in September 1986. It embraces the sanctuary complex of Wyanad, Nagarhole, Bandipur and Mudumalai, the entire forested hill slopes of Nilambur, the Upper Nilgiri plateau, Silent Valley and the Siruvani hills. The total area of the biosphere reserve is around 5,520 sq. km. The largest south Indian population of elephant, tiger, gaur, sambar and chital as well as a good number of endemic and endangered plants are also found in this reserve. The topography of the NBR is extremely varied, ranging from an altitude of250 m to 2,650 m. About 80 percent of the flowering plants reported from the Western Ghats occur in the Nilgiri Biosphere Reserve.

2. Nanda Devi Biosphere Reserve: The Nanda Devi Biosphere Reserve is situated in Uttarakhand. It includes parts of Chamoli, Almora, Pithoragarh and Ba’geshwar districts. The major forest types of the reserve are temperate. A few important species are silver weed and orchids like latifolie and rhododendron. The biosphere reserve has a rich fauna like the snow leopard, black bear, brown bear, musk deer, snow- cock, golden eagle and black eagle.

3. Sunderbans Biosphere Reserve: It is located in the swampy delta of the river Ganga in West Bengal. It extends over a vast area of 9,630 sq. km and consists of mangrove forests, swamps and forested islands. Sunderbans is the home of nearly 200 Royal Bengal tigers. More than 170 birds species are known to inhabit these mangrove forests. In the Sunderbans, the mangrove forests are characterised by Heritiera fomes, a species valued for its timber.

4. Gulf of Mannar Biosphere Reserve: The Gulf of Mannar Biosphere Reserve covers an area of 105,000 hectares on the south-east coast of India. It is one of the world’s richest regions from a marine biodiversity perspective. The biosphere reserve comprises 21 islands with estuaries, beaches, forests of the nearshore environment, sea grasses, coral reefs, salt marshes and mangroves.

SHORT ANSWER TYPE QUESTION:

Q1. What are the three important factors which influence the mechanism of Indian weather?
Answer
The three important factors which influence the mechanism of Indian weather are:• Distribution of air pressure and winds on the surface of the earth.
• Upper air circulation caused by factors controlling global weather and the inflow of different air masses and jet streams.
• Inflow of western cyclones generally known as disturbances during the winterseason and tropical depressions during the south-west monsoon period into India, creating weather conditions favourable to rainfall.

Q2. What is the Inter-Tropical Convergene Zone?
Answer
The Inter Tropical Convergence Zone (ITCZ) is a low pressure zone located at the equatorwhere trade winds converge, and so, it is a zone where air tends to ascend.
Q3. What is meant by ‘bursting of monsoon’? Name the place of India which gets the highest rainfall.
Answer
The sudden onset of the moisture-laden winds associated with violent thunder and lightening, is often termed as the “break” or “burst” of the monsoons.Mawsynram in Meghalaya is the place of India which gets the highest rainfall.
Q4. Define ‘climatic region’? What are the bases of Koeppen’s classification?
Answer
 A climatic region has a homogeneous climatic condition which is the result of a combination of factors. The bases of Koeppen’s classification are:• Temperature• Precipitation

Q5.Which type(s) of cyclones cause rainfall in north-western India during winter? Where do they originate?
Answer
Western cyclonic disturbances cause rainfall in north-western India during winter. They originate over the Mediterranean Sea.

Q6.Notwithstanding the broad climatic unity, the climate of India has many regional variations. Elaborate this statement giving suitable examples.
Answer
Due to the influence of monsoon, India as a whole has broad climatic unity. However, the climate of India has many regional variations expressed in the pattern of winds, temperature and rainfall, rhythm of seasons and the degree of wetness or dryness. There are various examples of this:
• Temperature: In the summer the mercury occasionally touches 55°C in the western Rajasthan, it drops down to as low as minus 45°C in winter around Leh. Churu in Rajasthan may record a temperature of 50°C or more on a June day while the temperature in Tawang (Arunachal Pradesh) is 19°C on the same day.
• Rainfall: Cherrapunji and Mawsynram in the Khasi Hills of Meghalaya receive rain fallover 1,080 cm in a year while Jaisalmer in Rajasthan rarely gets more than 9 cm of rainfall during the same period.
• Monsoon: The Ganga delta and the coastal plains of Orissa are hit by strong rain-bearing stormsal most every third or fifth day in July and August while the Coromandal coast, a thousand km to the south, goes generally dry during these months. 
Q7.How many distinct seasons are found in India as per the Indian Meteorological Department? Discuss the weather conditions associated with any one season in detail.
Answer
The meteorological department recognise the following four seasons :(i) the cold weather season(ii) the hot weather season(iii) the southwest monsoon season(iv) the retreating monsoon season.
• The cold weather season: The cold weather season sets in by mid-November in northern India. December and January are the coldest months in the northern plain. The mean daily temperature remains below 21°C over most parts of northern India. The night temperature may be quite low.The Peninsular region of India, however, does not have any well-defined cold weather season. There is hardly any seasonal change in the distribution pattern of the temperature in coastal areas because of moderating influence of the sea and the proximity to equator.
During the winters, the weather in India is pleasant. The pleasant weather conditions, however, at intervals, get disturbed by shallow cyclonic depressions originating over the east Mediterranean Sea and travelling eastwards.
Winter monsoons do not cause rainfall as they move from land to the sea. It is because they have little humidity and due to anti cyclonic circulation on land. So, most parts of India do not have
rainfall in the winter season. However, there are some exceptions, Rainfall occurs in northwestern India due to western disturbances. Central parts of India and northern parts of southern peninsula also get winter rainfall occasionally.

Long Answer Type Questions:

Q1.Explain the important features of Winter Season of India.
Answer:
By October, the rainy season comes to an end all over the country and the days become short and the night become long. The rays of the sun are not overhead. The air turns cooler in the plains marking the coming of the winter season.

The winter season lasts from November to February every year. In the Northern Plains, very cold wind blow making the winter months severe. December and January are the coldest months in the northern plain. The mean daily temperature remains below 21°C over most parts of northern India.

Most of the hilly areas receive heavy snowfall. January is the coldest month in the Northern Plains. The winter season in Peninsular India is mild as a result of the influence of the surrounding water bodies. The coromandel Coast receives heavy rainfall during this season.

The desert is cool during the day but cold at night. The air starts warming up in the month of March, and the weather is neither cold nor hot. This time of early summer is also called the spring season. Every part of our country regularly experiences this cycle of seasons.

Q2.According to Koeppen, in how many groups- can you classify the climate of India?
Answer:
Koeppen identified a close relationship between the distribution of vegetation and climate. He selected certain values of temperature and precipitation and related them to the distribution of vegetation and used these values for classifying the climates. Koeppen introduced the use of capital and small letters to designate climatic groups and types. Koeppen recognised five major climatic groups, four of them are based on temperature and one on precipitation.

• Tropical climates,
• Dry climates,
• Warm temperate climates,
• Cool temperate climates,
• Ice climates

Classification of Indian climatic regions: Amw – Monsoon with short dry season.
Areas: West coast of India south of Goa
As – Monsoon with dry summer
Areas: Coromandel coast of Tamil Nadu
Aw – Tropical savannah.
Areas: Most of the Peninsular plateaus, south of the Tropic of Cancer
Bwhw – Semi-arid steppe climate.
Areas: North-western Gujarat, some parts of western Rajasthan and Punjab
Bwhw – Hot desert. Areas: Extreme western Rajasthan
Cwg – Monsoon with dry winter.
Areas: Ganga plain, eastern Rajasthan, northern Madhya Pradesh, most of North-east India
Dfc – Cold humid winter with short summer.
Areas: Arunachal Pradesh
E – Polar type. Areas: Jammu and Kashmir, Himachal Pradesh and Uttarakhand.

Q3.Explain the spatial variation in the rainfall throughout the country.
Answer:
There is great variation in rainfall throughout the country.

• While Cherrapunji and Mawsynram in the Khasi Hills of Meghalaya receive rainfall over 1,080 cm in a year, Jaisalmer in Rajasthan rarely gets more than 9 cm of rainfall during the same period.
• Tura situated in the Garo Hills of Meghalaya may receive an amount of rainfall in a single day which is equal to 10 years of rainfall at Jaisalmer. While the annual precipitation is less than 10 cm in the north-west Himalayas and the western deserts, it exceeds 400 cm in Meghalaya.
• The highest rainfall occurs along the west coast, on the western Ghats as well as in the sub-Himalayan areas in the north-west and the hills of Meghalaya, rainfall exceeding 200 cm. In some parts of Khasi and Jaintia hills, the rainfall exceeds 1,000 cm. In the Brahmaputra valley and the adjoining hills, the rainfall is less than 200 cm.
• Rainfall between 100-200 cm is received in southern parts of Gujarat, east Tamil Nadu, North-eastern Peninsular covering Orissa, Jharkhand, Bihar, eastern Madhya Pradesh, Northern Ganga Plain along the sub-Himalayas and the Cachar valley and Manipur.
• Western Uttar Pradesh, Delhi, Haryana, Punjab, Jammu and Kashmir, eastern Rajasthan, Gujarat and Deccan Plateau receive rainfall between 50-100 cm.

Q4.Explain the spatial variation in temperature in India.
Answer:
India has hot monsoonal climate which is the prevalent climate in south and south-east Asia.

• While in the summer the mercury occasionally touches 55°C in the western Rajasthan, it drops down to as low as minus 45°C in winter around Leh.
• Churu in Rajasthan may record a temperature of 50°C or more on a June day while the mercury hardly touches 19°C in Tawang (Arunachal Pradesh) on the same day.
• On a December night, temperature in Drass (Jammu and Kashmir) may drop down to minus 45°C while Thiruvananthapuram or Chennai on the same night records 20°C or 22°C.
• In Kerala and in the Andaman Islands, the difference between day and night temperatures may be hardly seven or eight degree Celsius. But in the Thar desert, if the day temperature is around 50°C, at night, it may drop down considerably upto 15°-20°C.
• While snowfall occurs in the Himalayas, it only rains over the rest of the country. Similarly, variations are noticeable not only in the type of precipitation but also in its amount.

Q5.How economic life in India is affected by monsoon?
Answer:
Economic life of India is extremely affected by the monsoon.

• Monsoon is that axis around which revolves the entire agricultural cycle of India. Around 64 % people of India depend on agriculture for their livelihood and agriculture itself is based on south-west monsoon.
• Except Himalayas all the parts of the country have temperature above the threshold level to grow the crops or plants throughout the year.
• Regional variations in monsoon climate help in growing various types of crops.
• Variability of rainfall brings droughts or floods every year in some parts of the country.
• Agricultural property of India depends very much on timely and adequately distributed rainfall. If it fails, agriculture is adversely affected particularly in those regions where means of irrigation are not developed.
• Sudden monsoon burst creates problems of soil erosion over large areas in India.
• Winter rainfall by temperate cyclones in north India is highly beneficial for Rabi crops.
• Regional climatic variation in India is reflected in the vast variety of food, clothes and house types.

Q6.What is Global Warming? What are the effects of Global Warming?
Answer:
Due to global warming the polar ice caps and mountain glaciers would melt and the amount of water in the ocean would increase. It leads to rise in the sea level and melting of glaciers and sea-ice due to warming.

Effects:

• Sea level will rise 48 cm by the end of twenty first century.
• Increase the incidence of annual flooding.
• Insect-borne diseases like malaria, and leads to shift in climatic boundaries, making some regions wetter and other dries.
• Agricultural pattern would shift and human population as well as the ecosystem would experience change.
• The peninsular India would be submerged.
• Global warming refers to the increase in average ground temperatures refers to the increase in average ground temperatures on earth. These higher temperatures across the planet are caused by an intensification of the greenhouse effect.

Q7.What is Break in Monsoon? What are its causes? When is the monsoon expected to break in Kerala and reach the plains of Punjab?
Answer:
During the south-west monsoon period after having rains for a few days, if rain fails to occur for one or more weeks, it is known as break in the monsoon. These dry spells are quite common during the rainy season. These breaks in the different regions are due to different reasons:

• In northern India rains are likely to fail if the rain-bearing storms are not very frequent along the monsoon trough or the ITCZ over this region.
• Over the west coast the dry spells are associated with days when winds blow parallel to the coast.

Breaking of Monsoon:

• Breaking of the Monsoon in Kerala: Beginning of June.
• Reaching Punjab: First week of July.

SHORT ANSWER TYPE QUESTION:

Q1. State the differences between the following.
(i) River Basin and Watershed(ii) Dendritic and Trellis drainage pattern
(iii) Radial and Centripetal drainage pattern
(iv) Delta and Estuary
Answer
(i) River Basin and Watershed

River Basin	Watershed
The catchments of large rivers are called river basins.	The catchments of small rivulets and rills are often referred to as watersheds.
These are larger in the area.	These are small in area.

(ii) Dendritic and Trellis drainage pattern

Dendritic drainage pattern	Trellis drainage pattern
The drainage pattern resembling the branches of a tree is known as dendritic.	When the primary tributaries of rivers flow parallel to each other and secondary tributaries join them at right angles, the pattern is known as trellis.
The drainage pattern of Northern plain is the example of such pattern.	The drainage pattern of Himalayan mountain is the example of such pattern.

(iii) Radial and Centripetal drainage pattern

Radial drainage pattern	Centripetal drainage pattern
When the rivers originate from a hill and flow in all directions, the drainage pattern is known as ‘radial’.	When the rivers discharge their waters from all directions in a lake or depression, the pattern is known as ‘centripetal’.
The rivers originating from the Amarkantak range is the example of such pattern.	Sambhar Lake of Rajasthan is the example of such pattern.

(iv) Delta and Estuary

Delta	Estuary
A Delta is a triangular landmass formed at the mouth of the river.	An Estuary is a funnel shaped formed at the mouth of the river.
It is formed in the regions of low tides and coastal plains.	It is formed in the regions of high tides and rift valleys.
These are extremely fertile and support agriculture.	They provide fishing ground and support inland transportation.
The rivers like Ganga and Brahmaputra form deltas.	The rivers like Narmada and Tapi form estuaries.

Q2.What are the socio-economic advantages of inter-linking of rivers in India?

Answer

The socio-economic advantages of inter-linking of rivers in India are:
• The problems of floods and drought will get solved as excess water from an area can be transferred to water deficit areas.
• The inland waterway transportation will improve which will make the transportation of materials across the country easier.
• It will also help in imporving irrigational facilities which will increase the productivity.dro-electricity and fisheries activities.

Q3. Write three characteristics of the Peninsular river.

Answer

Three characteristics of the Peninsular river are:
• These rivers originate in Peninsular plateau and central highland.
• These are seasonal and dependent on monsoon rainfall.
• These rivers are smaller having fixed course with well adjusted valleys.

Q4. What are the important characteristic features of north Indian rivers? How are these different from Peninsular rivers?

Answer

The important characteristic features of north Indian rivers are:
• They originate in Himalayan mountain covered with glaciers.
• These rivers are perennial in nature because they receive water from glacier and rainfall.
• These rivers form deep gorges and V-shaped valleys in mountainous areas.
• It has long course, flowing through the rugged mountains experiencing headward erosion and river capturing.
• These rivers are young and youthful, active and deepening in the valleys.

These are different from peninsular rivers because of these reasons:
• The north Indian rivers have very large basins while peninsular rivers have relatively smaller basin.
• The north Indian rivers are perennial as they receive water from glaciers and rainfall while peninsular rivers receive their water only from monsoon rains.
• The north Indian rivers are antecedent and consequent leading to dendritic pattern in plains while peninsular rivers are super imposed, rejuvenated resulting in trellis, radial and rectangular patterns.
• The north Indian rivers are young and youthful, active and deepening in the valleys while peninsular rivers are old with graded profile, and have almost reached their base levels.

Q5.Suppose you are travelling from Haridwar to Siliguri along the foothills of the Himalayas. Name the important rivers you will come across. Describe the characteristics of any one of them.

Answer

If we are travelling from Haridwar to Siliguri along the foothills of the Himalayas we will come across Gomti, Ramganga, Rapti, Gandak, Kosi, Kamla, Saryu, Sharda, Ghaghra, Mahanadi and Ganga.
The characteristics of Gandak:
• It rises in the Nepal Himalayas between the Dhaulagiri and Mount Everest and drains the central part of Nepal
• It comprises two streams, namely Kaligandak and Trishulganga
• It enters the Ganga plain in Champaran district of Bihar and joins the Ganga at Sonpur near Patna.
• Its length is 630 Km.

Long Answer Type Questions:

Q1.How are rivers of India useful for India?
Answer:
Rivers are useful for us because:

• Water: Rivers carry water and nutrients to areas all around the earth. They play a very important part in the water cycle, acting as drainage channels for surface water. Rivers drain nearly 75% of the earth’s land surface.
• Habitats: Rivers provide excellent habitat and food for many of the earth’s organisms. Many rare plants and trees grow by rivers. Ducks, voles, otters and beavers make their homes on the river banks. Reeds and other plants like bulrushes grow along the river banks. Other animals use the river for food and drink. Birds such as kingfishers eat small fish from the river.
• Delta: River deltas have many different species of wildlife. Insects, mammals and birds use the delta for their homes and for food.
• Transport: Rivers provide travel routes for exploration, commerce and recreation.

Q2.Explain about Indus River System.
Answer:
The Indus System

• It is one of the largest river basins of the world, covering an area of 11,65,000 sq. km (in India it is 321, 289 sq. km) and a total length of 2,880 km (in India 1,114 km). The Indus also known as the Sindhu, is the westernmost of the Himalayan rivers in India.
• It originates from a glacier near Bokhar Chu (31°15′ N latitude and 81°40′ E longitude) in the Tibetan region at an altitude of 4,164 m in the Kailash mountain range.
• The Indus receives a number of Himalayan tributaries such as the Shyok, the Gilgit, the Zaskar, the Hunza, the Nubra, the Shigar, the Gasting and the Dras. It finally emerges out of the hills near Attock where it receives the Kabul river on its right bank. The other important tributaries joining the right bank of the Indus are the Khurram, the Tochi, the Gomal, the Viboa and the Sangar.
• They all originate in the Sulaiman ranges. The river flows southward and receives ‘Panjnad’ a little above Mithankot. The Panjnad is the name given to the five rivers of Punjab, namely the Satluj, the Beas, the Ravi, the Chenab and the Jhelum.
• It finally discharges into the Arabian Sea, east of Karachi.
• The Indus flows in India only through the Leh district in Jammu and Kashmir.

Q3.Explain about Ganga River System.
Answer:

The Ganga System:

1. The Ganga is the most important river of India both from the point of view of its basin and cultural significance. It rises in the Gangotri glacier near Gaumukh (3,900 m) in the Uttarkashi district of Uttarakhand. Here, it is known as the Bhagirathi. It cuts through the Central
and the Lesser Himalayas in narrow gorges.

2.  At Devaprayag, the Bhagirathi meets the Alaknanda; hereafter, it is known as the Ganga. The Alaknanda has its source in the Satopanth glacier above Badrinath. The Alaknanda consists of the Dhauli and the Vishnu Ganga which meet at Joshimath or Vishnu Prayag.

3. The river has a length of 2,525 km. It is shared by Uttarakhand (110 km) and Uttar Pradesh (1,450 km), Bihar (445 km) and West Bengal (520 km). The Ganga basin covers about 8.6 lakh sq. km area in India alone.

4. The Ganga river system is the largest in India having a number of perennial and non-perennial rivers originating in the Himalayas in the north and the Peninsula in the south, respectively. The Son is its major right bank tributary.

5. The important left bank tributaries are the Ramganga, the Gomati, the Ghaghara, the Gandak, the Kosi and the Mahananda. The Yamuna, the westernmost and the longest tributary of the Ganga, has its source in the Yamunotri glacier on the western slopes of Banderpunch range (6,316 km).

6. The river finally discharges itself into the Bay of Bengal near the Sagar Island.

Q4.What factors determine volume of water in a river?
Answer:
Factors affecting the volume of water in a river:

1. An important factor affecting the volume of water in a river is the size of the drainage basin. A drainage basin in an area drained by one main river and its tributaries. If the drainage basin is large, the volume of water in the river will be more. When the drainage basin is large the surface run off flourished the river is more runoff in the amount of rainwater that flows on the ground and ultimately into the river or lake. On the other hand, if the drainage basin is small volume of water in the river will be less because there is less surface area for the rain to fall on.

2.Vegetation is also an important factor. Leaves of tress intercept rainwater and allow more water to sweep into the ground in groundwater. As a result, the amount of surface runoff reduces. Therefore, the volume of water in the river is less where vegetation is dense. Spare vegetation prevents rainwater from getting trapped in the leaves and
branches, thereby allowing more water to flow through as surface runoff. So, in areas with less vegetation volume of water is more.

3. Permeability of rocks: In area with permeable or porous rocks, much of the rainwater sweeps through the pores in the rocks into the ground. In such areas, surface run off is less and water flowing into the river channel will also be less.

4. Climate: In areas with hot and wet climate such as equatorial area, volume of water rivers will be high. However, the amount of water will be less in areas with dry climate receiving less rainfall. In areas with prominent wet or dry seasons, volume of water in the river will vary according to the amount of rainfall received.

Q5.Explain the different drainage patterns formed by rivers. Draw diagram of each drainage pattern with two examples of each.
Answer:
The drainage pattern formed by rivers are:
(a) Dendritic:
The drainage resembling, the branches of a tree is known as ‘dendritic’ the examples of which are the rivers of northern plains like Ganga, Yamuna, etc.

(b) Radial: When the rivers originate from a hill and flow in all directions, the drainage pattern is known as ‘radial’ or the dome-shaped pattern. The river originating from the Amarkanta range and central highlands present a good example of it.

(c) Trellis: When the primary tributaries of rivers flow parallel to each and secondary tributaries join them at right angles, the pattern is known as ‘trellis’ e.g. Peninsular river such as Godavari, Krishna etc.

(d)Centripetal: When the rivers discharge their waters from all directions in a lake or in depressions, it is known as ‘centrifugal’. These rivers form cascades/rapids and waterfalls.

Q6.Differentiate between:
(a) Himalayas rivers and the Peninsular rivers.
Answer:
Difference between Himalayas Rivers and the Peninsular rivers.

Aspects	Himalayan rivers	Peninsular rivers
Place of origin	Himalayan mountains covered with glaciers	Peninsular plateau and central highland
Nature of flow	Perennial; receive water from glacier and rainfall	Seasonal, dependent on monsoon rainfall
Type of drainage	Antecedent and consequent leading to dendritic pattern in plains.	Super imposed : rejuvenated resulting in trellis and rectangular pattern
Nature of river	Long course, flowing through the mountains. Experiencing headwater erosion and river capturing in plains meandering and shifting of course.	Smaller, fixed course with well adjusted valleys.
Catchment area	Very large basins	Relatively smaller basin
Area of river	Young and youthful, active and deepening of the valleys.	Old rivers with graded profile, and have almost reached their base levels
Examples	Indus, Ganges and Brahmaputra and their tributaries.	Peninsular Plateau Chambal, Betwa, Central Highlands, Godavari, Krishna, etc.

(b) Consequent rivers and Antecedent rivers
Answer:
Difference between Consequent rivers and Antecedent rivers

Basis	Consequent rivers	Antecedent rivers
Shape	These rivers maintain their original shapes, deposits, the rise of land due to folding. The rivers keep on following in the same direction.	It is an uplift area the rivers flow in the direction resulting as consequent of the slope
Age	These rivers are older than the old mountain.	These rivers are formed after the uplift of an area.

Gorges	These rivers cut deep gorges due to down cutting.	These rivers do not form gorges.
Examples	Trans- Himalayan rivers such as Indus, Satluj, represent consequent rivers.	The eastward flowing river of peninsular plateau which flow according to the slope are antecedent rivers.

Q7.Differentiate between canyon, gorge and river valley.
Answer:
A canyon is a deep valley with steep sides, think of the grand canyon most famously to visualise what this is. A gorge is a deep ravine, which usually has a river running through it—though this doesn’t have to be the case. Finally a valley is any depression, usually of a certain length, in the surface of the land and often contains a river. So, a canyon is a specific type of valley, with particularly steep sides. A gorge is a particularly deep depression, and will usually contain a river.

SHORT ANSWER TYPE QUESTION:

Q1.If a person is to travel to Lakshadweep, from which coastal plain does he prefer and why?
Answer
The person will prefer to travel from the western coastal plains because the Lakshdweep islands are situated in Arabian Sea which distance is lowest from this coast. Therefore, it will take the least time to reach the Lakshadweep.

Q2. Where in India will you find a cold desert? Name some important ranges of this region.

Answer

The cold desert in India is located in the north eastern part of the Kashmir Himalayas, which lies between the Greater Himalayas and the Karakoram ranges.

Q3.Why is the western coastal plain is devoid of any delta?

Answer

The western coastal plains are narrow and have steep slope. The rivers flow rapidly in one part and hence they don’t form any deltas. Therefore, the western coastal plain is devoid of any delta.

Q4.Make a comparison of the island groups of the Arabian Sea and the Bay of Bengal.

Answer

Island groups of the Arabian Sea	Island groups of the Bay of Bengal
This island group consists of about 36 islands of which 11 are inhabited.	This island groups consist of about 572 islands/islets.
These are situated between 8°N-12°N and 71°E -74°E longitude.	These are situated roughly between 6°N-14°N and 92°E -94°E.
The entire group of islands is broadly divided by the Eleventh degree channel, north of which is the Amini Island and to the south of the Canannore Island.	The entire group of island is divided into two broad categories – the Andaman in the north and the Nicobar in the south.
The entire island group is built of coral deposits.	These islands are an elevated portion of submarine mountains.
Minicoy is the largest island with an area of 453 sq. km.	The two principal groups of islands include the Ritchie’s archipelago and the Labrynth island.

Q5.What are the important geomorphological features found in the river valley plains?

Answer

The river valley plains are formed by the alluvial deposits brought by the rivers. The important geomorphological features found in the river valley plains are:

• Bhabar is a narrow belt ranging between 8-10 km parallel to the Shiwalik foothills at the break-up of the slope.

• Terai: South of the Bhabar is the Tarai belt, with an approximate width of 10-20 km where most of the streams and rivers re-emerge without having any properly demarcated channel, thereby, creating marshy and swampy conditions known as the Tarai.
→ This has a luxurious growth of natural vegetation and houses a varied wild life.

• Bhangar: It is composed of old alluvium. These areas are less prone to flooding and less fertile as well.

• Khadar: It is composed of new alluvial deposits. These areas are prone to flooding and are very fertile

• Delta:  A river delta is a landform that occurs at the mouth of a river near where the river flows into the ocean. For example, the famous Sunderbans delta.

Q6. If you move from Badrinath to Sunderbans delta along the course of the river Ganga, what major geomorphological features will you come across?

Answer

Badrinath is situated along Ganga river. The Sunderban delta is on the mouth of Ganga and Brahmaputra in Bay of Bengal. If we are moving from Badrinath to Sunderbans delta along the course of the river Ganga, we will come across various of geomorphological features. As we start moving we will come across gorges, V-shaped valleys, rapids, waterfalls, etc. We will also see places where tributaries meet main river Ganga. After sometime, we will enter into northern plains. We will see various erosional and depositional landforms such as sand bars, meanders, oxbow lakes and braided channels. At last, we will reach our destination, swampy and marshy area known as Sunderbans delta formed by the Ganga and Brahmaputra river.

Long Answer Type Questions:

Q1.Write a detailed on Kashmir or north-western Himalayas.
Answer:
Kashmir or North-western Himalayas:

• Region extents over Jammu and Kashmir, Himachal Pradesh and Uttaranchal.
• It comprises of Ladakh, Zaskar and Pir Panjal.
• The north-eastern parts of Kashmir Himalayas is a cold desert which lies between greater Himalayas and Karakoram ranges.
•  Between Pir Panjal and Great Himalayas in Dal Lake and Valley of Kashmir.
• Important Glaciers here are:
  • Siachen
  • Baltora
  • Babura
  • Hispar.
• Kashmir valleys are known for Karewas. Karewas are thick deposits of glacial clay and other material embedded with moraines (Zafran-Saffron is cultivated here):
• Important passes: Zoji La on the Great Himalayas, Banihal on Pir Panjal range, Photu La-Zaskar range, Kharaung La on Ladakh range. Thadala, Nitila, Lepulekh in Uttaranchal Nathula in Sikkim in Himachal Pradesh.
• Himalayas are spread between river Indus to river Mahi. The total extent of western Himalayas is 700 km and 400 km in width.
• Kashmir Himalayas, Punjab Himalayas and Kumaon Himalayas are its sub¬division.
• The important lakes are: Dal lake and Wular lake (in Jammu and Kashmir and they are freshwater lakes), Pangong Tso, Tso Moriri ( they are salt water lakes and they are situated in Jammu and Kashmir.
• Important rivers: Indus, Jhelum and Chenab.
• Important pilgrimages Vaishno Devi, Amaranth and Charar-e-Sharif.
• The southernmost part of the region has longitudinal valleys known as Duns, e.g. Jammu Dun and Pathankot Dun.

Q2.Explain the characteristics or features of Northern plains?
Answer:
The Northern Plains-

• These plains extend approximately 3,200 from the east to the west.
• The average width of these plains varies between 150-300 km.
• The maximum depth of alluvium deposits varies between 1,000-2,000 m.
• The area covered by northern plains is 7 lakhs square km and is most densely populated region of country.
  From north to South, these plains can be divided into three sub divisions: Bhabar, Tarai and Alluvial Plains. The alluvial plains can be further divided into the Khadar and the Bhangar.

Bhabar

• It is a narrow belt ranging between 8-16 km parallel to the Shiwalik foothills at the breaking of the slopes.
• The streams and rivers coming from the mountain deposit heavy materials of rocks and boulders and at times, disappear in this zone.

Tarai

• Its approximate width is of 20-30 km where most of the streams and river re-emerge without having any properly demarcated channel, thereby, creating marshy and swampy condition known as the Tarai.
• It has a luxurious growth of natural vegetation and houses a varied wild life.

Alluvial Plains

• These plains have characteristic features of mature stage of fluvial erosional and depositional landforms such as sand bars, meanders, ox- bow lakes and braided channels. The Brahmaputra plains are known for their riverine islands and sand bars.
• The mouths of these mighty rivers also form some of the largest deltas of the world, for example, the famous Sunderbans delta.
• These river valley plains have a fertile alluvial soil cover which supports a variety of crops like wheat, rice, sugarcane and jute, and hence supports a large population.

Q3.Explain the physical features of coastal plains.
Answer:
On the basis of the location and active geomorphological processes, it can be broadly divided into two:

• The western coastal plains;
• The eastern coastal plains.

The western coastal plains are an example of submerged coastal plain. It is a narrow belt and provides natural conditions for the development of ports and harbours. Kandla, Mazagaon, JLN port. Navha Sheva, Marmagao, Mangalore, Cochin, etc. are some of the important natural ports located along the west coast.

Extending from the Gujarat coast in the north to the Kerala coast in the south, the western coast may be divided into following divisions – the Kachchh and Kathiawar coast in Gujarat, Konkan coast in Maharashtra, Goan coast and Malabar coast in Karnataka and Kerala respectively. As compared to the western coastal plain, the eastern coastal plain is broader and is an example of an emergent coast.

There are well- developed deltas here, formed by the rivers flowing eastward in to the Bay of Bengal. These include the deltas of the Mahanadi, the Godavari, the Krishna and the Kaveri. Because of its emergent nature, it has less number of ports and harbours. The continental shelf extends up to 500 km into the sea, which makes it difficult for the development of good ports and harbours.

It is believed that the city of Dwaraka which was once a part of the Indian mainland situated along the west coast is submerged under water. Because of this submergence it is a narrow belt and provides natural conditions for the development of ports and harbours. Kandla, Mazagaon, JLN port Navha Sheva, Marmagao, Mangalore, Cochin, etc. are some of the important natural ports located along the west coast.

Q4.How are Arunachal, Himachal, Purvachal and Uttaranchal Himalayas different from each other?
Answer
Arunachal Himalayas

• These extend from east of Bhutan to Diphu pass in East.
• Important peaks are- Kangtu and Namcha Barwa.
• They are bisected by fast flowing rivers forming deep gorges.
• Brahmaputra flows through deep a gorge after crossing Namcha Barwa.
• Subansiri, Dihang, Dibang and Lohit are the important rivers. Perennial rivers have high rate of fall which helps to generate hydro-electricity.

The Himachal and Uttarakhand Himalayas-

• It lies between river Ravi and Kali in the east.
• Northernmost part is the extension of the Ladakh desert.
• All these ranges Nimadi, Himachal and Chivalric are prominent here.
• Hill stations are Dharamshala, Mussoorie, Shimla, Ranikhet and Almora.
• Shiwaliks are important for dun formation. For example- Kalka dun, Nalagarh dun (Dehradun is the largest- dun, its length is 35-45 km and width is 22-25 km.)
• Tribes common are Dhotia’s which migrates to higher region in summer.
• Valley of flowers- Nanda devi is also situated here.
• Gail’s, the Manipur Pilgrimages common are Kedarnath, Badrinath, Hemkund Sahib.

The Eastern Hills and mountains or Purvachal.

• General alignment from the north to south direction.
• In north, they are known as Patkai Bum, Naga hills, the Manipur hills and in the south, as Mizo or Lushai Hills. This forms Purvanchal range.
• Most of these ranges are separated from each other by numerous small rivers.
• The barak is an important river in Manipur and Mizoram.
• Mizoram has a large lake known as ‘loktak lake is made up of soft unconsolidated deposits.
• Mizoram and Manipur are tributary of Barak river, which is the turn tributary of Meghna rivers in eastern part of Manipur are tributaries of Chindwin which is in turn is a tributary of Ireawady of Myanmar.

Q5.Differentiate between:
(i) Bhabar and Tarai
Answer:
Difference between Bhabar and Tarai.

Bhabar	Basis	Tarai
It lies along the foot of shiwalik from Indus to Tista	Location	It lies to the south of Bhabar and runs parallel to it.
It is 8 to 16 km wide.	Width	It is 20-30 km wide.
It comprises of pebbles studded rocks in the shape of porous bed.	Composition	It is composed of firmer alluvial particles and is covered by forests.
Due to the porousity of rocks the stream disappear and flow underground.	Appearance	The underground streams of Bhabar reappear here giving rise to a wet marshian.
It is not suitable for agriculture.	Suitability	It is reclaimed for agriculture purpose.

(ii) Bhangar and Khadar
Answer:
Difference between Bhangar and Khadar

Bhangar	Basis	Khadar
It is a highland composed of old alluvium.	Composition	It’s a lowland composed of new alluvium.
It is always above the level of flood plains.	Flood	It is flooded almost every year.
It comprises of canvanious nodules	Fertility	It comprises of clay soil which is normally fertile
It is not much suited for agriculture.	Suitability	It is suited for agriculture. Intensive agriculture is practiced.
It is known as dhaya in Punjab.	Other name	It is known as bate in Punjab.

(iii) Western Ghats and Eastern Ghats
Answer:
Difference between Western Ghats and Eastern Ghats;

Western Ghats	Basis	Eastern Ghats
They form continuous chain from Gulf of Combay to Kanniyakumari.	Location	They form a discontinuous chain of low hills from Odisha to Coromandel coast.
They are having an elevation of 900-1100m.	Peaks	They are denuded peaks and have lesser elevation than 900 km.
They are divided as four regions or the four hills Sahyadri hills in Maharashtra, Nilgiri in Karnataka and Tamil Nadu, Anaimalai hills and Cardamom hills in Kerala.	Hills	Some of the important ranges include the Javadi hills, the Palconda range, the Nallamala hills, the Mahendragiri hills, etc.
The western ghats get southward monsoon.	Rainfall	The eastern ghat gets rainfall from north-east monsoon.
The highest peak in western ghat is Anamudi (2695 m)	Highest Peak	Highest peak of eastern ghat is Mahendragiri (1501 m)
The height of the mountain increases from north to south.	Change in height	Height increases from south to north.
The westward flowing river are Narmada and Tapi.	Rivers	Eastward flowing rivers are Godavari Krishna, Kaveri, Mahanadi, etc.

(iv) Peninsular Plateau and Indo-Gangetic Plateau
Answer:
Difference between Peninsular Plateau and Indo-Gangetic Plateau

Peninsular Plateau	Basis	Indo-Gangnetic Plateau
It is triangular plateau bounded by Vindhyas western ghats, and eastern ghats.	Stretch	It is alluvial plain stretching from Punjab to Assam valley.
The relief of this plateau is uneven. Its average height is more than 600 m above the sea level.	Level	This is a level plain for about 200 m in height above the sea level.
The climate is hot and humid.	Climate	The summers are hot and winters are cold.
Kaveri, Krishna, Godavari, Mahanadi, Narmada, Tapi are seasonal rivers.	Rivers	Ganga, Yamuna, Brahmaputra are perennial rivers.
Area has black soil.	Soil	Alluvial soil is found.
Known as storehouse of minerals and important for industries.	Known for	Known for agriculture and provide employment to people.

(v) Western Coastal Plains and Eastern Coastal Plains
Answer:
Difference between Western Coastal Plains and Eastern Coastal Plains

Western coastal plain	Basis	Eastern coastal plain
They lie between western ghats and Arabian sea.	Location	They lie between eastern ghats and bay of Bengal.
They are narrow alluvial plain which are separate by hilly terrains.	Width	They are wider plain (80-120 km) with well developed deltas of the rivers.
The western coastal plains are further divided into two parts: Konkan coast, Malabar coast	Furtherclassification	They are further divided as northern circus and Coromandel coast.
They are known for lagoons estuary and kayals (backwater), which are known for fishing and Inland transportation.	Known For	They are known for deltas formed by the rivers and is more suitable for agriculture.
They receive rainfall from south­west monsoons.	Rainfall	They receive rainfall by retreating or north-west monsoon.
The important rivers are Narmada, Tapi	Rivers	The important rivers are Krishna, Kaveri, Mahanadi, etc.
They are submerged coast.	Merging	They are emergent coast.

(vi) Northern Plains and Coastal Plains
Answer:
Difference between Northern Plains and Coastal Plains

Northern Plains	Basis	Coastal Plains
They are located on foot hills of Himalayas and above peninsular plateau.	Location	They lie between Arabian Sea, Western Ghats and Eastern Ghats and Bay of Bengal.
They spread between the area of 3200 square km and the width is 240-320 km.	Stretch	They are spread from Gujarat to Kanniyakumari and Odisha to Kanniyakumari.
Rivers originating from Himalayas and peninsular plateau has form these plains by depositing sediments brought by rivers.	Rivers	Most of the rivers originating from peninsular plateau like Krishna, Kaveri, Godavari, Mahanadi move eastward and form delta whereas Narmada and Tapi move westward from Estuaries.
Due to fertile alluvial soil and water supply they are known for agriculture.	Suitability	They are drained by perinial rivers and are important for fishing, lagoons, and harbours.
They are divided as Indus plains, Ganga plains and Brahmaputra plains.	Divisions	They are divided as Konkan coast and Malabar coast, Northern Circar on eastern side and Coromandel coast.
They are important for riverine features like natural leaves, sand bars, etc.	Known for	They are important for ports, harbours, kayals and backwaters.

(vii) Himalayas and Central Highlands
Answer:
Difference between Himalayas and Central Highlands

Himalayas	Basis	Central Highlands
They are the young fold mountains of comparatively recent origin.	Young vs. Old	They are part of oldest structure of Indian subcontinents.
They are the world’s highest mountains and the Mount Everest is the highest peak of the world.	Height	They are formed of low hills and no high peak is there worth mentioning in the area.
The mighty rivers like Indus, Ganga, Brahmaputra originate beyond the Himalayas.	Rivers	Quite a few rivers like Tapi, Chambal, Betwa, Narmada, originate from these highland.
They are made up of sedimentary rocks.	Composition	They are formed by Igneous and metamorphic rocks.
They are formed at the edge of northern plains.	Location	They are formed at the edge of Deccan Plateau.
Important hill stations are Srinagar, Shimla, Dhalauzi, Dharamshala, Mussoorie, etc.	Hill stations	They are no well-known hill stations.
Himalayas are known for glaciers and perennial rivers.	Glaciers and rivers	No glaciers and non- perennial river are there.
They have beautiful passes and river valleys.	Scenicbeauty	They are low-lying hills with less common features.

SHORT ANSWER TYPE QUESTION:

Q1. Does India need to have more than one standard time? If yes, why do you think so?
Answer
Yes, as per my thinking India need to have more than one standard time because there is a time gap of about 2 hours between the easternmost parts to westernmost parts of the country. The longitudinal extent of India is large i.e., 30° approximately. Therefore, we need to more than one time zones. There are some countries where there is more than one standard meridian due to their vast east-to-west extent. For example, the USA has seven time zones.

Q2. What are the implications of India having a long coastline?

Answer

Peninsular part of India extends towards the Indian Ocean. This has provided the country with a coastline of 6,100 km in the mainland and 7,517 km in the entire geographical coast of the mainland plus the island groups Andaman and Nicobar and the Lakshadweep. This helps India in establishing close contact with West Asia, Africa and Europe from the western coast and with Southeast and East Asia from the eastern coast. However, it also forces India to have regular monitoring of coastline for the protection from external forces.

Q3. How is the latitudinal spread of India advantageous to her?

Answer

The latitudinal spread of India advantageous to her in many ways:
• The southern part of the country lies within the tropics and the northern part lies in the sub-tropical zone or the warm temperate zone.
• This is responsible for large variations in land forms, climate, soil types and natural vegetation in the country

Q4.While the sun rises earlier in the east, say Nagaland and also sets earlier, how do the watches at Kohima and New Delhi show the same time?

Answer

India follows one standard time for the whole country. 82°30′ E has been selected as the ‘standard meridian’ of India. Indian Standard Time is ahead of Greenwich Mean Time by 5 hours and 30 minutes. Therefore, while in Nagaland sun rises earlier and also sets earlier, but the watches at Kohima and New Delhi show the same time.

Long Answer Type Questions :

Q1.Size of India has endowed India with unique physical diversity. Substantiate.
Answer:
The size of India has endowed her with great physical diversity. The presence of lofty mountains in the north; large rivers such as Ganga, Brahmaputra, Mahanadi, Krishna, Godavari and Kaveri; green forested hills in the north-east and south India; and the vast sandy expanse of Marusthali is very impressive. It is bounded by the Himalayas in the north, Hindukush and Sulaiman ranges in the north-west, Purvachal hills in the north-east and by the large expanse of the Indian ocean in the south. The Himalayas, together with other ranges, have acted as a formidable physical barrier in the past. Except for a few mountain passes such as the Khyber, the Bolan, the Shipkila, the Nathula, the Bomdila, etc. it was difficult to cross it.

It has contributed towards the evolving of a unique regional identity of the Indian subcontinent. Peninsular part of India extends towards the Indian Ocean. This has provided the country with a coastline of 6,100 km in the mainland and 7,517 km in the entire geographical coast of the mainland plus the island groups Andaman and Nicobar located in the Bay of Bengal and the Lakshadweep in the Arabian Sea. Thus India, as a country, is a physically diverse land providing occurrence of varied resources.

Q2.Explain in detail about size and extension of India.
Answer:
Total area of India republic is 32,87,263 sq. Km. From the point of view of area, India is seventh largest country of the world. Its population is 1210 million and it has second position in the world after china from population point of view. The mainland of India, extends from Kashmir in the north to Kanniyakumari in the south and Arunachal Pradesh in the east to Gujarat in the west. India extends from territorial limit further extends towards the sea upto 12 nautical miles (about 21.9 km) from the coast. India lies entirely in the Northern hemisphere. The mainland extends between latitudes 8 4′ N (Kanniyakumari, Cape Caverian) and 37 6′ N ( Indira col, Jammu and Kashmir) and longitudes 68 7′ E (Dwarka, Gujarat) and 97 25′ E (Sadiya, Arunachal Pradesh).

Longitudinal extent of India is 68 7′ to 97 25′ E -(29 ). India’s land length is 15,200 km and it has a coastline of 6,100 km in the mainland and 7,517 km in the entire geographical coast of the mainland plus the island groups Andaman and Nicobar located in the Bay of Bengal and the Lakshadweep in the Arabian Sea Thus India, as a country, is a physically diverse land providing occurrence of varied resources. India is located in the south-central part of the continent of Asia, bordering the Indian Ocean and its two arms extending in the form of Bay of Bengal and the Arabian Sea. This maritime location of Peninsular India has provided links to its neighbouring regions through the sea and air routes.

Q3.Differentiate the following:
(a) Gulf and Strait
(b) Gulf and Bay
Answer:

(a) Gulf and strait are two terms that are often discussed when it comes to geography. As gulfs and straits are both common features in seafaring. It is easy to confuse these two words. However, each feature has their own unique characteristics which in turn give them a unique purpose in the history of mankind.

• Meaning: A gulf is a large body of water almost encircled by land except for a small mouth that opens out to the sea. A strait is a strip of water that separates two lands or two large bodies of water.
• Use: Straits are used for navigational purposes and have played an integral part when it comes to shipping routes. Gulfs are more useful for human settlements, as such areas provide easy access to the ocean while being well protected as well.
• Association: Gulfs can be easily associated with inland bodies of water as well as the ocean. Straits are mostly discussed with regards to the ocean.

(b) Difference between Gulf and Bay

• A bay is not as enclosed by land masses as a gulf.
• Gulf is formed because of erosion of the rocks as water makes inroads into adjoining land.
• Gulfs take any form while bays are mostly oval or round shaped.

SHORT ANSWER TYPE QUESTION:

Q1. What is biodiversity?

Answer

Biodiversity refers to the varieties of plants, animals and micro-organisms, the genes they contain and the ecosystems they form.

Q2.What are the different levels of biodiversity?

Answer

There are three different levels of biodiversity:
• Genetic diversity: It refers to the variation of genes within species.
• Species diversity: It refers to the variety of species.
• Ecosystem diversity: It refers to the number of ecosystems in a certain area.

Q3. What do you understand by ‘hotspots’?

Answer

The areas rich in species diversity are called hotspots of diversity.

Q4. Discuss briefly the importance of animals to human kind.

Answer
Animals capture and store energy, produce and decompose organic materials, help to cycle water and nutrients throughout the ecosystem, fix atmospheric gases and help regulate the climate.

Q5.What do you understand by ‘exotic species’?

Answer

Species which are not the natural inhabitants of the local habitat but are introduced into the system are called exotic species.

Q6.What are the roles played by biodiversity in the shaping of nature?

Answer

Biodiversity has contributed in many ways to the development of human culture and, in turn, human communities have played a major role in shaping the diversity of nature at the genetic, species and ecological levels. Biodiversity plays the following roles:

• Ecological Role of Biodiversity: Species capture and store energy, produce and decompose organic materials, help to cycle water and nutrients throughout the ecosystem, fix atmospheric gases and help regulate the climate. These functions are important for ecosystem function and human survival.

• Economic Role of Biodiversity: Biodiversity is seen as a reservoir of resources to be drawn upon for the manufacture of food, pharmaceutical, and cosmetic products.

• Scientific Role of Biodiversity: Biodiversity also helps in understanding how life functions and the role of each species in sustaining ecosystems of which we are also a species.

Q7. What are the major factors that are responsible for the loss of biodiversity? What steps are needed to prevent them?

Answer

The major factors that are responsible for the loss of biodiversity are:

• Growth in human population has increased the rate of consumption of natural resources which accelerated the loss of species and habitation in different parts of the world.
• Overexploitation of resources and deforestation.
• Destruction of natural habitats.
• Natural calamities such as earthquakes, floods, volcanic eruptions, forest fires, droughts, etc.
• Pesticides and other pollutants such as hydrocarbons and toxic heavy metals.

The steps which are needed to prevent them are:
• Efforts should be made to preserve the species that are endangered.
• Prevention of extinction requires proper planning and management.
• Varieties of food crops, forage plants, timber trees, livestock, animals and their wild relatives should be preserved.
• Each country should identify habitats of wild relatives and ensure their protection.
• Habitats where species feed, breed, rest and nurse their young should be safeguarded and protected.
• International trade in wild plants and animals be regulated.

Long Answer Type Questions:

Q1.In how many categories has the International Union of Conservation of Nature and Natural Resources (IUCN) classified the threatened species of plants and animals?
Answer:
The International Union of Conservation of Nature and Natural Resources (IUCN) has classified the threatened species of plants and animals into three categories for the purpose of their conservation.

• Endangered species: Endangered species includes those species which are in danger of extinction. The IUCN publishes information about endangered species worldwide as the Red List of threatened species.
• Vulnerable species: Vulnerable species includes the species which are likely to be in danger of extinction in near future if the factors threatening to their extinction continue. Survival of these species is not assured as their population has reduced greatly.
• Rare species: Rare species are those species whose population is very small in the world. They are confined to limited areas or thinly scattered over a wider area.

Q2.How do natural calamities and illegal hunting harm biodiversity?
Answer:
Natural Calamities: Natural calamities such as earthquakes, floods, volcanic eruptions, forest fires, droughts, etc. cause damage to the flora and fauna of the earth, bringing change to the biodiversity of respective affected regions. Pesticides and other pollutants such as hydrocarbons and toxic heavy metals destroy the weak and sensitive species. Species which are not the natural inhabitants of the local habitat but are introduced into the system, are called exotic species. There are many examples when a natural biotic community of the ecosystem suffered extensive damage because of the introduction of exotic species. During the last few decades, some animals like tigers, elephants, rhinoceros, crocodiles, minks and birds were hunted mercilessly by poachers for their horn, tusks, hides, etc. It has resulted in the rendering of certain types of organisms as endangered category. Illegal Hunting: Hunting and habitat destruction contributed to a second wave of extinctions after European settlement, including:

• 16 land birds (nine species and seven subspecies).
• One of three native bat species.
• One fish.
• At least 12 invertebrates, such as snails and insects.

SHORT ANSWER TYPE QUESTION:

Q1. What do you understand by the term ‘ecology’?

Answer

Ecology is a scientific study of the interactions of organisms with their physical environment and with each other.

Q2. What is an ecological system? Identify the major types of ecosystems in the world.

Answer

The interactions of a particular group of organisms with abiotic factors within a particular habitat resulting in clearly defined energy flows and material cycles on land, water and air, are called ecological systems.
Ecosystems are of two major types:
• Terrestrial
• Aquatic

Q3.What is a food-chain? Give one example of a grazing food-chain identifying the various levels.

Answer

Thes sequence of eating and being eaten and the resultant transfer of energy from one level to another is known as the food-chain.
Grass (first level) is eaten by deer (intermediate level) is eaten by lion (last level).

Q4. What do you understand by the term ‘food web’? Give examples.

Answer

A network of food chains mixed together to form a food web. For example, a mouse feeding on grain may be eaten by different secondary consumers (carnivores) and these carnivores may be eaten
by other different tertiary consumers (top carnivores). 

Q5. What is a biome?

Answer

A biome is a plant and animal community that covers a large geographical area.

Q6. What are bio-geochemical cycles? Explain how nitrogen is fixed in the atmosphere.

Answer

The balance of the chemical elements is maintained by a cyclic passage through the tissues of plants and animals. The cycle starts by absorbing the chemical elements by the organism and is returned to the air, water and soil through decomposition. These cycles are largely energised by solar insolation. The cyclic movements of chemical elements of the biosphere between the organism and the
environment are referred to as biogeochemical cycles. Bio refers to living organisms and geo to rocks, soil, air and water of the earth.
Ninety per cent of fixed nitrogen is biological. The principal source of free nitrogen is the action of soil micro-organisms and associated plant roots on atmospheric nitrogen found in pore spaces of the soil. Nitrogen can also be fixed in the atmosphere by lightning and cosmic radiation. In the oceans, some marine animals can fix it. 

Q7. What is an ecological balance? Discuss the important measures needed to prevent ecological imbalances.
Answer

Ecological balance is a state of dynamic equilibrium within a community of organisms in a habitat or ecosystem. It can happen when the diversity of the living organisms remains relatively stable.

Ecological imbalances: Ecological balance may be disturbed due to the introduction of new species, natural hazards or human causes.
The important measures to prevent ecological imbalances are:
• By not interfering in nature.
• By controlling population.
• By reusing and recycling things.
• By using natural resources judiciously.
• Afforestation should be encouraged.
Proper knowledge and management are necessary for protecting and conserving the ecosystems.

Long Answer Type Questions

Q1.Explain in detail about carbon cycle.
Answer:
The Carbon Cycle: Carbon is one of the basic elements of all living organisms. It forms the basic constituent of all the organic compounds. The biosphere contains over half a million carbon compounds in them. The carbon cycle is mainly the conversion of carbon dioxide. This conversion is initiated by the fixation of carbon dioxide from the atmosphere through photosynthesis. Such conversion results in the production of carbohydrate, glucose that may be converted to other organic compounds such as sucrose, starch, cellulose, etc. Here, some of the carbohydrates are utilised directly by the plant itself. During this process, more carbon dioxide is generated and is released through its leaves or roots during the day.

The remaining carbohydrates not being utilised by the plant become part of the plant tissue. Plant tissues are either being eaten by the herbivorous animals or get decomposed by the micro- organisms. The herbivores convert some of the consumed carbohydrates into carbon dioxide for release into the air through respiration. The micro-organisms decompose the remaining carbohydrates after the animal dies. The carbohydrates that are decomposed by the micro-organisms then get oxidised into carbon dioxide and are returned to the atmosphere.

Q2.Explain in detail about food chain.
Answer:
Food Chain: This sequence of eating and being eaten and the resultant transfer of energy from one level to another is known as the food-chain. Transfer of energy that occurs during the process of a food chain from one level to another is known as flow of energy. The food- chains get interlocked with one another. This inter- connecting network of species is known as food web. For example, a plant eating beetle feeding on a paddy stalk is eaten by a frog, which is, in turn, eaten by a snake, which is then consumed by a hawk. This sequence of eating and being eaten and the resultant transfer of energy from one level to another is known as the food-chain.

• Producers: The producers include all the green plants, which manufacture their own food through photosynthesis.
• Primary consumers: The primary consumers include herbivorous animals like deer, goats, mice and all plant-eating animals.
• Carnivores: The carnivores include all the flesh-eating animals like snakes, tigers and lions. Certain carnivores that feed also on carnivores are known as top carnivores like hawks and mongooses.
• Decomposers: Decomposers are those that feed on dead organisms (for example, scavengers like vultures and crows), and further breaking down of the dead matter by other decomposing agents like bacteria and various micro-organisms.

Generally, two types of food-chains are recognised: grazing food-chain and detritus food-chain.

• Grazing food chain: In a grazing food- chain, the first level starts with plants as producers and ends with carnivores as consumers at the last level, with the herbivores being at the intermediate level. There is a loss of energy at each level which may be through respiration, excretion or decomposition. The levels involved in a food- chain range between three to five and energy is lost at each level.
• A detritus food-chain: A detritus food chain is based on autotrophs energy capture initiated by grazing animals and involves the decomposition or breaking down of organic wastes and dead matter derived from the grazing food-chain.

Q3.Explain about the working and structure of ecosystem.
Answer:
The structure of an ecosystem involves a description of the available plant and animal species. From a structural point of view, all ecosystems consist of abiotic and biotic factors. Abiotic factors include rainfall, temperature, sunlight, atmospheric humidity, soil conditions, inorganic substances (carbon dioxide, water, nitrogen, calcium, phosphorus, potassium, etc.). Biotic factors include the producers, the consumers (primary, secondary, tertiary) and the decomposers. The producers include all the green plants, which manufacture their own food through photosynthesis.

The primary consumers include herbivorous animals like deer, goat, mice and all plant-eating animals. The carnivores include all the flesh-eating animals like snakes, tigers and lions. Certain carnivores that feed also on carnivores are known as top carnivores like hawks and mongooses. Decomposers are those that feed on dead organisms (for example, scavengers like vultures and crows), and further breaking down of the dead matter by other decomposing agents like bacteria and various micro- organisms.

Q4.Explain in detail about nitrogen cycle.
Answer:
Nitrogen is a major constituent of the atmosphere comprising about seventy- nine per cent of the atmospheric gases. It is also an essential constituent of different organic compounds such as the amino acids, nucleic acids, proteins, vitamins and pigments. Only a few types of organisms like certain species of soil bacteria and blue green algae are capable of utilising it directly in its gaseous form. Generally, nitrogen is usable only . after it is fixed. Ninety percent of fixed nitrogen is biological. The principal source of free nitrogen is the action of soil micro-organisms and associated plant roots on atmospheric nitrogen found in pore spaces of the soil.

Nitrogen can also be fixed in the atmosphere by lightning and cosmic radiation. In the oceans, some marine animals can fix it. After atmospheric nitrogen has been fixed into an available form, green plants can assimilate it. Herbivorous animals feeding on plants, in turn, consume some of it. Dead plants and animals, excretion of nitrogenous wastes are converted into nitrites by the action of bacteria present in the soil. Some bacteria can even convert nitrites into nitrates that can be used again by green plants. There are still other types of bacteria capable of converting nitrates into free nitrogen, a process known as denitrification.

Q5.Explain the features of different forest biomes of the world.
Answer:
Forest biomes are of following types:

1. Tropical Equatorial Forest: Found in 10° N-S
Temp. 20-25°C, evenly distributed Acidic, poor in nutrients Rich in nutrients

2. Tropical Deciduous Forest: Found in 10°-25° N-S
Temp. 25-30°C, Rainfall, ave. ann. 1,000 mm, seasonal

3. Temperate: Found in Eastern North America, N.E. Asia, Western and Central Europe
Temp. 20-30° C, Rainfall evenly distributed 750- 1,500 mm, Well- defined seasons and distinct winter. Fertile, en-riched with decaying litter

4. Boreal: Found in Broad belt of Eurasia and North America (parts of Siberia, Alaska, Canada and Scandinavia).
Short moist moderately warm summers and long cold dry winter; very low temperatures. Precipitation mostly snowfall 400 -1,000 mm.
Acidic and poor in nutrients, thin soil cover.
Rich in nutrients with little or no organic matter.