Biodiversity and Conservation — Class 12 Biology NCERT Solutions (Free)
Free step-by-step NCERT solutions for Class 12 Biology chapter "Biodiversity and Conservation" — 8 important questions with detailed answers for CBSE board exam preparation.
TL;DR: Free step-by-step NCERT solutions for Class 12 Biology chapter "Biodiversity and Conservation" — 8 important questions with detailed answers for CBSE…
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NCERT Solutions for Class 12 Biology — Biodiversity and Conservation. Step-by-step answers to all 8 textbook questions from this chapter, written for CBSE board preparation and free to use.
Biodiversity and Conservation — All 8 Questions Solved
Q1. Define biodiversity. What are its levels?
Biodiversity (biological diversity) is the variety of life forms present in a given area. It encompasses genetic, species, and ecosystem diversity at different scales.
Q2. What is species diversity? Explain alpha, beta, and gamma diversity.
Species diversity is variety of different species in an area. Measured using species richness and evenness metrics.
Q3. What are hotspots of biodiversity? Name biodiversity hotspots in India.
Biodiversity hotspots are regions with exceptionally high species diversity and endemism, prioritized for conservation efforts.
Q4. Define endangered species and threatened species. Give examples from India.
Endangered species are populations at risk of extinction in near future. Threatened species include vulnerable, endangered, and critically endangered categories.
Q5. Explain habitat loss, poaching, and pollution as threats to biodiversity.
These are major causes of biodiversity loss affecting species survival and ecosystem functioning globally.
Q6. What are in-situ and ex-situ conservation? Give examples of each.
In-situ conservation protects species in natural habitats through protected areas. Ex-situ conservation maintains species outside natural habitats in zoos and botanical gardens.
Q7. What are biosphere reserves? Describe structure and function of Indian biosphere reserves.
Biosphere reserves are protected areas designated to conserve biodiversity and promote sustainable development combining protection with sustainable use.
Q8. What is CITES? How does it regulate wildlife trade and protect endangered species?
CITES (Convention on International Trade in Endangered Species) is international agreement regulating trade in endangered plants and animals to ensure species survival.
Biodiversity and Conservation — Practice MCQs with Answers
Attempt these 20 multiple-choice questions after working through the solutions above. Each carries the correct option and the reasoning behind it, so a wrong answer tells you which idea to revisit.
MCQ 1. What level of biodiversity refers to the variation in genes within a single species?
- A. Ecosystem diversity
- B. Species diversity
- C. Genetic diversity
- D. Community diversity
Answer: C. Genetic diversity — Genetic diversity is the diversity in the number and types of genes as well as chromosomes present in different species and also in the individuals of the same species.
MCQ 2. Which of the following statements is generally true regarding latitudinal gradients in biodiversity?
- A. Biodiversity decreases as one moves from poles to the equator
- B. Biodiversity increases as one moves from poles to the equator
- C. Biodiversity is highest at temperate regions
- D. Latitudinal gradients have no correlation with species diversity
Answer: B. Biodiversity increases as one moves from poles to the equator — Species diversity generally increases as we move from the poles towards the equator. Tropical regions, for example, harbour more species than temperate or polar regions.
MCQ 3. According to current estimates in NCERT, how many biodiversity hotspots are present globally?
- A. 18
- B. 25
- C. 34
- D. 42
Answer: C. 34 — Biodiversity hotspots are regions with very high levels of species richness and high degree of endemism. Globally, 34 such hotspots have been identified.
MCQ 4. Which of the following is NOT one of the 'Evil Quartet' causes for biodiversity loss?
- A. Habitat loss and fragmentation
- B. Over-exploitation
- C. Alien species invasion
- D. Gene banks
Answer: D. Gene banks — The 'Evil Quartet' comprises four major causes of biodiversity loss: habitat loss and fragmentation, over-exploitation, alien species invasions, and co-extinctions. Gene banks are a method of ex-situ conservation, not a cause of loss.
MCQ 5. Which invasive species, introduced into Indian waters (or Lake Victoria example from NCERT), has caused environmental damage by threatening native fish populations?
- A. Parthenium
- B. Eichhornia crassipes
- C. Lantana camara
- D. Nile Perch
Answer: D. Nile Perch — The introduction of Nile Perch into Lake Victoria in East Africa led to the extinction of more than 200 species of cichlid fish. The other options are invasive plant species.
MCQ 6. Which of the following is an example of ex-situ conservation?
- A. National Parks
- B. Wildlife Sanctuaries
- C. Botanical Gardens
- D. Biosphere Reserves
Answer: C. Botanical Gardens — Ex-situ conservation involves protecting endangered species outside their natural habitats, such as in botanical gardens, zoos, and seed banks. The other options are forms of in-situ conservation.
MCQ 7. Sacred groves are excellent examples of:
- A. In-situ conservation
- B. Ex-situ conservation
- C. Gene bank conservation
- D. Botanical garden conservation
Answer: A. In-situ conservation — Sacred groves are tracts of forest preserved by indigenous communities due to religious or cultural beliefs, making them a form of in-situ conservation where species are protected in their natural habitat.
MCQ 8. In the equation log S = log C + Z log A, where S = species richness, A = area, and C is a constant, what does Z represent?
- A. Slope of the regression
- B. Y-intercept
- C. Species diversity index
- D. Area exponent
Answer: A. Slope of the regression — The Z-value in the species-area relationship equation (log S = log C + Z log A) is the slope of the regression line, which indicates how species richness changes with increasing area.
MCQ 9. How many mass extinctions has the Earth experienced prior to the current ongoing sixth extinction?
- A. 2
- B. 3
- C. 5
- D. 7
Answer: C. 5 — Earth has experienced five episodes of mass extinction in the past, but the current sixth extinction is proceeding at a much faster rate, largely due to human activities.
MCQ 10. Which of the following is a direct utilitarian benefit derived from biodiversity?
- A. Aesthetic pleasure
- B. Pollination of crops
- C. Intrinsic value of species
- D. Ethical responsibility
Answer: B. Pollination of crops — Direct utilitarian benefits include economic gains like food, medicines, industrial products, and ecosystem services such as pollination, which directly benefit humans. Aesthetic pleasure and ethical responsibility fall under broader utilitarian and ethical arguments.
MCQ 11. What characteristic defines a species as 'endemic' to a particular region?
- A. It is found only in that specific region
- B. It is a migratory species
- C. It has a very large global population
- D. It has been recently introduced to that region
Answer: A. It is found only in that specific region — Endemic species are those that are native to and restricted to a particular geographical region, making them particularly vulnerable to habitat loss in that area.
MCQ 12. Which IUCN Red List category indicates that a species is facing an extremely high risk of extinction in the wild in the immediate future?
- A. Vulnerable
- B. Endangered
- C. Critically Endangered
- D. Near Threatened
Answer: C. Critically Endangered — The IUCN Red List categorizes species based on their risk of extinction. Critically Endangered denotes the highest risk of extinction in the wild, followed by Endangered and then Vulnerable.
MCQ 13. Which of the following is NOT a biodiversity hotspot located in India?
- A. Western Ghats
- B. Indo-Burma Region
- C. Himalayas
- D. Eastern Ghats
Answer: D. Eastern Ghats — India has three major biodiversity hotspots: the Western Ghats, the Eastern Himalayas (part of the Himalayas), and the Indo-Burma region. The Eastern Ghats are not designated as a global biodiversity hotspot.
MCQ 14. The Amazon rainforest is often referred to as the 'lungs of the planet' because of its immense contribution to:
- A. Soil fertility
- B. Oxygen production
- C. Water purification
- D. Mineral resources
Answer: B. Oxygen production — The Amazon rainforest, being the largest rainforest in the world, harbors an immense number of plant species that contribute significantly to global oxygen production through photosynthesis.
MCQ 15. Paul Ehrlich's 'Rivet Popper Hypothesis' is used to explain the importance of:
- A. Gene banks
- B. Species-area relationship
- C. Ecosystem stability
- D. Alien species invasion
Answer: C. Ecosystem stability — The Rivet Popper Hypothesis illustrates how the loss of even a few species (rivets) can weaken an ecosystem (aeroplane) and eventually lead to its collapse, emphasizing the importance of biodiversity for ecosystem stability.
MCQ 16. What is meant by 'co-extinction'?
- A. Extinction of a species due to over-exploitation
- B. Extinction of a species due to climate change
- C. Extinction of a species leading to the extinction of another species dependent on it
- D. Extinction of all species in a given habitat simultaneously
Answer: C. Extinction of a species leading to the extinction of another species dependent on it — Co-extinction occurs when the extinction of one species, typically a host or a pollinator, inevitably leads to the extinction of another species that is obligately associated with it.
MCQ 17. Despite its land area being only 2.4% of the world's total, India accounts for what percentage of global species diversity?
- A. 0.8%
- B. 2.4%
- C. 8.1%
- D. 12.5%
Answer: C. 8.1% — India is one of the 12 mega diversity countries in the world, known for its rich biodiversity, contributing approximately 8.1% of the global species diversity.
MCQ 18. The core zone of a Biosphere Reserve is designated for:
- A. Human settlement and tourism
- B. Research and educational activities
- C. Strict protection of wildlife and natural processes
- D. Controlled harvesting of resources
Answer: C. Strict protection of wildlife and natural processes — Biosphere Reserves are typically zoned: the core zone is strictly protected for wildlife, the buffer zone allows for research and education, and the transition zone permits sustainable human activities.
MCQ 19. Cryopreservation is a technique used for ex-situ conservation where biological materials are preserved at ultra-low temperatures, typically:
- A. 0°C
- B. -4°C
- C. -80°C
- D. -196°C
Answer: D. -196°C — Cryopreservation involves storing viable biological materials, such as gametes, pollen, or seeds, in liquid nitrogen at a temperature of -196°C to maintain their viability for long periods.
MCQ 20. The 'Earth Summit' held in Rio de Janeiro in 1992 was primarily focused on:
- A. Reducing greenhouse gas emissions
- B. Conservation of biodiversity and sustainable use of its components
- C. Nuclear disarmament
- D. Eradicating global poverty
Answer: B. Conservation of biodiversity and sustainable use of its components — The Earth Summit (Rio Summit) in 1992 led to the Convention on Biological Diversity (CBD), addressing the conservation and sustainable use of biological diversity.
How to Use These Solutions
Attempt each question yourself first and only then compare with the worked answer. Marks in the CBSE board exam are awarded for the METHOD as much as the final result, so reproduce the steps rather than memorising the last line. Where a solution states a law, a formula or a definition, learn that wording — examiners look for it.
Related practice for this chapter: chapter MCQs, previous-year questions, revision notes and sample papers.