CBSE Class 12 Biology Short Answer Questions – Biodiversity and Conservation (NCERT Based)

Unit V: Ecology and Environment | Chapter 15: Biodiversity and Conservation

CBSE Class 12 Biology Chapter 15 Short Answer Questions – Biodiversity and Conservation (NCERT)

Course & Examination Details

• Course: CBSE Class 12 Biology
• Unit: Unit V – Ecology and Environment
• Chapter: Chapter 15 – Biodiversity and Conservation
• Board: Central Board of Secondary Education (CBSE)
• Syllabus Base: Strictly as per NCERT Textbook
• Exam Relevance: CBSE Class 12 Board Examinations (2–3 Mark Questions)

Short Answer Type Questions (60–80 Words Each)

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

Section A: Biodiversity and Its Levels (Q1–Q10)

Q1. Define biodiversity and explain its significance.

Ans:
Biodiversity refers to the total variety of life forms present on Earth, including plants, animals, and microorganisms. It is significant because it maintains ecosystem stability, supports food chains, enhances productivity, and provides resources such as food, medicines, and raw materials essential for human survival.

Q2. Explain genetic diversity with an example.

Ans:
Genetic diversity refers to variation in genes within a species. It allows populations to adapt to environmental changes and resist diseases. For example, different varieties of rice cultivated in India show genetic diversity, ensuring better crop resilience.

Q3. What is species diversity? Why is it higher in tropics?

Ans:
Species diversity refers to the variety and relative abundance of species in a given area. It is higher in tropical regions due to stable climate, longer evolutionary time, high productivity, and minimal environmental disturbances.

Q4. Describe ecosystem diversity.

Ans:
Ecosystem diversity refers to the variety of ecosystems present in a region, such as forests, grasslands, deserts, wetlands, and marine ecosystems. Each ecosystem supports unique species and ecological processes, contributing to overall biodiversity.

Q5. Differentiate between genetic and species diversity.

Ans:
Genetic diversity involves variations within a species, while species diversity refers to variety among different species in an area. Genetic diversity enhances adaptability, whereas species diversity improves ecosystem stability and resilience.

Q6. Why is India considered a mega-diverse country?

Ans:
India is considered mega-diverse because it harbors nearly 8% of global species diversity despite occupying only about 2.4% of Earth’s land area, owing to varied climates and ecosystems.

Q7. Explain species richness and species evenness.

Ans:
Species richness refers to the number of species present in an area, while species evenness refers to the relative abundance of individuals among species. Both determine overall species diversity.

Q8. How does biodiversity differ at local and global levels?

Ans:
Local biodiversity refers to species diversity within a small area, whereas global biodiversity represents total species diversity on Earth. Local diversity contributes cumulatively to global biodiversity.

Q9. What is endemism?

Ans:
Endemism refers to species restricted to a specific geographical region and not found elsewhere, such as certain plant species in the Western Ghats.

Q10. Why is biodiversity higher in tropical rainforests than temperate regions?

Ans:
Tropical rainforests experience stable climate, high rainfall, abundant sunlight, and uninterrupted evolution, leading to greater species diversification than temperate regions.

Section B: Patterns of Biodiversity (Q11–Q20)

Q11. Explain latitudinal gradient in biodiversity.

Ans:
Latitudinal gradient refers to the increase in biodiversity from poles to equator. Tropical regions show maximum biodiversity due to favorable climatic conditions and longer evolutionary history.

Q12. Describe the species–area relationship.

Ans:
Species–area relationship states that species richness increases with increasing area and is expressed as S = CAᶻ. It reflects how larger habitats support more species.

Q13. Who proposed the species–area relationship?

Ans:
Alexander von Humboldt proposed the species–area relationship based on studies in tropical forests.

Q14. Why do larger areas have higher species richness?

Ans:
Larger areas provide diverse habitats, greater resources, and reduced extinction risk, supporting higher species richness.

Q15. What does a steeper slope (Z value) indicate?

Ans:
A steeper slope indicates rapid increase in species richness with area, commonly observed in large regions like continents.

Q16. Why is biodiversity unevenly distributed on Earth?

Ans:
Uneven climate, resource availability, evolutionary history, and geographical conditions cause uneven biodiversity distribution.

Q17. Explain why islands show unique biodiversity patterns.

Ans:
Islands have isolated environments, leading to speciation and high endemism but also higher extinction risk.

Q18. What is the importance of biodiversity hotspots?

Ans:
Biodiversity hotspots contain high species richness and endemism under threat, making them conservation priorities.

Q19. Name one biodiversity hotspot in India.

Ans:
Western Ghats is a major biodiversity hotspot in India.

Q20. How does area influence extinction rates?

Ans:
Smaller areas support fewer species and face higher extinction rates due to limited resources and habitat fragmentation.

Section C: Importance of Biodiversity (Q21–Q30)

Q21. Explain the ecological importance of biodiversity.

Ans:
Biodiversity enhances ecosystem stability, resilience, nutrient cycling, pollination, soil fertility, and climate regulation.

Q22. How does biodiversity contribute to ecosystem productivity?

Ans:
Higher biodiversity improves resource utilization efficiency, leading to increased productivity and stability.

Q23. Describe the economic importance of biodiversity.

Ans:
Biodiversity provides food, medicines, timber, fuel, fibers, and genetic resources essential for agriculture and industries.

Q24. Mention medicinal importance of biodiversity.

Ans:
Many medicines, including antibiotics and anticancer drugs, are derived from plants and microorganisms.

Q25. Explain aesthetic value of biodiversity.

Ans:
Biodiversity provides recreation, tourism, and aesthetic enjoyment, enhancing mental well-being and cultural identity.

Q26. Why is biodiversity ethically important?

Ans:
Every species has intrinsic value and the right to exist, independent of human use.

Q27. How does biodiversity support agriculture?

Ans:
It provides crop varieties, pollinators, pest control, and soil microorganisms essential for sustainable farming.

Q28. Explain the role of biodiversity in climate regulation.

Ans:
Forests and oceans regulate atmospheric gases and temperature, reducing climate extremes.

Q29. Why is biodiversity essential for ecosystem resilience?

Ans:
Diverse ecosystems recover faster from disturbances due to functional redundancy among species.

Q30. How does biodiversity ensure long-term ecosystem sustainability?

Ans:
It maintains balanced interactions, nutrient cycling, and stable food webs.

Section D: Loss of Biodiversity (Q31–Q40)

Q31. What is biodiversity loss?

Ans:
Biodiversity loss refers to reduction in species numbers, genetic diversity, and ecosystem degradation.

Q32. Explain habitat loss as a cause of biodiversity loss.

Ans:
Habitat destruction due to deforestation, urbanization, and agriculture removes living spaces, leading to extinction.

Q33. What is habitat fragmentation?

Ans:
Habitat fragmentation breaks large habitats into isolated patches, reducing population size and genetic diversity.

Q34. Explain over-exploitation with an example.

Ans:
Over-exploitation involves excessive use of resources. Overfishing has led to decline of many fish species.

Q35. How do alien species threaten native biodiversity?

Ans:
Alien species outcompete native species for resources, leading to population decline or extinction.

Q36. What are co-extinctions?

Ans:
Co-extinctions occur when extinction of one species leads to extinction of dependent species.

Q37. What is the ‘Evil Quartet’?

Ans:
The Evil Quartet includes habitat loss, over-exploitation, alien species invasion, and co-extinctions.

Q38. Why is current extinction rate alarming?

Ans:
Present extinction rates are 100–1000 times higher than natural rates due to human activities.

Q39. How does climate change affect biodiversity?

Ans:
Climate change alters habitats, disrupts breeding cycles, and increases extinction risk.

Q40. Why are endemic species more vulnerable to extinction?

Ans:
Restricted distribution makes endemic species highly sensitive to habitat loss.

Section E: Biodiversity Conservation (Q41–Q50)

Q41. Define biodiversity conservation.

Ans:
Biodiversity conservation involves protection, sustainable use, and restoration of biological resources.

Q42. Explain in situ conservation.

Ans:
In situ conservation protects species in their natural habitats, conserving entire ecosystems.

Q43. Name two in situ conservation areas.

Ans:
National parks and wildlife sanctuaries.

Q44. What is a biosphere reserve?

Ans:
A biosphere reserve conserves biodiversity while allowing sustainable human activities.

Q45. Explain ex situ conservation.

Ans:
Ex situ conservation protects species outside their natural habitats through zoos, botanical gardens, and gene banks.

Q46. Why is ex situ conservation important?

Ans:
It protects endangered species from immediate threats and supports breeding programs.

Q47. Differentiate between in situ and ex situ conservation.

Ans:
In situ conserves species in natural habitats, while ex situ conserves them outside natural environments.

Q48. What are seed banks?

Ans:
Seed banks store seeds for long-term conservation and future use.

Q49. How can individuals contribute to biodiversity conservation?

Ans:
By sustainable resource use, reducing pollution, and supporting conservation efforts.

Q50. Why is biodiversity conservation necessary for future generations?

Ans:
It ensures ecological balance, resource availability, and survival of life on Earth.

CBSE Exam Note

These short answer questions (2–3 marks) are ideal for CBSE Class 12 board exams, ensuring concept clarity, structured answers, and strict NCERT alignment.