UPSC Prelims 2021 Analysis

Explanation

The vegetation of savannah consists of grassland with scattered small trees. The forest development in such areas is generally kept in check by one or more or a combination of some conditions. These conditions include fire, grazing herbivores, and seasonal rainfall.

Fire is a common occurrence in savannahs and it helps to maintain the grassland by burning out tree saplings.

Grazing herbivores also help to maintain the grassland by eating young tree saplings before they can grow into mature trees.

Seasonal rainfall also plays a role as it affects the growth of trees and grasses.

Burrowing animals and termites, while they do have an impact on the ecosystem, are not the primary factors controlling forest development. Similarly, soil properties can affect the types of vegetation that can grow, but they are not the primary factors controlling forest development in savannahs.

Therefore, the correct answer is (c) 2, 3 and 4.

Savannah Climate:

• It is a transitional climate between equatorial rainforests and hot deserts.
• It has wet and dry seasons like the monsoon climate but with much less rainfall. Unlike the monsoon climate, it lacks a distinct rainy season.
• It has only two seasons—winter and summer, with rain occurring in summer. The savanna landscape features tall grasses and scattered short trees.
• The savanna is called the ‘big game country’ because thousands of animals are hunted or trapped annually by people worldwide.

Explanation

Statement 1 is incorrect. Moringa oleifera, commonly known as the drumstick tree, is a deciduous tree, not an evergreen tree. It sheds its leaves seasonally. Moringa is also a nitrogen-fixing plant, which means it can help restore nutrient balance in the soil by adding nitrogen naturally.

Statement 2 is incorrect. Tamarindus indica is not endemic to South Asia. It is native to tropical Africa and later spread to South Asia and other tropical regions. While tamarind is extensively grown in India, it is also widely cultivated in Southeast Asia, Africa, and the Americas.

Statement 3 is correct. Tamarind is widely collected as minor forest produce by local communities and forest dwellers in many parts of India, especially in states like Madhya Pradesh, Chhattisgarh, Odisha, and Jharkhand.

Statement 4 is correct. India exports tamarind to various countries, especially in Southeast Asia, the Middle East, and Europe. Moringa seeds are also exported due to their high medicinal and industrial value.

Statement 5 is correct. Moringa seeds have a high oil content, which can be processed into biodiesel. Tamarind seeds contain hydrocarbons and polysaccharides that can also be explored for biofuel production.

Explanation

Didwana, Kuchaman, Sargol, and Khatu are the names of saline lakes of Rajasthan.

Explanation

1. Brahmani: This river is formed by the confluence of two rivers, Sankh and Koel, which rise from the Chota Nagpur Plateau and flow through the Eastern Ghats before merging. So, it doesn't originate from the Eastern Ghats itself.

2. Nagavali: The Nagavali River originates in the Eastern Ghats in Odisha and flows through Andhra Pradesh before joining the Bay of Bengal.

3. Subarnarekha: This river originates from the Chota Nagpur Plateau in Jharkhand and flows through Odisha before finally joining the Bay of Bengal. It does not rise from the Eastern Ghats.

4. Vamsadhara: The Vamsadhara River originates from the Eastern Ghats in Andhra Pradesh and flows through Odisha before joining the Bay of Bengal.

Hence, only 2 and 4 are correct.

Explanation

The trade winds in the tropical zone blow from east to west, causing the western sections of the oceans to be warmer than the eastern sections. This is because these winds push the warm surface waters towards the west.

On the other hand, in the temperate zone, the westerlies blow from west to east. These winds push the warm waters towards the eastern sections of the oceans, making them warmer than the western sections.

Therefore, both statements are correct.

Explanation

Option A is incorrect. The Chenab joins Satluj in Pakistan.

Option B is incorrect. The Jhelum joins the Chenab near Jhang in Pakistan.

Option C is incorrect. The Ravi joins the Chenab near Sarai Sidhu.

Option D is correct. Satluj is joined by the Chenab in Pakistan. Thus, Satluj receives the collective drainage of the Ravi, Chenab and Jhelum rivers. It joins the Indus a few kilometres above Mithankot.

Explanation

Tropical Rainforest:

• Hot and moist with year-round rainfall.
• Dense canopy with multiple layers.
• Rapid decomposition due to high temperature and humidity, leaving soil bare.
• Vegetation includes climbers and epiphytes growing on tree branches.
• Different from coniferous, dry deciduous, and mangrove forests.
• Species found in these forests include rosewood, mahogony, aini, ebony, etc.
• Distribution in India: mainly found in the Western Ghats, the Northeastern states, the Andaman & Nicobar Islands, and parts of Odisha's Mahanadi Delta.

Coniferous Forest:

• Found in cold, high-altitude regions.
• Dominated by evergreen trees like pine, fir, spruce, and cedar.
• Needle-like leaves reduce water loss.
• Supports animals like snow leopards, musk deer, and Himalayan black bears.
• Distribution in India: Found in the Himalayan region (Jammu & Kashmir, Himachal Pradesh, Uttarakhand, Arunachal Pradesh, Sikkim).

Dry Deciduous Forest:

• Trees shed leaves in dry seasons to conserve water.
• Dominated by species like teak, sal, neem, and tendu.
• Soil is fertile, making it good for agriculture.
• Home to tigers, deer, elephants, and langurs.
• Distribution in India: Found in central and western India (Madhya Pradesh, Uttar Pradesh, Rajasthan, Maharashtra, Karnataka, Tamil Nadu, Telangana).

Mangrove Forest:

• Grow in coastal, saltwater regions.
• Trees have stilt roots to survive in waterlogged conditions.
• Provide breeding grounds for fish and protect coastlines from erosion.
• Home to species like the Royal Bengal Tiger, saltwater crocodiles, and various birds.
• Distribution in India: Found in coastal regions.

Explanation

• Black soil in India is formed by the weathering of fissure volcanic rock.
• Climatic conditions along with the parent rock material are the important factors for the formation of black soil.
• Black soils are spread mostly across interior Gujarat, Maharashtra, Karnataka, and Madhya Pradesh on the Deccan lava plateau and the Malwa Plateau, where there is both moderate rainfall and underlying basaltic rock.

Brown Forest Soil:

• Develops in temperate forest regions with moderate rainfall.
• It is rich in organic matter, fertile, and well-drained.

Granite and Schist:

• Granite is a hard, igneous rock rich in quartz and feldspar, used in construction.
• Schist is a metamorphic rock with flaky layers, formed under heat and pressure.

Shale and Limestone

• Shale is a fine-grained sedimentary rock, often a source of oil and natural gas.
• Limestone is a sedimentary rock rich in calcium carbonate, used in cement production.

Explanation

Statement 1 is incorrect. When we consider the distribution of water on Earth, we find that the amount of water in rivers and lakes is actually less than the amount of groundwater. This is because groundwater is stored in the Earth's crust, in the pores and spaces between rocks and soil, and it accounts for a significant portion of the Earth's fresh water. On the other hand, rivers and lakes, while visible and important for many ecosystems, actually hold a relatively small amount of the Earth's total water.

Statement 2 is correct. The amount of water in polar ice caps and glaciers is indeed more than the amount of groundwater. This is because these ice caps and glaciers, particularly those in Antarctica and Greenland, hold the majority of the Earth's fresh water.