ISC CLASS 12 GEOGRAPHY
UNIT 1
PHYSICAL ENVIRONMENT OF INDIA
Why is the location of India in the Indian Ocean considered to be significant ? Give two reasons
Answer:-India stands at the head of the Indian Ocean at the very center of the Eastern Hemisphere commanding trade routes running in all directions. It’s location, size and economic resources have made it the most dominating country among the littoral states. It serves as a great linkage between the countries lying on its coasts and further beyond. Thus, the location of India in the Indian Ocean is considered to be significant.
2.With reference to the extent of India, write the angular values of the points marked as (a), (b), (c) and (d) in the map given below :
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Answer:-(a) Western longitude 68° 7′ East.which is in rann of Kutch
(b) Standard Meridian 82° 30′ East.which passes through Mirzapur, Uttar Pradesh.
(c) Eastern Longitude 97° 25′ East.which is in Kithubu (Arunachal Pradesh)
(d) Tropic of cancer 23° 30′ North.
Name the four Indian geological eras in their chronological order.
Answer:- The four Indian geological eras in their chronological order are the Archean era (Early Pre-Cambrian), the Purana era (Late Pre-Cambrian), the Dravidian era (400-570 million years old), and the Aryan era (400 million years old to the present).
Briefly explain any two factors responsible for the depletion of forests in India.
Answer:- Factors responsible for the depletion of forests in India are :
Thoughtless and rapid exploitation of forest resources as per the demand of the increasing population.
For acquiring land for agriculture, industries and construction purposes, the forests have been cut down recklessly.
Mention any two differences between the Bhabar and the Terai regions.
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Briefly explain the geological evolution of the Himalayas. [3
Biefly explain the geological evolution of the Himalayas. [3]
Answer:-The Himalayan ranges were formed when the Indian plate was driven northwards and pushed beneath the Eurasian Plate. With the advance of the Indian Plate towards the north, the Tethys started contracting about 65-70 million years ago. About 30-60 million years ago, the two plates came closer and the Tethys sea crust began to fracture into thrust edges. About 20-30 million years ago, the Himalayan ranges started emerging.
(b) Explain giving any two reasons why the deltas of the river Mahanadi suffer from occasional floods. [2]
Answer:- The deltas of the river Mahanadi suffer from occasional floods because of :
Large scale silting and the consequent change in the river courses.
Indiscriminate felling of trees in the catchment areas of the river has complicated the flood problem.
High tide at the time of flood aggravates the flood situation.
(c) Study the temperature and rainfall graph of station X given below and answer the questions that follow : [3]
(I) Is the location of station X inland or coastal ?
Answer:- Inland
(ii) What is the cause of sudden fall of temperature in July, even though it is a summer month ?
Answer:-The cause of sudden fall of temperature in July is due to the onset of the monsoon season. There is a fall of temperature from July to September because of rainfall during this period.
(iii) Mention one main feature of the climate experienced by the station X.
Answer:- The station experiences continental type of climate with marked seasonal changes with respect to temperature and rainfall.
(d) What is Agro-forestry ? Mention any two benefits of Agro-forestry. [2]
Answer:- Agro forestry involves the raising of trees and agricultural crops either on the same land or in close association in such a way that all land including the waste patches is put to good use. Two benefits of Agro-forestry are :
The farmers are able to get food, fodder, fuel, fruit, and timber from their land.
The land gives maximum production and provides employment to rural masses.
Give two reasons to explain why India is considered to be a subcontinent.
Answer:- :
India is called a subcontinent because of its :
Vast size.
Diversity like : The Thar desert, The icecovered lofty Himalayas in the north, Vast Indo-Gangetic plains to its south, The Deccan plateau, The high temperature and heavy rains of the tropical monsoon climate.
The figure below represents a topographic section from the Himalayas to the Peninsular region. Identify any two of the features marked A, B, C and D.
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Answer:-A – Shivaliks or outer Himalayas.
B – Bhabar.
C – Bhangar.
D – Khadar.
With reference to river Godavari, name the following :
(a) The State where it originates.
(b) The State where it forms its delta.
Answer:-(a) Godavari originates in the Nashik district of Maharashtra.
(b) Godavari forms its delta before joining Bay of Bengal in Andhra Pradesh.
What is urban forestry ? Mention any two of its objectives.
Answer:- Urban forestry pertains to raising and management of trees on public and privately owned lands in and around urban centres. It includes green-belts, road side avenues, parks etc. Its main objectives are :
Reduction of environmental pollution.
Recreation and improving aesthetic values.
(b) Explain the following : [2]
(i) The Himalayan rivers are typical examples of antecedent drainage.
Answer:- Antecedent drainage is a river system originating before a period of uplift and folding of the land as a result of earth movements. The Himalayan rivers like Indus, Satluj and the Brahmaputra continue to cut down their valley at approximately the same rate as the uplift of the land and so maintain the general pattern and direction. So these rivers are known as Antecedent drainage.
(ii) Jaisalmer receives very less rainfall annually.
Answer:- The Aravali’s alignment is parallel to the rain-bearing SW monsoon winds, so Jaisalmer does not receive any rain from the Arabian Sea branch of SW monsoon. It is also located in the rain shadow region of the Bay of Bengal branch of SW monsoon. So it does not receive
any rain from the Bay of Bengal branch too.
(c) Study the climatic data provided in the table below for a city A in India and answer the questions that follow : [2]
T= Mean monthly temperature in degree Celsius (°C).
R = Average monthly rainfall in millimetres (mm).
(i) What is the cause of low rainfall in station A ?
Answer:- Rain shadow region.
(ii) Calculate the range of temperature of this station.
Answer:-(18°C) – (-8°C) = 26°C.
(d) (i) State how rainfall and temperature influence the vegetation type in India. [2]
Answer:-Climate : Rainfall and temperature influence the vegetation to a great extent. In India, regions receiving rainfall over 200 cm with high temperatures have tropical evergreen type of vegetation commonly. Regions with average temperature of 24° C 27°C and rainfall ranging between 150 cm 200 cm have tropical deciduous forests. Regions with moderate rain of 50 cm have thorn and scrub type of vegetation.
(ii) Why are tropical evergreen forests not very important economically ? [1]
Tropical evergreen forests are not very important economically because :
The trees are not found in pure stands thus, commercial exploitation proves to be very expensive.
These are hardwood trees, i.e., they do not float on water.
Its warm and wet climate throughout the year paves way for a thick vegetation so, there is a lack of transport facilities. Thus, these forests do not encourage the exploitation economically.
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Name one country each which forms a frontier with India in the :
(a) North _- China
(b) West_- Pakisthan
(ii) Name any two standard geological eras, along with their duration.
Answer 1. Pre-Cambrian over 570 million years old.
2. Paleozoic (245-570 million years old)
(iii) Mention any two differences between the Western Ghats and the Eastern Ghats
State two objectives of social forestry.
To reduce pressure on the traditional forest areas by developing plantations of fuelwoods, fodder and grasses.
Management and protection of the forests as well as afforestation of barren lands, aimed at helping in environmental social and rural development.
Name any two physical divisions of India and state two characteristic features of each. [4]
Himalayas
It is a young fold mountain of loft, weak and unstable.
Himalayas are tectonic mountains and the rivers are torrential.
It was formed 20 – 30 million years ago, during Tertiary period.
Peninsular Plateau
It is an old landmass of hard rocks.
Most of the rocks are granite and Basalt.
Rivers are slow moving and are of low gradients with shallow river valleys.
It was formed during Precambrian era.
(b) Explain how the following factors affect India’s climate : [2]
(i) Southern Oscillation : The Southern oscillation is a pattern of meteorological changes which are often observed between Indian and Pacific oceans. Whenever the surface level pressure is high over the Pacific Ocean and low over Indian Ocean, the south west monsoons in India tend to be stronger. If the surface level pressure is high over Indian Ocean and high over Pacific Ocean, the southwest monsoon is likely to be weaker.
(ii) Northern Mountain Ranges : The Himalayas and the adjoining mountain ranges protects India from the bitter cold dry winds of Central Asia during winters. The mountains also act as an effective physical barrier for the rain bearing southwest monsoons to cross the northern frontiers of India.
Explain The factors affecting the climate of India
The variables that control the temperature change in the climate of India are climate controls. The major climate controls are six in number. They are briefly discussed below:
Latitude: Since the world is a sphere, not all places receive the same amount of sunlight. As we move from the equator to the poles, the temperature drops.
Altitude: As we climb higher above the surface of the earth, the temperature drops.
Pressure and Wind System: The latitude and altitude of each location affect the pressure and wind system there. As a result, it affects the temperature appropriately.
Proximity to the sea: Due to the distance from the sea, coastal areas are cooler than inland areas. Extreme weather conditions are more prevalent and their effect diminishes as the distance from the ocean increases.
Ocean Currents: The temperature of an area will be lowered by cold ocean currents passing over it while its temperature will be raised by warmer currents.
(c) Study the climatic data provided in the table below for a city A in India and answer the questions that follow : [2]
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T = Mean monthly temperature in degree Celsius (°C).
R = Average monthly rainfall in millimeters (mm).
(i) Mention two main features of the climate experienced by station A.
(ii) Calculate the annual rainfall for station A.
Answer:- Two main features of the climate experienced by station A :
(i) 1. The range of temperature is as high as (39°C – 20°C) = 19°C.
2. The station receives rain from south west monsoon.
(ii) 1552 mm.
(d) Name the major region for the following:
(i) Tropical evergreen forests_—-Tropical evergreen forests are found in Andaman and Nicobar islands, Assam, Meghalaya
(ii) Arid forests_—---Arid forests are found in Rajasthan and Southwest Punjab, Southwest Haryana and parts of Gujarat.
(iii) Mountain forests_—-Mountain forests are found in the hilly ranges of northeast India and the Himalayan parts of West Bengal, Bihar and Uttarakhand.
(iv) Tropical monsoonal forests
Tropical monsoonal forests are found in the north-eastern parts of the peninsula, middle and lower Ganga valley and along the foothills of the Himalayas.
State the latitudinal and longitudinal extent of India.
Answer:- 8°4'N to 37°6'N and 68°7'E to 97°25'E.
(ii) Mention any two characteristic features of the Peninsular Plateau of India.
Answer:- Peninsular Plateau is the oldest landmass of India. General elevation is 600-1000 metres and slopes down to 500 metres in the north. The general slope of this plateau is from west to east.
(iii) The diagram given below represents the Punjab Plain. Study the diagram and answer the questions that follow :
Name any two of the rivers numbered 1, 2,3 and 4.
Answer:- Jhelum , Chenab, Ravi & Beas
Name any two of the five doabs marked A, B, C, D and E.
Answer :- A. Sind Sagar Doab
B. Chaj Doab
C. Rechna Doab
D. Bari Doab
E. Bist Doab
Give any three differences between Eastern Coastal lowland and Western Coastal lowland.
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(b) Study the climatic data provided in the table below for a city A in India and answer the questions that follow :
T = Mean monthly temperature in degree Celsius (°C).
R = Average monthly rainfall in millimetres (mm).
(i) Account for the maximum rainfall in the months of October-November.
(ii) Account for the low rainfall in city A during the months of June to September.
Answer:- Retreating Monsoon and Northeast Monsoon.
(ii) As the city is located in the eastern coast it receives very low rainfall from the Bay of Bengal Branch of Southwest Monsoon as it runs parallel to the coast.
(c) In the Brahmaputra river basin, floods are almost an annual feature. Give two reasons to explain why.
Answer:- The cause of floods in this river basin is heavy rainfall of around 250 cms at the time of rainy season. Besides, due to formation of silt by the river Brahmaputra along with its tributaries, the water cannot pass through and thus floods take place. Along with this, due to earthquakes the water level varies and due to this hindrance in the level of water inundation takes in a lot of areas. Also, landslides occur frequently and the big rock mass which falls, creates a temporary dam. The adjoining areas are covered under water and in course of time it vents due to water pressure resulting in a lot of areas getting flooded.
(d) With reference to Forest Conservation Movement, explain the Chipko Movement. Give the reason for its success. [2]
Answer;- Chipko movement means people sticking to the tree. Chipko movement was a movement that took place to save trees by the people living in the Garhwal Himalaya. Chipko, literally means to stick with their arms spread around the trees trunks in the Garhwal Himalayas. Reasons for Success are : Hundreds of men, women and children clung to the trees when the loggers came to cut the trees. The loggers were challenged to first kill the people and then cut the trees. So, the loggers had to withdraw themselves without cutting the trees..
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