CTET EVS Most Important MCQ’s Answer With Explanation

Environmental Science (EVS) for CTET, along with answers and explanations:

1. Question: What is the primary source of energy for all living organisms?
   • A. Water
   • B. Sunlight
   • C. Wind
   • D. Fossil fuels
   Answer: B. SunlightExplanation: Sunlight is the primary source of energy for photosynthesis, the process by which green plants produce food.
2. Question: Which gas is most abundant in the Earth’s atmosphere?
   • A. Oxygen
   • B. Nitrogen
   • C. Carbon dioxide
   • D. Hydrogen
   Answer: B. NitrogenExplanation: Nitrogen constitutes about 78% of Earth’s atmosphere.
3. Question: What is the main cause of ozone layer depletion?
   • A. Carbon dioxide emissions
   • B. Methane emissions
   • C. Chlorofluorocarbons (CFCs)
   • D. Sulfur dioxide emissions
   Answer: C. Chlorofluorocarbons (CFCs)Explanation: CFCs released into the atmosphere break down ozone molecules in the stratosphere.
4. Question: Which of the following is a non-renewable resource?
   • A. Solar energy
   • B. Wind energy
   • C. Coal
   • D. Biomass
   Answer: C. CoalExplanation: Coal is a non-renewable fossil fuel formed from the remains of plants that lived and died millions of years ago.
5. Question: What is the main purpose of a wetland?
   • A. Agriculture
   • B. Recreation
   • C. Biodiversity conservation
   • D. Urban development
   Answer: C. Biodiversity conservationExplanation: Wetlands provide habitat for diverse plant and animal species and contribute to biodiversity conservation.
6. Question: Which of the following is a greenhouse gas?
   • A. Oxygen
   • B. Nitrous oxide
   • C. Nitrogen
   • D. Argon
   Answer: B. Nitrous oxideExplanation: Nitrous oxide is a potent greenhouse gas that contributes to global warming.
7. Question: What is the purpose of the 3 R’s in environmental conservation?
   • A. Recreation, Reuse, Recycle
   • B. Reduce, Reuse, Recycle
   • C. Refuse, Repair, Recycle
   • D. Recycle, Replenish, Restore
   Answer: B. Reduce, Reuse, RecycleExplanation: The 3 R’s aim to minimize waste and promote sustainable consumption patterns.
8. Question: Which of the following is a renewable source of energy?
   • A. Natural gas
   • B. Nuclear power
   • C. Geothermal energy
   • D. Coal
   Answer: C. Geothermal energyExplanation: Geothermal energy is generated from the heat of the Earth’s interior and is considered a renewable resource.
9. Question: What is the role of decomposers in an ecosystem?
   • A. Produce oxygen
   • B. Break down dead organic matter
   • C. Capture sunlight for energy
   • D. Pollinate flowers
   Answer: B. Break down dead organic matterExplanation: Decomposers, like bacteria and fungi, break down dead organic material into simpler substances, returning nutrients to the soil.
10. Question: Which of the following is a waterborne disease?
    • A. Influenza
    • B. Malaria
    • C. Cholera
    • D. Tuberculosis
    Answer: C. CholeraExplanation: Cholera is a waterborne disease caused by the Vibrio cholerae bacterium.
11. Question: What is the main component of the Earth’s core?
    • A. Iron
    • B. Nickel
    • C. Silicon
    • D. Aluminum
    Answer: A. IronExplanation: The Earth’s core is primarily composed of iron and nickel.
12. Question: Which layer of the Earth’s atmosphere is closest to the surface?
    • A. Stratosphere
    • B. Troposphere
    • C. Mesosphere
    • D. Exosphere
    Answer: B. TroposphereExplanation: The troposphere is the lowest layer of the Earth’s atmosphere where weather events occur.
13. Question: What is the primary function of the ozone layer in the stratosphere?
    • A. Reflect sunlight
    • B. Absorb ultraviolet (UV) radiation
    • C. Generate heat
    • D. Facilitate photosynthesis
    Answer: B. Absorb ultraviolet (UV) radiationExplanation: The ozone layer absorbs the majority of the sun’s harmful ultraviolet radiation.
14. Question: Which of the following is a renewable resource derived from plants?
    • A. Natural gas
    • B. Petroleum
    • C. Biomass
    • D. Uranium
    Answer: C. BiomassExplanation: Biomass refers to organic materials, such as plants and crop residues, used as a source of energy.
15. Question: What is the primary cause of soil erosion?
    • A. Deforestation
    • B. Urbanization
    • C. Agriculture
    • D. Mining
    Answer: A. DeforestationExplanation: Deforestation removes protective vegetation, leading to soil erosion by wind and water.
16. Question: Which of the following is a renewable energy source that harnesses the Earth’s natural heat?
    • A. Solar power
    • B. Wind energy
    • C. Hydroelectric power
    • D. Geothermal energy
    Answer: D. Geothermal energyExplanation: Geothermal energy uses heat from the Earth’s interior to generate power.
17. Question: What is the main cause of acid rain?
    • A. Carbon monoxide emissions
    • B. Nitrogen oxide emissions
    • C. Sulfur dioxide emissions
    • D. Methane emissions
    Answer: C. Sulfur dioxide emissionsExplanation: Sulfur dioxide released into the atmosphere reacts with water vapor to form acid rain.
18. Question: Which of the following is an example of a non-biodegradable waste?
    • A. Food scraps
    • B. Paper
    • C. Plastic
    • D. Leaves
    Answer: C. PlasticExplanation: Plastics are synthetic materials that do not easily break down in the environment.
19. Question: What is the main purpose of the ozone layer in the stratosphere?
    • A. Reflect sunlight
    • B. Absorb ultraviolet (UV) radiation
    • C. Generate heat
    • D. Facilitate photosynthesis
    Answer: B. Absorb ultraviolet (UV) radiationExplanation: The ozone layer absorbs the majority of the sun’s harmful ultraviolet radiation.
20. Question: Which gas is responsible for the greenhouse effect on Earth?
    • A. Oxygen
    • B. Carbon monoxide
    • C. Methane
    • D. Carbon dioxide
    Answer: D. Carbon dioxideExplanation: Carbon dioxide is a major greenhouse gas that contributes to the trapping of heat in the Earth’s atmosphere.
21. Question: What is the primary function of wetlands in an ecosystem?
    • A. Control floods
    • B. Provide habitat for aquatic species
    • C. Support agriculture
    • D. Generate electricity
    Answer: B. Provide habitat for aquatic speciesExplanation: Wetlands serve as important habitats for various aquatic plants and animals.
22. Question: Which of the following is a renewable resource obtained from the sun’s rays?
    • A. Biomass
    • B. Geothermal energy
    • C. Solar power
    • D. Natural gas
    Answer: C. Solar powerExplanation: Solar power harnesses energy from the sun through the use of solar panels.
23. Question: What is the primary role of the World Wildlife Fund (WWF)?
    • A. Humanitarian aid
    • B. Wildlife conservation
    • C. Environmental education
    • D. Space exploration
    Answer: B. Wildlife conservationExplanation: The World Wildlife Fund focuses on the conservation of endangered species and their habitats.
24. Question: Which of the following is a method to reduce air pollution?
    • A. Deforestation
    • B. Use of electric vehicles
    • C. Open burning of waste
    • D. Increased industrial emissions
    Answer: B. Use of electric vehiclesExplanation: Electric vehicles produce fewer emissions compared to traditional gasoline-powered vehicles, reducing air pollution.
25. Question: What is the main cause of the greenhouse effect?
    • A. Human activities
    • B. Natural disasters
    • C. Volcanic eruptions
    • D. Meteorite impacts
    Answer: A. Human activitiesExplanation: Human activities, such as burning fossil fuels, contribute to the increase in greenhouse gases, leading to the greenhouse effect.
26. Question: Which of the following is a renewable source of energy that depends on the Earth’s gravitational force?
    • A. Wind energy
    • B. Solar power
    • C. Hydroelectric power
    • D. Geothermal energy
    Answer: C. Hydroelectric powerExplanation: Hydroelectric power harnesses the energy of flowing water to generate electricity.
27. Question: What is the primary function of the United Nations Environment Programme (UNEP)?
    • A. Promote world peace
    • B. Provide humanitarian aid
    • C. Coordinate global environmental initiatives
    • D. Space exploration
    Answer: C. Coordinate global environmental initiativesExplanation: UNEP works to address global environmental challenges and promote sustainable development.
28. Question: Which of the following is a renewable resource derived from the movement of air?
    • A. Solar power
    • B. Biomass
    • C. Wind energy
    • D. Natural gas
    Answer: C. Wind energyExplanation: Wind energy harnesses the kinetic energy of moving air to generate electricity.
29. Question: What is the main purpose of the Red List published by the International Union for Conservation of Nature (IUCN)?
    • A. Weather forecasting
    • B. Wildlife conservation
    • C. Global trade regulation
    • D. Human health monitoring
    Answer: B. Wildlife conservationExplanation: The Red List assesses the conservation status of various species, helping prioritize conservation efforts.
30. Question: Which of the following is a renewable resource obtained from the Earth’s heat?
    • A. Biomass
    • B. Solar power
    • C. Wind energy
    • D. Geothermal energy
    Answer: D. Geothermal energyExplanation: Geothermal energy harnesses the heat from the Earth’s interior to produce electricity.
31. Question: What is the main cause of deforestation?
    • A. Urbanization
    • B. Agricultural expansion
    • C. Recycling initiatives
    • D. Marine pollution
    Answer: B. Agricultural expansionExplanation: Clearing land for agriculture is a major driver of deforestation.
32. Question: Which of the following is an example of a renewable resource obtained from flowing water?
    • A. Biomass
    • B. Hydroelectric power
    • C. Wind energy
    • D. Natural gas
    Answer: B. Hydroelectric powerExplanation: Hydroelectric power harnesses the energy of flowing water to generate electricity.
33. Question: What is the primary function of the Environmental Protection Agency (EPA)?
    • A. Promote space exploration
    • B. Enforce environmental regulations
    • C. Provide humanitarian aid
    • D. Regulate international trade
    Answer: B. Enforce environmental regulationsExplanation: The EPA is responsible for enforcing environmental laws and regulations in the United States.
34. Question: Which of the following is a renewable resource obtained from organic waste?
    • A. Biomass
    • B. Solar power
    • C. Wind energy
    • D. Geothermal energy
    Answer: A. BiomassExplanation: Biomass refers to organic materials, including plant and animal waste, used as a source of energy.
35. Question: What is the main cause of water pollution from industrial sources?
    • A. Deforestation
    • B. Agricultural runoff
    • C. Disposal of hazardous waste
    • D. Oil spills
    Answer: C. Disposal of hazardous wasteExplanation: Improper disposal of hazardous waste from industries contributes to water pollution.
36. Question: Which of the following is a method to reduce soil erosion?
    • A. Urbanization
    • B. Planting cover crops
    • C. Deforestation
    • D. Overgrazing
    Answer: B. Planting cover cropsExplanation: Cover crops help prevent soil erosion by protecting the soil surface.
37. Question: What is the primary cause of coral reef degradation?
    • A. Ocean currents
    • B. Climate change
    • C. Oil exploration
    • D. Soil erosion
    Answer: B. Climate changeExplanation: Climate change, including rising sea temperatures, poses a significant threat to coral reefs.
38. Question: Which of the following is a renewable resource obtained from the sun’s heat?
    • A. Solar power
    • B. Biomass
    • C. Wind energy
    • D. Geothermal energy
    Answer: A. Solar powerExplanation: Solar power harnesses the energy from the sun’s heat using solar panels.