General Science PYQ – Environment and Ecology – Part 1 (Q 1–34)
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General Science PYQ – Environment and Ecology – Part 1 (Q 1–34) – 32 questions, subject: Science. Every question has the correct answer with a one-line explanation; tap "Show Answer". Free practice for TNPSC, UPSC, SSC, Bank and RRB exams – Shanmugam IAS Academy, Coimbatore.
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1.
Junior Rehabilitation Officer 2023
The two major components of an Ecosystem areCorrect Answer: C [Abiotic and Biotic]
Explanation:
The two major components of an ecosystem are the abiotic (non-living) and biotic (living) components.
2.
1. Mineral components like Ca, Mg, P, N, S
2. Climatic factors like light, temperature, water, pH, turbidity etc
3. Producers and Consumers
4. Decomposers/Saprotrophs
Group 1B/1C 2024
The important abiotic components of a fresh water ecosystem are:1. Mineral components like Ca, Mg, P, N, S
2. Climatic factors like light, temperature, water, pH, turbidity etc
3. Producers and Consumers
4. Decomposers/Saprotrophs
Correct Answer: A [1 and 2]
Explanation:
Mineral components such as Ca, Mg, P, N, S and climatic factors like light and temperature are abiotic components of a freshwater ecosystem, whereas producers and consumers are biotic.
3.
(a) Abiotic component – 1. The crushed cane after extraction of juice
(b) Bagasse – 2. Animals that feed on other animals
(c) Carcinogen – 3. Non-living component in an eco system
(d) Carnivorous – 4. Toxic organic compound causing cancer
Group 1/1A 2025
Match the following and find out the correct sequence.(a) Abiotic component – 1. The crushed cane after extraction of juice
(b) Bagasse – 2. Animals that feed on other animals
(c) Carcinogen – 3. Non-living component in an eco system
(d) Carnivorous – 4. Toxic organic compound causing cancer
Correct Answer: C [3 1 4 2]
Explanation:
Abiotic component is the non-living part of an ecosystem, bagasse is crushed cane after juice extraction, and the other terms match as per the keyed sequence 3 1 4 2.
4.
EO Group VII (HR&CE) 2022
"Life on earth is solar powered". This statement is true becauseCorrect Answer: C [Plants produce energy by photosynthesis using solar lights]
Explanation:
Life is solar powered because green plants capture sunlight in photosynthesis and this food energy passes to all organisms through food chains.
5.
(i) Energy flow is the key function
(ii) The flow of energy in the ecosystem is through food chain and food web
(iii) Transfer of energy not follows thermodynamic laws
CTS (Interview Posts) 2026
Which of the following statements are true about the functions of ecosystem?(i) Energy flow is the key function
(ii) The flow of energy in the ecosystem is through food chain and food web
(iii) Transfer of energy not follows thermodynamic laws
Correct Answer: C [(i) and (ii) only]
Explanation:
Energy flow is the key function of an ecosystem and it obeys the laws of thermodynamics, with energy lost as heat at each step, so (i) and (ii) are true.
6.
GSASO 2020
Sequence of organism through which passing of the organic molecules in a community is calledCorrect Answer: B [Food chain]
Explanation:
The sequence of organisms through which food energy passes in a community is a food chain, e.g. grass, grasshopper, frog, snake, eagle.
7.
Jailor 2023
A food web consists ofCorrect Answer: C [interlocking food chains]
Explanation:
A food web is a network of interlocking food chains that gives stability to the ecosystem.
8.
Asst. Public Prosecutor Gr. II 2025
In an ecosystem, consumers that feed at all levels areCorrect Answer: D [Parasites, Scavengers and Decomposers]
Explanation:
Parasites, scavengers and decomposers obtain food from organisms at all trophic levels.
9.
Group 2 2022
The interaction of biotic potential with environmental resources, as seen in populations showing the S-shaped growth curve, is given as dN/dt = rN(K – N)/K, where N is the number of individuals in the population, t is the time, r is the biotic potential of the organism concerned, and K stands forCorrect Answer: A [Carrying capacity]
Explanation:
In the S-shaped growth equation dN/dt = rN(K - N)/K, K is the carrying capacity, the maximum population a habitat can support.
10.
Group 1 2022
The process of establishment of an organism in a new habitat is known asCorrect Answer: A [Ecesis]
Explanation:
Ecesis is the successful establishment, growth and reproduction of an organism that has arrived in a new habitat.
11.
CTS (Interview Posts) 2024
Choose the correct order for different phases of biotic successionCorrect Answer: B [Nudation - Migration - Ecesis - Reaction - Stabilization]
Explanation:
Biotic succession proceeds as nudation, migration, ecesis, reaction and stabilization.
12.
District Educational Officer 2023
Enclosed and essentially self sufficient (but not necessarily isolated) experimental environment or ecosystem that is on a larger scale is known asCorrect Answer: A [Mesocosm]
Explanation:
A mesocosm is an enclosed, largely self-sufficient experimental ecosystem larger than a microcosm that models part of the natural environment.
13.
District Educational Officer 2023
The largest ecosystem in the world isCorrect Answer: B [Ocean ecosystem]
Explanation:
The ocean ecosystem covers about 71 per cent of Earth's surface and is the largest ecosystem.
14.
Veterinary Assistant 2023
Which one of the following is not marine ecosystem?Correct Answer: D [Lake]
Explanation:
A lake is a freshwater ecosystem, whereas estuaries, coral reefs and the sea are marine ecosystems.
15.
Group 1 2021
Which of the following organisms is the producer of the ocean?Correct Answer: C [Phytoplankton]
Explanation:
Phytoplankton such as diatoms and algae are the primary producers of the ocean, forming the base of the marine food chain.
16.
Executive Officer Gr. III (HR&CE) 2022
How do you call the organisms inhabit the bottom of the aquatic bodies?Correct Answer: C [Benthic]
Explanation:
Organisms living at the bottom of water bodies are called benthic organisms or benthos.
17.
(a) Hydrosphere – 1. Lies above 50 km which coincides with the thermosphere
(b) Lithosphere – 2. Earth's crust and a lower portion of the mantle
(c) Biosphere – 3. Earth's water which exists in both fresh and saline form
(d) Ionosphere – 4. Lithosphere, hydrosphere and atmosphere in which living organisms live
Agricultural Officer 2023
Match the following:(a) Hydrosphere – 1. Lies above 50 km which coincides with the thermosphere
(b) Lithosphere – 2. Earth's crust and a lower portion of the mantle
(c) Biosphere – 3. Earth's water which exists in both fresh and saline form
(d) Ionosphere – 4. Lithosphere, hydrosphere and atmosphere in which living organisms live
Correct Answer: A [3 2 4 1]
Explanation:
Hydrosphere is Earth's water, lithosphere the crust and upper mantle, biosphere the zone of life and atmosphere the gaseous layer, giving the keyed matching 3 2 4 1.
18.
Combined Research Assistant 2023
The largest division of geological time isCorrect Answer: A [Eon]
Explanation:
The eon is the largest division of geological time, divided into eras, periods and epochs.
19.
Group 1 2024
The portion of the solar radiation that the Earth's surface reflects back isCorrect Answer: A [Albedo]
Explanation:
The fraction of solar radiation reflected back by Earth's surface is called albedo.
20.
CTS (Interview Posts-II) 2024
The atmosphere consists of a mixture of gases having a relatively uniform composition in the lower layers close to the earth. Pure dry air on an average constitutes mainly nitrogen, oxygen and other gases (argon, CO₂, H₂, He and O₃). The composition can be represented asCorrect Answer: B [78%, 21% and 1%]
Explanation:
Dry air has roughly 78 per cent nitrogen, 21 per cent oxygen and 1 per cent argon and other gases by volume.
21.
Group 1 2022 · Junior Rehabilitation Officer 2023
Which gas in the atmosphere saves us from the ultraviolet rays of the sun?Correct Answer: B [Ozone]
Explanation:
The ozone layer in the stratosphere absorbs harmful ultraviolet rays of the Sun and protects life on Earth.
22.
Group 1 2022
The instrument used to measure the atmospheric ozone concentration isCorrect Answer: A [Dobsonmeter]
Explanation:
Atmospheric ozone is measured with the Dobson spectrophotometer (Dobson meter) in Dobson units.
23.
CTS (Interview Posts) 2026
On the ozone layer, the chlorofluoro hydro carbon has continuing their effect asCorrect Answer: C [In reactions, the chlorine atoms formed by them serves as catalysts leading to the degradation of ozone.]
Explanation:
UV light splits CFCs releasing chlorine atoms that act as catalysts and are regenerated, so each destroys thousands of ozone molecules.
24.
Health Officer 2023
Which halocarbon has a long atmospheric lifetime?Correct Answer: A [Chlorofluorocarbons]
Explanation:
Chlorofluorocarbons are very stable and persist in the atmosphere for decades to a century, longer than the other halocarbons listed.
25.
Group 1 2021
The pollutant which cause impairment in plant metabolism isCorrect Answer: C [Sulphur di oxide]
Explanation:
Sulphur dioxide enters leaf pores and destroys chlorophyll causing chlorosis, thereby impairing plant metabolism.
26.
AD Town & Country Planning 2022
The main constituents of photochemical smog areCorrect Answer: C [Oxides of nitrogen, ozone and hydrocarbons]
Explanation:
Photochemical smog forms in sunlight from oxides of nitrogen and hydrocarbons and contains ozone and PAN.
27.
(a) CO₂ – 1. Ground water pollution and particulate in air
(b) NOₓ – 2. Global warming
(c) Lead (Pb) – 3. Acid rain
(d) Hydrocarbons (HC) – 4. An ingredient for the formation of photochemical smog
Group 2/2A 2024
Match the following:(a) CO₂ – 1. Ground water pollution and particulate in air
(b) NOₓ – 2. Global warming
(c) Lead (Pb) – 3. Acid rain
(d) Hydrocarbons (HC) – 4. An ingredient for the formation of photochemical smog
Correct Answer: A [2 3 1 4]
Explanation:
CO2 causes global warming, NOx acid rain, lead ground water and particulate pollution, and hydrocarbons photochemical smog, giving 2 3 1 4.
28.
Group 1 2022 · CTS (Interview Posts) 2025
Acid rains are produced byCorrect Answer: A [Excess NO₂ and SO₂ from burning fossil fuels]
Explanation:
Acid rain is caused by oxides of nitrogen and sulphur from burning fossil fuels reacting with atmospheric water to form nitric and sulphuric acids.
29.
Reason [R]: Atmosphere contains oxides of nitrogen and sulphur produced by combustion of fuels.
Group 2A Mains 2025
Assertion [A]: Acid rain means the presence of acids in rain water.Reason [R]: Atmosphere contains oxides of nitrogen and sulphur produced by combustion of fuels.
Correct Answer: D [Both [A] and [R] are true and [R] is the correct explanation of [A]]
Explanation:
Acid rain is rain containing acids, and the acids arise from oxides of nitrogen and sulphur in the atmosphere, so the reason correctly explains the assertion.
30.
(1) It is mainly due to incomplete combustion of fuel.
(2) They are more evident in petrol engines.
(3) Long-term exposure can cause nausea.
Group 2/2A 2025
Which of the following statements are correct in the context of carbon monoxide emissions?(1) It is mainly due to incomplete combustion of fuel.
(2) They are more evident in petrol engines.
(3) Long-term exposure can cause nausea.
Correct Answer: C [(1), (2) and (3)]
Explanation:
Carbon monoxide arises from incomplete combustion, is higher in petrol than diesel exhaust and binds haemoglobin, so all three statements are correct.
31.
Asst. Public Prosecutor Gr. II 2026
Gasoline combustion in vehicles produces carbon monoxide, various hydrocarbons, types of organic acids, ammonia, carbon particles and heavy metals like lead. Incomplete burning of fuel produces a hydrocarbon known asCorrect Answer: A [3,4-benzopyrene]
Explanation:
Incomplete combustion of fuel in vehicles forms 3,4-benzopyrene, a carcinogenic polycyclic aromatic hydrocarbon.
32.
Asst. Public Prosecutor Gr. II 2025
A toxic substance produced through burning of plastic isCorrect Answer: A [Dioxins]
Explanation:
Burning plastic, especially PVC, releases highly toxic dioxins and furans.
? Full explanations with tables – General Science PYQ book (₹149): www.shanmugamiasacademy.in/study-materials/tnpsc-general-science-pyq
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