Q80. Which of the listed animals is a fish rather than a bird?
[UPSC CSE Prelims GS Paper I (2022)]
(A) Golden mahseer
(B) Indian nightjar
(C) Spoonbill
(D) White ibis
Answer: (A) Golden mahseer
Explanation: The golden mahseer is a large freshwater cyprinid fish valued in Himalayan river ecosystems. Nightjars, spoonbills and ibises are all bird groups. Common names can be deceptive when species are encountered only in lists.
Q79. In the WHO air-quality context, which statements are correct?
1. PM2.5 guideline: 15 µg/m³ daily and 5 µg/m³ annually.
2. Ozone peaks chiefly in inclement weather.
3. PM10 regularly enters the bloodstream.
4. High ozone worsens asthma.
[UPSC CSE Prelims GS Paper I (2022)]
(A) 1, 3 and 4
(B) 1 and 4 only
(C) 2, 3 and 4
(D) 1 and 2 only
Answer: (B) 1 and 4 only
Explanation: The WHO 2021 guidance specifies stringent PM2.5 concentration limits, and ozone exposure can trigger asthma. Ozone typically forms under sunny photochemical conditions; fine particles such as PM2.5 penetrate farther into lungs than the larger PM10 fraction.
Q78. Which statements on the Himalayan mushroom guchhi are correct?
1. It is a fungus.
2. It occurs naturally in Himalayan forests.
3. It is widely commercially cultivated in north-eastern foothills.
[UPSC CSE Prelims GS Paper I (2022)]
(A) 1 only
(B) 3 only
(C) 1 and 2 only
(D) 2 and 3 only
Answer: (C) 1 and 2 only
Explanation: Guchhi refers to prized morel mushrooms found in parts of the Himalayas. They are fungi collected mainly from wild habitats. The claim of established large-scale commercial cultivation in the stated region is not correct.
Q77. What does the Climate Action Tracker represent?
[UPSC CSE Prelims GS Paper I (2022)]
(A) Independent research consortium assessing national climate pledges
(B) Department within the IPCC
(C) Official UNFCCC committee
(D) UNEP–World Bank regulator
Answer: (A) Independent research consortium assessing national climate pledges
Explanation: Climate Action Tracker evaluates emissions targets and national policies through independent research organisations. Its assessments help compare promises with pathways compatible with temperature goals. It is not an official enforcement office within the United Nations system.
Q76. For rice grown through alternate wetting and drying, what gains may occur?
1. Less seed required.
2. Less methane.
3. Lower irrigation electricity use.
[UPSC CSE Prelims GS Paper I (2022)]
(A) 1 and 2 only
(B) 2 and 3 only
(C) 1 and 3 only
(D) 1, 2 and 3
Answer: (D) 1, 2 and 3
Explanation: System of Rice Intensification methods can require fewer seeds and enable intermittent field drying, reducing methane-producing anaerobic periods. Water savings may lower pumping demand and electricity consumption. Outcomes vary with field management and local conditions.
Q75. The scientific study of relationships between organisms and their surroundings is called:
[WBCS Mains – Environmental Science (2022)]
(A) Ecology
(B) Ecosystem
(C) Phytogeography
(D) Ethology
Answer: (A) Ecology
Explanation: Ecology examines interactions between organisms and environmental factors, including food chains, population dynamics and nutrient cycles. An ecosystem is the functioning unit studied, not the name of the scientific discipline.
Q74. Cultural eutrophication is primarily associated with which type of pollution?
[WBCS Mains – Environmental Science (2022)]
(A) Noise
(B) Thermal
(C) Soil
(D) Water
Answer: (D) Water
Explanation: Human inputs of fertilisers and sewage increase nutrients in lakes and reservoirs. Such enrichment promotes algal growth and can lead to oxygen depletion when organic matter decomposes, creating water-quality problems.
Q73. Which process produces drinking water from saline water?
[WBCS Mains – Environmental Science (2022)]
(A) Desalination
(B) Groundwater mining
(C) Sublimation
(D) Transpiration
Answer: (A) Desalination
Explanation: Desalination removes dissolved salts from seawater or brackish supplies, commonly using reverse osmosis or thermal methods. Groundwater mining merely extracts water and does not necessarily make a saline source drinkable.
Q72. Which process converts nitrate in contaminated water into nitrogen gas?
[WBCS Mains – Environmental Science (2022)]
(A) Nitrification
(B) Nitrogen fixation
(C) Denitrification
(D) Assimilation
Answer: (C) Denitrification
Explanation: Under suitable oxygen-limited conditions, denitrifying bacteria reduce nitrate stepwise to gaseous nitrogen products. It is widely used in wastewater treatment to remove excess nitrogen and prevent downstream eutrophication.
Q71. Why is atmospheric carbon dioxide associated with a warming effect?
[WBCS Mains – Environmental Science (2022)]
(A) It absorbs water vapour and stores its heat
(B) It primarily absorbs solar ultraviolet rays
(C) It traps every wavelength of solar radiation
(D) It absorbs outgoing terrestrial infrared radiation
Answer: (D) It absorbs outgoing terrestrial infrared radiation
Explanation: Greenhouse gases absorb and re-emit part of the long-wave infrared radiation emitted by Earth. This slows heat loss to space, creating the greenhouse effect rather than absorbing all incoming sunlight.
