Ecosystem
1. An ecosystem consists of:
(A) Only living organisms
(B) Only non-living components
(C) Living organisms and their physical environment
(D) Only plants and animals
Answer: (C) Living organisms and their physical environment
Explanation: An ecosystem includes biotic components and abiotic factors such as water, soil, air, light and temperature.
2. Which of the following is an abiotic component of an ecosystem?
(A) Grass
(B) Bacteria
(C) Sunlight
(D) Deer
Answer: (C) Sunlight
3. Which organisms form the first trophic level in a typical ecosystem?
(A) Herbivores
(B) Carnivores
(C) Producers
(D) Decomposers
Answer: (C) Producers
4. The primary source of energy for most ecosystems is:
(A) Soil
(B) Sunlight
(C) Water
(D) Oxygen
Answer: (B) Sunlight
Food Chain & Food Web
5. Which sequence represents a correct food chain?
(A) Grass → Deer → Tiger
(B) Tiger → Deer → Grass
(C) Deer → Grass → Tiger
(D) Grass → Tiger → Deer
Answer: (A) Grass → Deer → Tiger
6. In the food chain Grass → Grasshopper → Frog → Snake, the frog is a:
(A) Producer
(B) Primary consumer
(C) Secondary consumer
(D) Decomposer
Answer: (C) Secondary consumer
7. A food web differs from a food chain because a food web:
(A) Contains only producers
(B) Shows multiple interconnected food chains
(C) Contains no consumers
(D) Shows only one feeding relationship
Answer: (B) Shows multiple interconnected food chains
8. Energy flow through an ecosystem is generally:
(A) Cyclic
(B) One-way
(C) Random
(D) Reversible
Answer: (B) One-way
9. If the population of producers decreases drastically, which group is likely to be affected first?
(A) Primary consumers
(B) Decomposers only
(C) Abiotic factors
(D) Sunlight
Answer: (A) Primary consumers
Producers, Consumers & Decomposers
10. Green plants are called producers because they:
(A) Consume other organisms
(B) Produce organic food using light energy
(C) Decompose dead matter
(D) Consume oxygen only
Answer: (B) Produce organic food using light energy
11. Animals that feed directly on plants are called:
(A) Primary consumers
(B) Secondary consumers
(C) Decomposers
(D) Producers
Answer: (A) Primary consumers
12. Which organism is a decomposer?
(A) Tiger
(B) Grass
(C) Mushroom
(D) Deer
Answer: (C) Mushroom
13. The major role of decomposers in an ecosystem is to:
(A) Produce sunlight
(B) Break down dead organic matter and recycle nutrients
(C) Consume only living plants
(D) Increase atmospheric oxygen directly
Answer: (B) Break down dead organic matter and recycle nutrients
Ecological Pyramids
14. The pyramid that represents the amount of energy available at different trophic levels is the:
(A) Pyramid of numbers
(B) Pyramid of biomass
(C) Pyramid of energy
(D) Pyramid of population
Answer: (C) Pyramid of energy
15. The pyramid of energy is always:
(A) Inverted
(B) Upright
(C) Circular
(D) Irregular
Answer: (B) Upright
16. Approximately what percentage of energy is generally transferred from one trophic level to the next?
(A) 1%
(B) 10%
(C) 50%
(D) 90%
Answer: (B) 10%
Explanation: The “10% law” is a useful ecological approximation: roughly 10% of energy at one trophic level is transferred to the next.
17. Which trophic level generally contains the greatest amount of available energy?
(A) Producers
(B) Primary consumers
(C) Secondary consumers
(D) Tertiary consumers
Answer: (A) Producers
Biodiversity
18. Biodiversity refers to:
(A) Only the number of animal species
(B) Variety of life at genetic, species and ecosystem levels
(C) Only plant diversity
(D) Only ecosystem size
Answer: (B) Variety of life at genetic, species and ecosystem levels
19. Which region is generally considered highly rich in biodiversity?
(A) Polar ice caps
(B) Tropical rainforests
(C) Deserts only
(D) Deep-freeze environments
Answer: (B) Tropical rainforests
20. A species found naturally only in a particular geographical region is called:
(A) Exotic
(B) Endemic
(C) Migratory
(D) Cosmopolitan
Answer: (B) Endemic
Conservation
21. Conservation of biodiversity means:
(A) Destroying habitats
(B) Protecting species, habitats and ecosystems
(C) Increasing pollution
(D) Removing all predators
Answer: (B) Protecting species, habitats and ecosystems
22. Which is an example of in-situ conservation?
(A) Zoo
(B) Botanical garden
(C) National park
(D) Seed bank
Answer: (C) National park
Explanation: In-situ conservation protects organisms in their natural habitats.
23. Which is an example of ex-situ conservation?
(A) Wildlife sanctuary
(B) National park
(C) Biosphere reserve
(D) Zoo
Answer: (D) Zoo
24. The Red Data Book primarily contains information about:
(A) Weather conditions
(B) Threatened species
(C) Soil types
(D) Agricultural crops only
Answer: (B) Threatened species
Adaptation
25. The thick fur and layer of body fat in polar animals are adaptations mainly for:
(A) Increasing water loss
(B) Preventing heat loss
(C) Increasing photosynthesis
(D) Improving digestion
Answer: (B) Preventing heat loss
26. The hump of a camel is primarily associated with storage of:
(A) Water
(B) Fat
(C) Protein
(D) Oxygen
Answer: (B) Fat
27. Which adaptation helps cactus plants survive in dry environments?
(A) Broad leaves
(B) Leaves modified into spines
(C) Thin roots only
(D) Large water-losing leaves
Answer: (B) Leaves modified into spines
Pollution
28. Excessive nutrients entering a lake or pond can cause:
(A) Eutrophication
(B) Desertification
(C) Deforestation
(D) Biomagnification only
Answer: (A) Eutrophication
29. The accumulation of certain toxic substances at increasingly higher concentrations along a food chain is called:
(A) Eutrophication
(B) Biomagnification
(C) Nitrogen fixation
(D) Decomposition
Answer: (B) Biomagnification
30. Which of the following is correctly matched?
(A) CFCs — Ozone depletion
(B) Excess nutrients — Eutrophication
(C) Persistent pollutants — Biomagnification
(D) All of the above
Answer: (D) All of the above
Must-Memorize Ecology Associations
| Topic | Key Fact |
|---|---|
| Ecosystem | Biotic + abiotic components |
| Main energy source | Sun |
| 1st trophic level | Producers |
| Primary consumers | Herbivores |
| Secondary consumers | Feed on primary consumers |
| Decomposers | Break down dead organic matter |
| Food chain | Linear feeding relationship |
| Food web | Interconnected food chains |
| Energy flow | One-way |
| Energy transfer | ~10% between trophic levels |
| Pyramid of energy | Always upright |
| Biodiversity | Variety of life |
| Endemic species | Restricted naturally to a particular region |
| In-situ conservation | National park, sanctuary |
| Ex-situ conservation | Zoo, botanical garden, seed bank |
| Red Data Book | Threatened species |
| Camel | Desert adaptation |
| Cactus | Leaves modified into spines |
| Polar animals | Thick fur/fat for insulation |
| Biomagnification | Toxin concentration increases along food chain |
| Eutrophication | Excess nutrients → algal growth → oxygen depletion |
| CFCs | Ozone depletion |
Application-Based Questions to Remember
Grass → Deer → Tiger → Food chain
Multiple interconnected food chains → Food web
Grass → Producer
Deer → Primary consumer
Tiger → Higher-level consumer
Mushroom/Bacteria → Decomposer
Sun → Main energy source
Energy transfer → ~10%
Energy pyramid → Always upright
National park → In-situ conservation
Zoo → Ex-situ conservation
Species restricted to one region → Endemic
Cactus spines → Reduce water loss/defence
Camel hump → Fat storage
Toxic chemicals increasing up food chain → Biomagnification
Nutrient enrichment of water → Eutrophication