Our Environment Part 1: MCQs (Q1–Q25)
🌍 Our Environment – MCQs (Class 10 Science, NCERT)
🔹 Part 1: Questions 1–25
Q1. Which of the following is a non-biodegradable substance?
A) Paper
B) Cotton cloth
C) Plastic
D) Cow dung
Correct Answer: C) Plastic
Explanation:
- A) Paper → Biodegradable.
- B) Cotton cloth → Biodegradable.
- ✅ C) Plastic → Non-biodegradable, persists for long.
- D) Cow dung → Biodegradable.
Q2. Which of the following is biodegradable?
A) Polythene bag
B) Vegetable peel
C) Aluminium foil
D) Iron nails
Correct Answer: B) Vegetable peel
Explanation:
- ✅ B) Vegetable peels decompose by microbes.
- A, C, D → Do not easily decompose.
Q3. The ozone layer is found in which part of the atmosphere?
A) Troposphere
B) Mesosphere
C) Stratosphere
D) Exosphere
Correct Answer: C) Stratosphere
Explanation:
- ✅ C) Ozone layer lies in stratosphere, absorbs UV rays.
Q4. Which gas is mainly responsible for depletion of ozone layer?
A) CO₂
B) SO₂
C) CFCs
D) NO₂
Correct Answer: C) CFCs
Explanation:
- ✅ C) Chlorofluorocarbons release chlorine atoms that destroy ozone.
Q5. Which of the following is NOT an abiotic component of the ecosystem?
A) Air
B) Water
C) Soil
D) Producer
Correct Answer: D) Producer
Explanation:
- ✅ D) Producers are living (biotic). Abiotic = air, water, soil.
Q6. Which of the following is a producer in an ecosystem?
A) Cow
B) Tiger
C) Grass
D) Human
Correct Answer: C) Grass
Explanation:
- ✅ C) Grass produces food by photosynthesis.
- A, B, D → Consumers.
Q7. The primary consumers in a food chain are:
A) Plants
B) Herbivores
C) Carnivores
D) Decomposers
Correct Answer: B) Herbivores
Explanation:
- ✅ B) Herbivores directly consume plants.
Q8. Which of the following organisms is a decomposer?
A) Cow
B) Fungi
C) Lion
D) Grass
Correct Answer: B) Fungi
Explanation:
- ✅ B) Fungi break down dead matter into nutrients.
Q9. Which of the following represents a correct food chain?
A) Grass → Cow → Human → Tiger
B) Grass → Goat → Human
C) Grass → Deer → Lion
D) All of these
Correct Answer: D) All of these
Explanation:
- ✅ D) All are valid food chains.
Q10. In an ecosystem, the flow of energy is:
A) Cyclic
B) Linear, unidirectional
C) Reversible
D) Random
Correct Answer: B) Linear, unidirectional
Explanation:
- ✅ B) Energy flows in one direction (Sun → producers → consumers → decomposers).
Q11. Which trophic level has the maximum energy in an ecosystem?
A) Producers
B) Primary consumers
C) Secondary consumers
D) Tertiary consumers
Correct Answer: A) Producers
Explanation:
- ✅ A) Plants capture solar energy → basis of food chain.
Q12. The 10% law of energy transfer in a food chain was given by:
A) Mendel
B) Lindeman
C) Darwin
D) Watson
Correct Answer: B) Lindeman
Explanation:
- ✅ B) Only 10% energy transfers from one trophic level to next.
Q13. The energy available for carnivores in a food chain comes from:
A) Producers directly
B) Herbivores
C) Sun
D) Decomposers
Correct Answer: B) Herbivores
Explanation:
- ✅ B) Carnivores eat herbivores, thus get energy indirectly from producers.
Q14. In the following, which is a secondary consumer?
Grass → Goat → Human
A) Grass
B) Goat
C) Human
D) Sun
Correct Answer: C) Human
Explanation:
- ✅ C) Human eats herbivore (goat), acts as secondary consumer.
Q15. Which group of organisms forms the first trophic level in a food chain?
A) Carnivores
B) Herbivores
C) Producers
D) Decomposers
Correct Answer: C) Producers
Explanation:
- ✅ C) Plants/producers form base of food chain.
Q16. Which of the following is an artificial ecosystem?
A) Forest
B) Pond
C) Aquarium
D) Desert
Correct Answer: C) Aquarium
Explanation:
- ✅ C) Aquarium is man-made ecosystem.
Q17. Which pollutant causes thinning of ozone layer?
A) CO₂
B) CFCs
C) SO₂
D) CH₄
Correct Answer: B) CFCs
Explanation:
- ✅ B) CFCs (refrigerants, aerosols) release chlorine that destroys ozone.
Q18. Which is an example of a natural ecosystem?
A) Garden
B) Aquarium
C) Crop field
D) Pond
Correct Answer: D) Pond
Explanation:
- ✅ D) Pond develops naturally with producers, consumers, decomposers.
Q19. Which type of waste is generated in hospitals?
A) Biodegradable only
B) Non-biodegradable only
C) Both biodegradable and non-biodegradable
D) None
Correct Answer: C) Both biodegradable and non-biodegradable
Explanation:
- ✅ C) Hospital waste includes syringes (non-bio) & bandages (bio).
Q20. Which is NOT an effect of ozone depletion?
A) Skin cancer
B) Eye cataract
C) Immune system damage
D) Increase in oxygen level
Correct Answer: D) Increase in oxygen level
Explanation:
- ✅ D) Ozone depletion doesn’t affect O₂ concentration.
Q21. The organisms which feed on both plants and animals are called:
A) Carnivores
B) Herbivores
C) Omnivores
D) Producers
Correct Answer: C) Omnivores
Explanation:
- ✅ C) Humans, bears are omnivores.
Q22. Which one of the following is NOT an ecosystem service?
A) Pollination
B) Climate regulation
C) Plastic recycling
D) Soil fertility
Correct Answer: C) Plastic recycling
Explanation:
- ✅ C) Ecosystems cannot recycle plastic naturally.
Q23. Which of the following is the top consumer in a forest food chain?
A) Deer
B) Lion
C) Tiger
D) Both B and C
Correct Answer: D) Both B and C
Explanation:
- ✅ D) Lion & tiger are apex predators in forest food chains.
Q24. The main cause of environmental pollution is:
A) Solar energy
B) Human activities
C) Plants
D) Decomposers
Correct Answer: B) Human activities
Explanation:
- ✅ B) Industrialisation, deforestation, waste → pollution.
Q25. Which of the following is a greenhouse gas?
A) CO₂
B) O₂
C) N₂
D) H₂
Correct Answer: A) CO₂
Explanation:
- ✅ A) Carbon dioxide traps heat, causes greenhouse effect.
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