CBSE Class 12 Biology Very Short Answer Questions – Ecosystem (NCERT Based)

Unit V: Ecology and Environment | Chapter 14: Ecosystem

CBSE Class 12 Biology Chapter 14 Very Short Answer Questions – Ecosystem (NCERT)

Course & Examination Details

• Course: CBSE Class 12 Biology
• Unit: Unit V – Ecology and Environment
• Chapter: Chapter 14 – Ecosystem
• Board: Central Board of Secondary Education (CBSE)
• Syllabus: Strictly as per NCERT Textbook
• Usefulness: CBSE Board Exams, School Tests, Rapid Revision

Very Short Answer Type Questions (20–30 Words Each)

(Prepared strictly according to NCERT syllabus and CBSE answer-writing standards)

Section A: Ecosystem – Structure and Function (Q1–Q8)

Q1. What is an ecosystem?
Ans: An ecosystem is a functional unit of nature where living organisms interact with each other and with the physical environment.

Q2. Name the two main components of an ecosystem.
Ans: The two main components are biotic components and abiotic components.

Q3. What are abiotic components of an ecosystem?
Ans: Abiotic components include non-living factors such as light, temperature, water, soil, and nutrients.

Q4. Who are producers in an ecosystem?
Ans: Producers are autotrophic organisms like green plants that synthesize food using sunlight through photosynthesis.

Q5. Define consumers.
Ans: Consumers are heterotrophic organisms that depend directly or indirectly on producers for food.

Q6. What role do decomposers play in an ecosystem?
Ans: Decomposers break down dead organic matter into simpler inorganic substances, recycling nutrients.

Q7. Name the functional aspects of an ecosystem.
Ans: Productivity, decomposition, energy flow, and nutrient cycling are functional aspects of ecosystems.

Q8. Give one example of a natural ecosystem.
Ans: Forest ecosystem is an example of a natural ecosystem.

Section B: Productivity (Q9–Q14)

Q9. What is primary productivity?
Ans: Primary productivity is the rate at which producers synthesize organic matter using sunlight.

Q10. Define Gross Primary Productivity (GPP).
Ans: GPP is the total rate of photosynthesis in an ecosystem.

Q11. What is Net Primary Productivity (NPP)?
Ans: NPP is the rate of biomass accumulation after subtracting respiratory losses from GPP.

Q12. Write the formula for NPP.
Ans: NPP equals GPP minus respiration losses of producers.

Q13. What is secondary productivity?
Ans: Secondary productivity is the rate of formation of new biomass by consumers.

Q14. In what units is primary productivity expressed?
Ans: Primary productivity is expressed as mass per unit area per unit time.

Section C: Decomposition (Q15–Q21)

Q15. What is decomposition?
Ans: Decomposition is the breakdown of dead organic matter into simpler inorganic substances by decomposers.

Q16. Name the first step of decomposition.
Ans: Fragmentation is the first step of decomposition.

Q17. What is humification?
Ans: Humification is the formation of dark-colored, partially decomposed organic matter called humus.

Q18. What is mineralisation?
Ans: Mineralisation is the release of inorganic nutrients from organic matter during decomposition.

Q19. Name two decomposers.
Ans: Bacteria and fungi are common decomposers.

Q20. Which climatic conditions favor decomposition?
Ans: Warm and moist conditions favor rapid decomposition.

Q21. Why is decomposition slow in cold regions?
Ans: Low temperature reduces microbial activity, slowing decomposition.

Section D: Energy Flow (Q22–Q28)

Q22. How does energy enter an ecosystem?
Ans: Energy enters an ecosystem through sunlight captured by producers.

Q23. Is energy flow in an ecosystem cyclic or unidirectional?
Ans: Energy flow in an ecosystem is unidirectional.

Q24. What is the ten percent law?
Ans: Only about 10% of energy is transferred from one trophic level to the next.

Q25. What is a food chain?
Ans: A food chain is a linear sequence showing transfer of energy from producers to consumers.

Q26. What is a food web?
Ans: A food web is a network of interconnected food chains in an ecosystem.

Q27. Why are food webs important?
Ans: Food webs provide stability and alternative energy pathways in ecosystems.

Q28. Which trophic level has maximum energy?
Ans: Producers have the maximum amount of energy.

Section E: Ecological Pyramids (Q29–Q34)

Q29. What are ecological pyramids?
Ans: Ecological pyramids graphically represent trophic structure in terms of number, biomass, or energy.

Q30. Name the three types of ecological pyramids.
Ans: Pyramid of number, pyramid of biomass, and pyramid of energy.

Q31. Which ecological pyramid is always upright?
Ans: Pyramid of energy is always upright.

Q32. Why can pyramid of biomass be inverted?
Ans: In aquatic ecosystems, producers have less biomass than consumers, causing inversion.

Q33. What does pyramid of number represent?
Ans: It represents the number of individuals at each trophic level.

Q34. Which pyramid best reflects ecosystem functioning?
Ans: Pyramid of energy best reflects ecosystem functioning.

Section F: Nutrient Cycles (Q35–Q41)

Q35. What are nutrient cycles?
Ans: Nutrient cycles describe movement of nutrients through biotic and abiotic components of ecosystems.

Q36. Name two gaseous nutrient cycles.
Ans: Carbon cycle and nitrogen cycle are gaseous cycles.

Q37. Which nutrient cycle lacks a gaseous phase?
Ans: Phosphorus cycle lacks a gaseous phase.

Q38. Why is nitrogen important for living organisms?
Ans: Nitrogen is essential for synthesis of proteins, nucleic acids, and enzymes.

Q39. What is nitrogen fixation?
Ans: Nitrogen fixation converts atmospheric nitrogen into usable forms like ammonia.

Q40. Name one process that releases carbon dioxide into atmosphere.
Ans: Respiration releases carbon dioxide into the atmosphere.

Q41. Why are nutrient cycles important?
Ans: Nutrient cycles ensure continuous availability of essential elements.

Section G: Ecological Succession (Q42–Q46)

Q42. What is ecological succession?
Ans: Ecological succession is the gradual and predictable change in species composition over time.

Q43. Define primary succession.
Ans: Primary succession occurs on barren areas where no life existed earlier.

Q44. What is secondary succession?
Ans: Secondary succession occurs in areas where vegetation existed previously but was destroyed.

Q45. Name the final stable stage of succession.
Ans: Climax community is the final stable stage.

Q46. Which succession is faster: primary or secondary?
Ans: Secondary succession is faster.

Section H: Ecosystem Services (Q47–Q50)

Q47. What are ecosystem services?
Ans: Ecosystem services are benefits humans obtain from ecosystems.

Q48. Name one provisioning service.
Ans: Food supply is a provisioning ecosystem service.

Q49. Give one regulating ecosystem service.
Ans: Climate regulation is a regulating service.

Q50. Why are ecosystem services important?
Ans: Ecosystem services support human survival, economy, and environmental stability.

CBSE Exam Note

These very short answer questions (1-mark) are ideal for quick revision, concept clarity, and CBSE board exam preparation, strictly aligned with NCERT Biology Chapter 14 – Ecosystem.