Question Bank — Biodiversity and Conservation

NCERT Class 12 Biology · Chapter 13 · CBSE Board Pattern

Class 12 Biology Chapter 13 Question Bank CBSE Board Pattern

QUESTION BANK

Chapter: Biodiversity and Conservation (NCERT Class 12)

Section A — MCQs (10 questions, 1 mark each)

  1. Which of the following represents the correct order of biodiversity levels as described in the chapter?
    (a) Genetic → Species → Ecological
    (b) Species → Genetic → Ecological
    (c) Ecological → Genetic → Species
    (d) Genetic → Ecological → Species

  2. According to Robert May’s estimate mentioned in the chapter, the global species diversity is approximately:
    (a) 1.5 million (b) 7 million (c) 20 million (d) 50 million

  3. The slope (Z) of the species-area relationship for small areas such as islands or countries lies in the range of:
    (a) 0.1 – 0.2 (b) 0.3 – 0.5 (c) 0.6 – 0.8 (d) 1.0 – 1.2

  4. Which of the following is not one of the four major causes of biodiversity loss collectively called the “Evil Quartet”?
    (a) Habitat loss and fragmentation (b) Over-exploitation
    (c) Co-extinctions (d) Climate change

  5. The Amazon rainforest is referred to in the chapter as:
    (a) “Lungs of the planet” (b) “Biodiversity hotspot of Asia”
    (c) “Sacred grove of South America” (d) “Centre of origin of angiosperms”

Assertion-Reason Questions

  1. Assertion (A): Tropical regions show greater species diversity than temperate regions.
    Reason (R): Tropical latitudes have remained relatively undisturbed for millions of years, allowing longer evolutionary time for species diversification.
    (a) Both A and R are true and R is the correct explanation of A
    (b) Both A and R are true but R is not the correct explanation of A
    (c) A is true but R is false
    (d) A is false but R is true

  2. Assertion (A): India is one of the 12 mega-diversity countries of the world.
    Reason (R): India has 2.4 % of the world’s land area but accounts for 8.1 % of global species diversity.
    (a) Both A and R are true and R is the correct explanation of A
    (b) Both A and R are true but R is not the correct explanation of A
    (c) A is true but R is false
    (d) A is false but R is true

  3. The “rivet popper hypothesis” proposed by Paul Ehrlich compares species in an ecosystem to:
    (a) Trees in a forest (b) Rivets in an aeroplane
    (c) Books in a library (d) Genes in a genome

  4. Which of the following is an example of ex situ conservation?
    (a) Biosphere reserves (b) National parks
    (c) Cryopreservation of gametes (d) Sacred groves

  5. The number of biodiversity hotspots identified in the world at present is:
    (a) 25 (b) 34 (c) 14 (d) 90

Section B — Very Short Answer (6 questions, 2 marks each)

  1. Differentiate between genetic diversity and species diversity with one example of each from the chapter.

  2. State the equation that describes the species-area relationship on a logarithmic scale. What does the symbol ‘Z’ represent?

  3. What are sacred groves? Name any two regions in India where they are found.

  4. List the three hypotheses proposed by ecologists to explain why tropics harbour greater biodiversity.

  5. Name the three categories of reasons given in the chapter for conserving biodiversity.

  6. What is meant by the “Sixth Extinction”? How does its rate compare with earlier mass extinctions?

Section C — Short Answer (5 questions, 3 marks each)

  1. Explain the three levels of biodiversity with suitable examples from India.

  2. Describe the species-area relationship observed by Alexander von Humboldt. Why are the slopes steeper when very large areas such as continents are considered?

  3. What are the major causes of biodiversity loss? Briefly explain any three causes with examples.

  4. Distinguish between narrowly utilitarian and broadly utilitarian arguments for biodiversity conservation with one example of each.

  5. Why are amphibians considered more vulnerable to extinction than other vertebrate groups? Give reasons mentioned in the chapter.

Section D — Long Answer (3 questions, 5 marks each)

  1. (a) Describe the four major causes of biodiversity loss (the “Evil Quartet”) with one example for each.
    (b) How does habitat fragmentation affect mammals and migratory birds?

  2. Explain the importance of species diversity to the ecosystem. Describe Paul Ehrlich’s “rivet popper hypothesis” and its significance. (No diagram required)

  3. Describe the two major approaches to biodiversity conservation — in situ and ex situ — with examples.
    Draw a labelled flow chart showing the different strategies under each approach as discussed in the chapter.

Section E — Case/Source-Based (2 questions, 4 marks each)

25. Read the passage and answer the questions that follow:
“Although India has only 2.4 per cent of the world’s land area, its share of the global species diversity is an impressive 8.1 per cent… Nearly 45,000 species of plants and twice as many of animals have been recorded from India… Applying this proportion to India’s diversity figures, we estimate that there are probably more than 1,00,000 plant species and more than 3,00,000 animal species yet to be discovered…”

(i) What percentage of the world’s land area does India occupy?
(ii) How many plant and animal species have already been recorded from India?
(iii) According to the chapter, how many more plant and animal species are estimated to exist in India?
(iv) Why does the chapter describe the task of completing the inventory of India’s biological wealth as “hopeless”?

26. Read the passage and answer the questions that follow:
“When alien species are introduced unintentionally or deliberately… some of them turn invasive and cause decline or extinction of indigenous species. The Nile perch introduced into Lake Victoria… led eventually to the extinction of an ecologically unique assemblage of more than 200 species of cichlid fish… The recent illegal introduction of the African catfish Clarias gariepinus… is posing a threat to the indigenous catfishes in our rivers.”

(i) What term is used for species that are introduced into a new area and become harmful?
(ii) Name the invasive fish introduced into Lake Victoria and its impact.
(iii) Give one example of an invasive plant species mentioned in the chapter that threatens native biodiversity in India.
(iv) Why is the illegal introduction of Clarias gariepinus a matter of concern for Indian rivers?

▶ Answer Key Attempt all questions first,
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Section A

  1. (a)
  2. (b)
  3. (a)
  4. (d)
  5. (a)
  6. (a)
  7. (a)
  8. (b)
  9. (c)
  10. (b)

Section B

  1. Genetic diversity: variation within a species (e.g., 50,000 strains of rice in India) — 1 mark; Species diversity: diversity at species level (e.g., greater amphibians in Western Ghats) — 1 mark.
  2. log S = log C + Z log A; Z = slope/regression coefficient — 1 mark each.
  3. Forest tracts protected by cultural/religious traditions — 1 mark; Khasi & Jaintia Hills, Aravalli Hills, Western Ghats, Sarguja-Chanda-Bastar — any two (1 mark).
  4. (a) Longer evolutionary time (b) Less seasonal, more constant environment (c) More solar energy → higher productivity — 1 mark each.
  5. Narrowly utilitarian, broadly utilitarian, ethical — 2 marks (any order).
  6. Current mass extinction driven by human activities; rate 100–1000 times faster than pre-human times — 1 mark each.

Section C

  1. Genetic (Rauwolfia potency variation / rice strains) — 1 mark; Species (Western vs Eastern Ghats amphibians) — 1 mark; Ecological (India’s deserts, rainforests, mangroves vs Norway) — 1 mark.
  2. Species richness increases with area up to a limit; rectangular hyperbola; log scale gives straight line — 2 marks; Steeper Z (0.6–1.2) for continents because larger areas include more diverse habitats — 1 mark.
  3. Habitat loss & fragmentation, over-exploitation, alien species invasions, co-extinctions — any three with one example each (1 mark × 3).
  4. Narrowly utilitarian: direct economic benefits (medicines, food) — 1.5 marks; Broadly utilitarian: ecosystem services (pollination, oxygen, flood control) — 1.5 marks.
  5. 32 % of amphibian species face extinction threat (highest among vertebrates) — 1 mark; reasons: habitat specificity and sensitivity to environmental changes (from text implication) — 2 marks.

Section D

  1. (a) Habitat loss (Amazon deforestation), Over-exploitation (passenger pigeon), Alien species (Nile perch), Co-extinctions (host-parasite / plant-pollinator) — 4 marks; (b) Large-territory mammals and migrants affected by fragmentation — 1 mark.
  2. Stability, resistance to invasion, higher productivity (Tilman’s experiments) — 3 marks; Rivet popper analogy with explanation of key vs non-key species — 2 marks.
  3. In situ: hotspots, biosphere reserves, national parks, sanctuaries, sacred groves — 2 marks; Ex situ: zoos, botanical gardens, cryopreservation, tissue culture, seed banks — 2 marks; Labelled flow chart — 1 mark.

Section E

  1. (i) 2.4 % — 1 mark; (ii) 45,000 plants + ~90,000 animals — 1 mark; (iii) >1,00,000 plants + >3,00,000 animals — 1 mark; (iv) Species may become extinct before discovery + lack of trained taxonomists and time — 1 mark.
  2. (i) Invasive alien species — 1 mark; (ii) Nile perch → extinction of >200 cichlid species — 1 mark; (iii) Parthenium / Lantana / Eichhornia (any one) — 1 mark; (iv) Threatens indigenous catfishes through competition/predation — 1 mark.
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All questions are answerable from the NCERT chapter text. Reviewed by GFIS faculty.