UPSC 2022: Nexus 21—30

Agricultural Ecology, Global Geomorphology, Solstices & Rare Earths. [Set A]

Question 21

Agri-Emissions

Among the following crops, which one is the most important anthropogenic source of both methane and nitrous oxide?

(a) Cotton
(b) Rice
(c) Sugarcane
(d) Wheat

Official Verdict: (b) Rice

The Core Concept: Traditional wetland rice cultivation is a massive driver of climate change. The prolonged flooding of rice paddies cuts off oxygen to the soil, creating an anaerobic environment where methanogenic bacteria thrive, releasing huge volumes of Methane ($CH_4$). Simultaneously, the heavy application of synthetic nitrogen fertilizers in these waterlogged soils leads to denitrification, releasing Nitrous Oxide ($N_2O$)—a greenhouse gas nearly 300 times more potent than carbon dioxide.

Tethered to: REALM 213: Agriculture & Climate Change

Question 22

Sustainable Agriculture

"System of Rice Intensification" of cultivation, in which alternate wetting and drying of rice fields is practised, results in:

Reduced seed requirement
Reduced methane production
Reduced electricity consumption

Select the correct answer using the code given below.

Official Verdict: (d) 1, 2 and 3

The Core Concept: The System of Rice Intensification (SRI) is an agro-ecological methodology. Instead of planting clumps of mature seedlings in flooded paddies, SRI uses very young, single seedlings spaced widely apart (drastically reducing seed requirement). Crucially, it employs "alternate wetting and drying" rather than continuous flooding. By keeping the soil moist but aerated, anaerobic methanogens cannot thrive (drastically reducing methane production). Since fields aren't continuously flooded, groundwater pumping drops significantly (reducing electricity consumption).

Tethered to: REALM 319: Sustainable Agriculture

Question 23

Global Landforms & Climate

Which one of the following lakes of West Africa has become dry and turned into a desert?

(a) Lake Victoria
(b) Lake Faguibine
(c) Lake Oguta
(d) Lake Volta

Official Verdict: (b) Lake Faguibine

The Core Concept: Located in Mali at the edge of the Sahara Desert, Lake Faguibine was once a massive, thriving ecosystem fed by annual floods of the Niger River. Due to severe, prolonged droughts starting in the 1970s and changing climate patterns, the lake completely dried up, replacing a vibrant fishery and agricultural hub with barren, encroaching desert sands. (Lake Victoria and Lake Volta remain massive extant water bodies, and Lake Oguta is in Nigeria).

Tethered to: REALM 61: Global Landform Atlas

Question 24

Fluvial Landforms

Gandikota canyon of South India was created by which one of the following rivers?

(a) Cauvery
(b) Manjira
(c) Pennar
(d) Tungabhadra

Official Verdict: (c) Pennar

The Core Concept: Dubbed the "Grand Canyon of India," the breathtaking Gandikota gorge in Andhra Pradesh was carved relentlessly over millennia by the flow of the Pennar River slicing through the rugged, layered red granite and quartzite of the Erramala hills.

Tethered to: REALM 45: Fluvial Erosional Landforms

Question 25

Himalayan Topography

Consider the following pairs:

1. Namcha Barwa: Garhwal Himalaya
2. Nanda Devi: Kumaon Himalaya
3. Nokrek: Sikkim Himalaya

Which of the pairs given above is/are correctly matched?

Official Verdict: (b) 2 only

The Core Concept: Namcha Barwa is the far-eastern anchor of the Himalayas, located in Tibet/Arunachal Pradesh, far away from the Garhwal (Uttarakhand) region (1 is false). Nanda Devi, India's second-highest peak, sits majestically in the Kumaon Himalayas of Uttarakhand (2 is true). Nokrek is the highest peak of the Garo Hills in Meghalaya, completely disconnected from the Sikkim Himalayas (3 is false).

Tethered to: REALM 08: Himalayan Regional Divisions

Question 26

Geopolitical Nomenclature

The term "Levant" often heard in the news roughly corresponds to which of the following regions?

(a) Region along the eastern Mediterranean shores
(b) Region along North African shores stretching from Egypt to Morocco
(c) Region along Persian Gulf and Horn of Africa
(d) The entire coastal areas of Mediterranean Sea

Official Verdict: (a) Region along the eastern Mediterranean shores

The Core Concept: Historically deriving from the French word meaning "to rise" (where the sun rises in the East), the Levant refers strictly to the eastern seaboard of the Mediterranean Sea. Today, this geopolitical term encompasses modern-day Syria, Lebanon, Israel, Palestine, Jordan, and Cyprus.

Tethered to: REALM 114: West Asia → Energy → Chabahar → Red Sea

Question 27

Geopolitical Map

Consider the following countries:

Azerbaijan
Kyrgyzstan
Tajikistan
Turkmenistan
Uzbekistan

Which of the above have borders with Afghanistan?

Official Verdict: (c) 3, 4 and 5 only

The Core Concept: Afghanistan is a landlocked pivot state. To its north, it shares direct borders with three Central Asian republics: Turkmenistan, Uzbekistan, and Tajikistan (3, 4, 5). Kyrgyzstan sits further northeast, blocked by Tajikistan. Azerbaijan is located entirely across the Caspian Sea in the Caucasus, sharing no border with Afghanistan.

Tethered to: REALM 122 TO 140: Contemporary IR World Map

Question 28

Strategic Minerals

With reference to India, consider the following statements:

Monazite is a source of rare earths.
Monazite contains thorium.
Monazite occurs naturally in the entire Indian coastal sands in India.
In India, Government bodies only can process or export monazite.

Which of the statements given above are correct?

Official Verdict: (b) 1, 2 and 4 only

The Core Concept: Monazite is a radioactive reddish-brown phosphate mineral that is a critical ore for Rare Earth Elements (REEs) and Thorium (essential for India's 3-stage nuclear program) (1 and 2 are true). Because of its radioactivity and strategic nuclear value, the Atomic Energy (Working of the Mines, Minerals and Handling of Prescribed Substances) Rules strictly dictate that only government bodies (like IREL) can mine, process, or export it (4 is true). However, it does not occur across the "entire" Indian coast; it is heavily concentrated in specific placer deposits in Kerala (Chavara), Tamil Nadu, and Odisha (3 is false).

Tethered to: REALM 457: Nuclear Fuels (Uranium/Thorium)

Question 29

Orbital Mechanics

In the northern hemisphere, the longest day of the year normally occurs in the:

(a) First half of the month of June
(b) Second half of the month of June
(c) First half of the month of July
(d) Second half of the month of July

Official Verdict: (b) Second half of the month of June

The Core Concept: The longest day of the year in the Northern Hemisphere occurs on the Summer Solstice, when the North Pole achieves its maximum axial tilt (23.5 degrees) directly toward the Sun, and the Sun's rays fall perfectly vertical on the Tropic of Cancer. This astronomical event reliably occurs on or around June 21st, squarely placing it in the second half of the month of June.

Tethered to: REALM 07: Motions of Earth & Effects

Question 30

Ramsar Geography

Consider the following pairs:

1. Hokera Wetland: Punjab
2. Renuka Wetland: Himachal Pradesh
3. Rudrasagar Lake: Tripura
4. Sasthamkotta Lake: Tamil Nadu

How many pairs given above are correctly matched?

Official Verdict: (b) Only two pairs

The Core Concept: Hokera (Hokersar) is a vital avian wintering staging ground located in Jammu and Kashmir, not Punjab (1 is false). Renuka Lake is situated in the Sirmaur district of Himachal Pradesh (2 is true). Rudrasagar Lake (Twijilikma) is a lowland sedimentation reservoir in Tripura featuring the famous Neermahal water palace (3 is true). Sasthamkotta Lake is the largest freshwater lake in Kerala, named after the ancient Sastha temple on its bank, not Tamil Nadu (4 is false).

Tethered to: REALM 57: Ramsar Sites of India