UPSC 2021 Geography Questions with Answers

Explanation

Statement 1 is correct: In the tropical zone, trade winds blow from the east towards the west. These winds push warm surface water towards the western parts of the oceans (e.g., the western Pacific Ocean and the western Atlantic Ocean). As a result, the water in the western parts of tropical oceans is warmer than in the eastern parts. The eastern sections of the oceans tend to have upwelling, where colder, nutrient-rich waters from deeper layers rise to the surface.

Statement 2 is correct: In the temperate zone, the westerlies (winds blowing from the west towards the east) push the surface water eastward, causing the western parts of oceans (like the western coast of continents) to be colder. The water in the eastern sections of oceans tends to be warmer due to the Ekman transport, which moves warm water towards the eastern coasts. For example, in the North Atlantic Ocean, the Gulf Stream carries warm water from the tropics to the eastern coasts of North America and Europe, keeping the eastern sections warmer than the western parts.

Explanation

Option (d) is correct: The description refers to the Tropical Rainforest or Hot, Wet Equatorial Climate. In this biome, leaf litter decomposes rapidly due to high humidity and temperatures, quickly returning nutrients to the soil. As a result, the soil surface often appears bare with minimal leaf litter. They are home to climbing plants (lianas) and epiphytes (plants that grow on trees), which reach the canopy to access sunlight. These unique plant forms and rapid decomposition are characteristic features of tropical rainforests, making it a highly dynamic and nutrient-efficient ecosystem. Options (a), (b) and (c) are incorrect:

Coniferous forests (or taiga) are characterized by cold climates and slow decomposition rates. The leaf litter in coniferous forests decomposes more slowly than in tropical rainforests due to the lower temperatures and acidic nature of the soil. The description of rapid decomposition and bare soil does not match the characteristics of coniferous forests. Dry deciduous forests experience dry seasons where many trees shed their leaves. While leaf litter does decompose, the process is slower due to the dry conditions. These forests do not have the constant, year-round decomposition found in tropical rainforests. Additionally, the mention of epiphytes and climbing plants is less common in dry deciduous forests. Mangrove forests are coastal ecosystems, typically found in tropical and subtropical regions. They are characterized by salt-tolerant plants and the intertidal zone, not by the rapid de-composition of leaf litter. The soil in mangrove forests is often muddy, and the vegetation is adapted to waterlogged conditions rather than the "bare" soil and climbing plants described in the given statement.

Explanation

Black cotton soil, also known as regur soil, is highly valued in India because of its excellent moisture-retaining properties and suitability for cotton cultivation. Black cotton soil is primarily formed from the weathering of basaltic rocks, which are a type of fissure volcanic rock. These basaltic rocks were originally erupted during the Cretaceous period as part of the Deccan Traps in the northwest Deccan plateau. The weathering process of these volcanic rocks releases minerals that, combined with climatic factors, result in the formation of the distinctive black soil. The high clay content of black cotton soil enables it to retain moisture efficiently. Its properties make it particularly suitable for cotton cultivation, hence the alternative name "black cotton soil."

Explanation

Option (a) is correct: Sugarcane is the least water-ef-ficient crop. It requires around 1800 to 2200 mm of water, making it a water-intensive crop. It has high water requirements, primarily because it is grown in tropical climates where irrigation is essential for optimal growth.

Option (b) is incorrect: Major oilseeds like soyabean, castor seeds, cotton seeds, linseed and sunflower, etc. requires around 672.4 mm of water, which is considerably lower than sugarcane’s water needs, making it more water-efficient.

Option (c) is incorrect: Millets can be grown even in dry regions without irrigation facilities. Pearl millet is a drought-resistant crop that requires only 350 mm of water, making it highly water-efficient, especially in dry regions.

Option (d) is incorrect: Red gram (pulses) requires 200-450 mm of water, making it relatively more water-efficient compared to crops like sugarcane. Crop Water Requirement (mm) Crop Water Requirement (mm) Rice 900-2500 Chillies 500 Wheat 450-650 Sunflower 350-500 Sorghum 450-650 Castor 500 Maize 500-800 Bean 300-500 Sugarcane 1500-2500 Cabbage 380-500 Groundnut 500-700 Pea 350-500 Cotton 700-1300 Banana 1200-2200 Soybean 450-700 Citrus 900-1200 Tobacco 400-600 Pineapple 700-1000 Tomato 600-800 Gingelly 350-400 Potato 500-700 Ragi 400-450 Onion 350-550 Grape 500-1200

Explanation

Option (a) is incorrect: Chenab River originates from Bara Lacha Pass in Himachal Pradesh. It is formed by the confluence of Chandra and Bhaga rivers in Himachal Pradesh, flows through Jammu and Kashmir and enters Pakistan. The Chenab does not join the Indus directly. It merges with the Sutlej River in Pakistan.

Option (b) is incorrect: Jhelum River originates from Verinag Spring in Jammu and Kashmir. It flows through the Kashmir Valley and enters Pakistan. Jhelum joins Chenab, which later merges with Sutlej before reaching the Indus. Jhelum does not directly join Indus.

Option (c) is incorrect: Ravi River originates from Bara Bhan-gal in Himachal Pradesh. It flows through Punjab before entering Pakistan. Ravi joins the Chenab River, which later merges with the Sutlej before meeting the Indus.

Option (d) is correct: Sutlej River originates from Rakshastal, near Lake Mansarovar, Tibet. It flows through Himachal Pradesh and Punjab before entering Pakistan. Sutlej is the only river that directly joins the Indus River at Mithankot, Pakistan. Thus, it is the only Satluj river in the Indus valley system which receives water from three rivers of the system and joins Indus directly. The Indus River System:

Fig: Map of the Indus River System

Explanation

A salt lake or saline lake is a landlocked body of water that has a concentration of salts and other dissolved minerals significantly higher than most lakes. These lakes are characterized by their high salt content, often due to the arid or semi-arid climate and the lack of outflowing rivers leading to the evaporation of water and the concentration of salts. Didwana, Kuchaman, Sargol and Khatu are saline lakes of Rajasthan.

Explanation

Option 1 is incorrect: The Brahmani River does not originate in the Eastern Ghats. The Brahmani River is formed by the confluence of the South Koel and Sankh rivers in Jharkhand. The South Koel originates near Nagri in Jharkhand, while the Sankh River originates in the Chotanagpur Plateau. After the confluence, it flows through the Eastern Ghats in Sundar-garh, Deogarh, Dhenkanal, and Jajpur districts.

Option 2 is correct: The Nagavali River originates in the Eastern Ghats near Lakhbahal in the Kalahandi district of Odisha. It flows through Odisha and Andhra Pradesh before draining into the Bay of Bengal.

Option 3 is incorrect: The Subarnarekha River originates near Nagri in the Chotanagpur Plateau of Jharkhand. It flows through Jharkhand, West Bengal, and Odisha before emptying into the Bay of Bengal. The Chotanagpur Plateau is part of the Deccan Plateau, not the Eastern Ghats.

Option 4 is correct: The Vamsadhara River rises in the Durgakangar Hills of the Eastern Ghats in the Kalahandi district of Odisha. It flows through Odisha and Andhra Pradesh before draining into the Bay of Bengal.