Class 10 Science (NCERT)

1. Which of the following is a biodegradable substance?

• A. Plastic bottles
• B. Glass pieces
• C. Cotton cloth
• D. DDT

2. Organisms that synthesize their own food using inorganic substances are called:

• A. Herbivores
• B. Autotrophs (Producers)
• C. Decomposers
• D. Carnivores

3. According to Lindeman's 10% law, how much energy is transferred from one trophic level to the next higher level?

• A. 1%
• B. 10%
• C. 50%
• D. 90%

4. Green plants in a terrestrial ecosystem capture about what percentage of the energy of sunlight that falls on their leaves?

• A. 1%
• B. 10%
• C. 25%
• D. 50%

5. Chemical formula of Ozone molecule is:

• A. O
• B. O₂
• C. O₃
• D. O₄

6. The ozone layer protects the Earth's surface from which harmful radiation?

• A. Infrared radiation
• B. Ultraviolet (UV) radiation
• C. X-rays
• D. Gamma rays

7. Which synthetic chemical compound is primarily responsible for the depletion of the ozone layer?

• A. Chlorofluorocarbons (CFCs)
• B. Carbon dioxide
• C. Methane
• D. Nitrous oxide

8. In 1987, which organization forged an agreement to freeze CFC production at 1986 levels?

• A. WHO
• B. UNEP
• C. UNESCO
• D. WWF

9. The phenomenon of progressive accumulation of non-biodegradable toxic chemicals at each successive trophic level is known as:

• A. Eutrophication
• B. Biological Magnification
• C. Bio-degradation
• D. Bio-accumulation

10. In a food chain consisting of Grass → Deer → Tiger, which organism will have the maximum concentration of harmful non-biodegradable chemicals?

• A. Grass
• B. Deer
• C. Tiger
• D. Equal in all three

11. Decomposers in an ecosystem are responsible for:

• A. Converting organic matter into inorganic substances
• B. Converting inorganic substance into organic matter
• C. Converting solar energy into chemical energy
• D. Fixing atmospheric nitrogen into plants

12. Which of the following forms an artificial (man-made) ecosystem?

• A. Forest
• B. Lake
• C. Crop field
• D. Pond

13. Movement of energy in an ecosystem is always:

• A. Unidirectional
• B. Bidirectional
• C. Multidirectional
• D. Cyclic

14. What are the biotic components of an ecosystem?

• A. Temperature, water, and soil
• B. Air, sunlight, and minerals
• C. Plants, animals, and microorganisms
• D. Rainfall and humidity

15. The network of interconnected food chains operating in an ecosystem is called a:

• A. Food web
• B. Trophic system
• C. Ecological pyramid
• D. Ecosystem cycle

16. Ozone is formed at higher levels of the atmosphere by the action of UV rays on:

• A. Oxygen molecules (O₂)
• B. Carbon dioxide (CO₂)
• C. Nitrogen gas (N₂)
• D. Water vapor (H₂O)

17. Which of the following is a non-biodegradable pollutant?

• A. Vegetable peels
• B. Paper
• C. Plastic bag
• D. Animal dung

18. The first trophic level in any food chain is always represented by:

• A. Primary consumers
• B. Producers
• C. Decomposers
• D. Secondary consumers

19. If 20,000 J of energy is available at the producer level, how much energy will be available to secondary consumers?

• A. 2,000 J
• B. 200 J
• C. 20 J
• D. 2 J

20. Disposable kulhads (clay cups) were replaced by paper cups in trains primarily because:

• A. Paper cups are cheaper to produce
• B. Making clay cups on a large scale causes loss of fertile topsoil
• C. Clay cups are harmful to health
• D. Paper cups hold hot tea longer

21. Carnivores occupying the third trophic level are classified as:

• A. Producers
• B. Primary consumers
• C. Secondary consumers
• D. Decomposers

22. Which of the following statements about food chains is FALSE?

• A. Food chains usually consist of 3 to 4 steps
• B. Energy flow is circular and reversible
• C. Loss of energy occurs at each step
• D. Producers are at the first trophic level

23. Microorganisms like bacteria and fungi are called decomposers because they:

• A. Produce complex organic matter
• B. Break down complex organic matter into simple inorganic substances
• C. Synthesize food in the presence of sunlight
• D. Consume live animals

24. What happens if all decomposers are completely removed from an ecosystem?

• A. Herbivores will increase rapidly
• B. Dead remains will accumulate and nutrient cycling will stop
• C. Producers will grow much faster
• D. Energy flow will increase

25. Accumulation of non-biodegradable waste in environment causes:

• A. Enrichment of soil fertility
• B. Environmental pollution and ecological imbalance
• C. Rapid increase in biodiversity
• D. Increase in atmospheric oxygen

26. Which chemical reaction represents the formation of ozone in the upper atmosphere?

• A. O₂ + UV → O + O, and O + O₂ → O₃
• B. O₂ + O₂ → O₄
• C. H₂O + O₂ → O₃ + H₂
• D. CO₂ + O → O₃ + C

27. Human beings occupy which position in any food chain?

• A. Only Producers
• B. Only Primary Consumers
• C. Omnivores at Top Trophic Levels
• D. Decomposers

28. Which of the following is an abiotic component of an ecosystem?

• A. Bacteria
• B. Fungi
• C. Temperature
• D. Earthworms

29. Why are food chains generally limited to 3 or 4 trophic levels?

• A. Organisms run out of space
• B. Very little usable energy remains available after 3-4 levels
• C. Top carnivores stop reproducing
• D. Decomposers eat all energy at 4th level

30. An aquarium needs regular cleaning, whereas a natural pond does not. Why?

• A. Aquariums have more decomposers than ponds
• B. Aquarium is an incomplete artificial ecosystem with lack of natural decomposers
• C. Fish in aquariums produce more waste
• D. Ponds do not contain fish