UPSC 2021: Nexus 51—60

Drainage Networks, Marine Circulations, Sustainable Agronomy & Biome Ecology. [Set A]

Question 51

Ecological Agriculture

How is permaculture farming different from conventional chemical farming?

Permaculture farming discourages monocultural practices but in conventional chemical farming, monoculture practices are predominant.
Conventional chemical farming can cause increase in soil salinity but the occurrence of such phenomenon is not observed in permaculture farming.
Conventional chemical farming is easily possible in semi-arid regions but permaculture farming is not so easily possible in such regions.
Practice of mulching is very important in permaculture farming but not necessarily so in conventional chemical farming.

Select the correct answer using the code given below.

Official Verdict: (b) 1, 2 and 4

The Core Concept: Permaculture replicates multi-tiered natural ecosystems, strictly discouraging fragile monocultures (1 is true). Chemical farming triggers soil salinity through chemical inputs and canal irrigation; permaculture enriches organic soil matter, preventing salinization (2 is true). Statement 3 is false: Permaculture was designed precisely to restore drought-prone, degraded, semi-arid drylands using swales and earthworks; it thrives in semi-arid settings. Mulching is a core permaculture pillar to preserve moisture and soil biology (4 is true).

Tethered to: REALM 325: Natural Farming

Question 52

Commercial Commodities

With reference to 'palm oil', consider the following statements:

The palm oil tree is native to Southeast Asia.
The palm oil is a raw material for some industries producing lipstick and perfumes.
The palm oil can be used to produce biodiesel.

Which of the statements given above are correct?

Official Verdict: (b) 2 and 3 only

The Core Concept: The oil palm tree (Elaeis guineensis) is indigenous to the tropical rainforests of West and Central Africa, not Southeast Asia (Indonesia and Malaysia cultivate it as introduced plantation crops; Statement 1 is false). Due to its high melting point and smooth texture, palm oil and its derivatives are primary emollients in lipsticks, soaps, and cosmetic perfumes (2 is true). Palm oil methyl ester is widely used across Southeast Asia to refine commercial biodiesel (3 is true).

Tethered to: REALM 33: Oilseeds

Question 53

River Systems of India

With reference to the Indus river system, of the following four rivers, three of them pour into one of them which joins the Indus direct. Among the following, which one is such river that joins the Indus direct?

(a) Chenab
(b) Jhelum
(c) Ravi
(d) Sutlej

Official Verdict: (d) Sutlej

The Core Concept: In the Punjab river confluence hierarchy: the Jhelum empties into the Chenab near Jhang; the Ravi pours into the Chenab near Sarai Sidhu. Then, the swollen Chenab flows south to join the Sutlej river at Panjnad. It is the mighty Sutlej (carrying the unified waters of all four rivers across Panjnad) that travels directly to pour into the mainstream of the Indus near Mithankot, Pakistan.

Tethered to: REALM 16: Indus River System

Question 54

Inland Drainage & Limnology

With reference to India, Didwana, Kuchaman, Sargol and Khatu are the names of

(a) glaciers
(b) mangrove areas
(c) Ramsar sites
(d) saline lakes

Official Verdict: (d) saline lakes

The Core Concept: Didwana, Kuchaman, Sargol, and Khatu are iconic endorheic saline playa lakes located in the Nagaur and adjoining arid tracts of Rajasthan. These shallow depression basins fill briefly during monsoon rains and undergo rapid evaporation under harsh desert heat, precipitating commercial deposits of sodium chloride and sodium sulfate.

Tethered to: REALM 23: Lakes & Inland Drainage

Question 55

Peninsular Drainage

Consider the following rivers:

Brahmani
Nagavali
Subarnarekha
Vamsadhara

Which of the above rise from the Eastern Ghats?

Official Verdict: (b) 2 and 4

The Core Concept: Origin geomorphology differentiates these streams. Nagavali originates in the Eastern Ghats near Lakhbahal (Kalahandi, Odisha). Vamsadhara originates on the border of Kalahandi and Rayagada in the Eastern Ghats. Conversely, the Subarnarekha rises near Ranchi on the Chota Nagpur Plateau, and the Brahmani forms at the confluence of the Sankh and South Koel rivers near Rourkela, drawing waters from the Chota Nagpur highland, not the Eastern Ghats.

Tethered to: REALM 20: East-Flowing Rivers

Question 56

Deep Ocean Geopolitics

Consider the following statements:

The Global Ocean Commission grants licences for seabed exploration and mining in international waters.
India has received licences for seabed mineral exploration in international waters.
'Rare earth minerals' are present on seafloor in international waters.

Which of the statements given above are correct?

Official Verdict: (b) 2 and 3 only

The Core Concept: Statement 1 is false: Licenses for seabed exploration beyond national jurisdiction are granted exclusively by the International Seabed Authority (ISA), established under UNCLOS; the Global Ocean Commission was merely an independent short-term policy initiative that concluded in 2016. Statement 2 is true: India holds an exclusive ISA license for polymetallic nodules in the Central Indian Ocean Basin and polymetallic sulfides in the Southwest Indian Ridge. Statement 3 is true: Deep-sea nodules and pelagic sediments hold vast concentrations of yttrium and rare earth elements.

Tethered to: REALM 98: Deep Ocean Mission

Question 57

Agricultural Hydrology

Among the following, which one is the least water-efficient crop?

(a) Sugarcane
(b) Sunflower
(c) Pearl millet
(d) Red gram

Official Verdict: (a) Sugarcane

The Core Concept: Water efficiency measures the economic yield produced per unit of water consumed. Sugarcane is an ultra-long-duration crop (taking 12–18 months to mature) with an enormous crop water requirement of 1,500 to 2,500 mm per season, relying on constant flood irrigation. Pearl millet (bajra) and Red gram (arhar) are dryland, drought-resilient legumes/millets that thrive on minimal rain, while sunflower has a modest water requirement.

Tethered to: REALM 48: Sugarcane Geography of India

Question 58

Ocean-Atmosphere Dynamics

Consider the following statements:

In the tropical zone, the western sections of the oceans are warmer than the eastern sections owing to the influence of trade winds.
In the temperate zone, westerlies make the eastern sections of oceans warmer than the western sections.

Which of the statements given above is/are correct?

Official Verdict: (c) Both 1 and 2

The Core Concept: Both statements illustrate the direct wind-driven circulation of ocean surface waters. In the tropics, Trade Winds blow consistently from East to West, pushing solar-heated warm surface water toward the western side of ocean basins (e.g., the Western Pacific Warm Pool), while upwelling cold water chills the eastern coasts (1 is true). In temperate latitudes, the prevailing Westerlies blow from West to East, steering warm equatorial current extensions (like the Gulf Stream / North Atlantic Drift) toward the eastern sections of ocean basins, creating mild oceanic climates in western Europe (2 is true).

Tethered to: REALM 94: Ocean Currents & Climate

Question 59

Climate Adaptation Alliances

In the context of India's preparation for Climate-Smart Agriculture, consider the following statements:

The 'Climate-Smart Village' approach in India is a part of a project led by the Climate Change, Agriculture and Food Security (CCAFS), an international research programme.
The project of CCAFS is carried out under Consultative Group on International Agricultural Research (CGIAR) headquartered in France.
The International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) in India is one of the CGIAR's research centres.

Which of the statements given above are correct?

Official Verdict: (d) 1, 2 and 3

The Core Concept: All three institutional statements are correct. The Climate-Smart Village (CSV) project across Haryana, Bihar, and Punjab was piloted by the CCAFS research programme to validate resilient farming techniques (1 is true). CCAFS is coordinated under the global CGIAR consortium, whose headquarters sits in Montpellier, France (2 is true). ICRISAT (headquartered in Patancheru, Telangana) is one of CGIAR's premier global agricultural research centres focusing on dryland grain legumes and cereals (3 is true).

Tethered to: REALM 320: Climate-Smart Agriculture

Question 60

Terrestrial Biome Profiles

"Leaf litter decomposes faster than in any other biome and as a result the soil surface is often almost bare. Apart from trees, the vegetation is largely composed of plant forms that reach up into the canopy vicariously, by climbing the trees or growing as epiphytes, rooted on the upper branches of trees." This is the most likely description of

(a) coniferous forest
(b) dry deciduous forest
(c) mangrove forest
(d) tropical rain forest

Official Verdict: (d) tropical rain forest

The Core Concept: This quote is the quintessential textbook profile of the Tropical Rain Forest. Constant warmth and near-saturation humidity fuel explosive bacterial and fungal decomposer communities, turning leaf litter into soluble nutrients within weeks and leaving forest ground surfaces barren of deep humus. Sunlight cannot penetrate the thick emergent canopy, forcing climbing lianas and woody vines to ascend tree trunks vicariously and orchids/ferns to survive perched as epiphytes in the upper tree crown.

Tethered to: REALM 37: Tropical Rainforest Ecosystems