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Biodiversity and Conservation

NCERT Class 12 · Biology Based on NCERT Class 12 Biology textbook · Free CBSE study kit

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Chapter Notes

Overview
This chapter explores the concept of biodiversity—the variety of life at genetic, species, and ecosystem levels—and its patterns, importance, and alarming loss due to human activities. It explains why biodiversity is critical for ecosystem stability and human survival, and details both in situ and ex situ conservation strategies. The one big idea a student must walk away with is that biodiversity is our planet's biological wealth, and its rapid loss threatens ecosystem services and our own existence, making conservation an urgent ethical and practical necessity.
Key Concepts (16)
Biodiversity
The term popularised by sociobiologist Edward Wilson to describe the combined diversity at all levels of biological organisation, ranging from macromolecules within cells to biomes.
e.g. The diversity of life forms in a tropical rainforest, including different species of trees, insects, birds, and microorganisms.
Genetic diversity
The diversity at the genetic level shown by a single species over its distributional range, including variation in genes and alleles.
e.g. The medicinal plant Rauwolfia vomitoria shows genetic variation in the potency and concentration of reserpine across different Himalayan ranges; India has over 50,000 genetically different strains of rice.
Species diversity
The diversity at the species level, referring to the number and abundance of different species in a given area.
e.g. The Western Ghats have a greater amphibian species diversity than the Eastern Ghats.
Ecological diversity
The diversity at the ecosystem level, encompassing the variety of habitats, communities, and ecological processes.
e.g. India, with its deserts, rain forests, mangroves, coral reefs, wetlands, estuaries, and alpine meadows, has greater ecosystem diversity than a Scandinavian country like Norway.
Mega diversity countries
Countries that possess exceptionally high levels of species diversity and endemism; India is one of the 12 mega diversity countries of the world.
e.g. India has only 2.4% of the world's land area but contributes 8.1% of global species diversity.
Latitudinal gradient
The pattern of species diversity decreasing as we move away from the equator towards the poles.
e.g. Colombia near the equator has nearly 1,400 species of birds, while New York at 41°N has 105 species, and Greenland at 71°N has only 56 species.
Species-Area relationship
The relationship between species richness and area, which for a wide variety of taxa turns out to be a rectangular hyperbola; on a logarithmic scale, it is a straight line described by log S = log C + Z log A.
e.g. Alexander von Humboldt observed that within a region, species richness increases with increasing explored area, but only up to a limit.
Rivet popper hypothesis
An analogy by ecologist Paul Ehrlich comparing species in an ecosystem to rivets in an airplane; losing species (popping rivets) may not immediately affect ecosystem function, but continued loss weakens the system and loss of key species (rivets on wings) is critical.
e.g. If every passenger in an airplane pops a rivet to take home, the plane becomes dangerously weak over time; similarly, losing species gradually destabilises an ecosystem.
The Evil Quartet
The four major causes of biodiversity loss due to human activities: habitat loss and fragmentation, over-exploitation, alien species invasions, and co-extinctions.
e.g. Habitat loss from deforestation, overfishing of marine fish, introduction of Nile perch in Lake Victoria, and extinction of parasites when their host fish goes extinct.
Biodiversity hotspots
Regions with very high levels of species richness and high degree of endemism, also experiencing accelerated habitat loss; strict protection of these hotspots could reduce ongoing mass extinctions by almost 30%.
e.g. Three hotspots cover India's biodiversity: Western Ghats and Sri Lanka, Indo-Burma, and Himalaya.
In situ conservation
Conservation approach where the whole ecosystem is protected, saving all biodiversity at all levels by protecting the natural habitat of organisms.
e.g. Biosphere reserves, national parks, wildlife sanctuaries, and sacred groves in India.
Ex situ conservation
Conservation approach where threatened animals and plants are taken out of their natural habitat and placed in special settings for protection and care.
e.g. Zoological parks, botanical gardens, wildlife safari parks, cryopreservation of gametes, in vitro fertilisation, tissue culture propagation, and seed banks.
Sacred groves
Tracts of forest set aside in many cultures where all trees and wildlife are venerated and given total protection, serving as last refuges for rare and threatened plants.
e.g. Found in Khasi and Jaintia Hills in Meghalaya, Aravalli Hills of Rajasthan, Western Ghat regions of Karnataka and Maharashtra, and Sarguja, Chanda, and Bastar areas of Madhya Pradesh.
Bioprospecting
Exploring molecular, genetic, and species-level diversity for products of economic importance.
e.g. Searching tropical rainforests for new medicinal compounds from plants.
Endemism
The ecological state of a species being unique to a defined geographic location, such as an island, nation, or other defined zone, and not found naturally anywhere else.
e.g. Species confined to the Western Ghats and not found elsewhere.
Co-extinctions
When a species becomes extinct, the plant and animal species associated with it in an obligatory way also become extinct.
e.g. When a host fish species becomes extinct, its unique assemblage of parasites also meets the same fate; extinction of one partner in a coevolved plant-pollinator mutualism leads to extinction of the other.
Formulas & Equations (1)
log S = log C + Z log A
Reads as: Log of species richness equals log of the Y-intercept plus Z times log of area
Variables: S = Species richness (dimensionless); A = Area (square kilometres or any unit of area); Z = Slope of the line (regression coefficient, dimensionless); C = Y-intercept (dimensionless)
Use when: When describing or calculating the species-area relationship on a logarithmic scale, or when interpreting the slope Z in exam questions about biodiversity patterns.
⚠ Students often forget that this is the log-transformed form and write S = C + ZA directly, which is incorrect. Also, they confuse Z values: Z = 0.1 to 0.2 for small areas, but Z = 0.6 to 1.2 for very large areas like continents.
How It Works
Estimating total number of species on Earth
  1. Biologists make a statistical comparison of the temperate-tropical species richness of an exhaustively studied group of insects.
  2. They extrapolate this ratio to other groups of animals and plants.
  3. Robert May's conservative estimate places global species diversity at about 7 million.
  4. Currently, only about 1.5 million species have been described (IUCN 2004).
💡 The estimate is an educated guess; extreme estimates range from 20 to 50 million, but the scientifically sound estimate by Robert May is 7 million. Students often quote the extreme range without mentioning May's estimate.
Patterns of Biodiversity: Latitudinal Gradient
  1. Species diversity is highest near the equator and decreases towards the poles.
  2. Tropics (23.5°N to 23.5°S) harbour more species than temperate or polar areas.
  3. Hypotheses: (a) Tropical regions have had a long evolutionary time for species diversification due to fewer glaciations. (b) Tropical environments are less seasonal, more constant and predictable, promoting niche specialisation. (c) More solar energy in tropics contributes to higher productivity, indirectly increasing diversity.
💡 All three hypotheses are important for board exams. Students often miss the 'long evolutionary time' point and only mention productivity.
Species-Area Relationship
  1. Within a region, species richness increases with increasing explored area, but only up to a limit.
  2. The relationship is a rectangular hyperbola.
  3. On a logarithmic scale, it becomes a straight line: log S = log C + Z log A.
  4. For small areas, Z lies in the range of 0.1 to 0.2 regardless of taxonomic group or region.
  5. For very large areas like entire continents, Z values are steeper, ranging from 0.6 to 1.2.
💡 The slope Z is steeper for larger areas. Students often confuse the Z values for small vs. large areas. The example of frugivorous birds and mammals in tropical forests gives Z = 1.15.
Loss of Biodiversity: Causes (The Evil Quartet)
  1. Habitat loss and fragmentation: Most important cause; tropical rainforests reduced from >14% to <6% of land surface; degradation by pollution; fragmentation affects large mammals and migratory species.
  2. Over-exploitation: When human 'need' turns to 'greed'; examples include Steller's sea cow, passenger pigeon, and overharvesting of marine fish.
  3. Alien species invasions: Introduced species turn invasive and cause decline/extinction of indigenous species; examples: Nile perch in Lake Victoria (extinction of 200+ cichlid species), carrot grass (Parthenium), Lantana, water hyacinth (Eicchornia), African catfish Clarias gariepinus in Indian rivers.
  4. Co-extinctions: Obligatory associations lead to extinction of dependent species when host species goes extinct; e.g., host fish and its parasites, coevolved plant-pollinator mutualisms.
💡 Habitat loss is the most important cause. The Nile perch example is classic for alien species invasions. Students often forget co-extinctions as a separate cause.
Biodiversity Conservation: In situ and Ex situ
  1. In situ conservation: Protect whole ecosystems to save biodiversity at all levels. Examples: biosphere reserves (14 in India), national parks (90), wildlife sanctuaries (448), sacred groves.
  2. Biodiversity hotspots: 34 globally; three in India (Western Ghats and Sri Lanka, Indo-Burma, Himalaya); cover <2% of earth's land area but harbour extremely high species numbers; strict protection could reduce mass extinctions by ~30%.
  3. Ex situ conservation: Remove threatened species from natural habitat for special care. Methods: zoological parks, botanical gardens, wildlife safari parks, cryopreservation of gametes, in vitro fertilisation, tissue culture propagation, seed banks.
💡 Sacred groves are a unique Indian in situ conservation method. Ex situ includes modern techniques like cryopreservation and tissue culture—students often only list zoos and botanical gardens.
Exam Traps — Don't Make These Mistakes
⚠ Confusing genetic diversity with species diversity
✗ Genetic diversity refers to the number of different species in an area.
→ Genetic diversity is variation within a single species (e.g., different strains of rice), not between species. Species diversity is the variety of species in a community.
✓ Genetic diversity is the variation in genes and alleles within a species, such as the 50,000 genetically different strains of rice in India.
⚠ Misstating the Z value in species-area relationship
✗ The slope Z is always 0.1 to 0.2 for all areas.
→ Z = 0.1 to 0.2 applies to small areas within a region. For very large areas like entire continents, Z values are steeper (0.6 to 1.2).
✓ For small areas, Z lies in the range of 0.1 to 0.2; for very large areas like continents, Z ranges from 0.6 to 1.2.
⚠ Omitting the 'long evolutionary time' hypothesis for tropical diversity
✗ Tropics have more species because they receive more solar energy and have higher productivity.
→ This is only one of three hypotheses. Students often forget the other two: (a) tropical regions have remained relatively undisturbed for millions of years, providing long evolutionary time for species diversification, and (b) tropical environments are less seasonal, more constant and predictable, promoting niche specialisation.
✓ Three hypotheses explain tropical species richness: (1) long evolutionary time due to fewer glaciations, (2) constant and predictable environments promoting niche specialisation, and (3) more solar energy leading to higher productivity.
⚠ Confusing in situ and ex situ conservation
✗ In situ conservation means protecting species in zoos and botanical gardens.
→ In situ conservation protects species in their natural habitat (on site), e.g., national parks and biosphere reserves. Zoos and botanical gardens are ex situ (off site) conservation.
✓ In situ conservation protects species in their natural habitat, such as in national parks and wildlife sanctuaries. Ex situ conservation involves removing species from their habitat, e.g., in zoological parks and seed banks.
⚠ Forgetting that the 'Sixth Extinction' is different due to rate, not cause
✗ The current mass extinction is different because it is caused by humans, while previous ones were natural.
→ Previous mass extinctions were also natural, but the key difference is the rate: current extinction rates are 100 to 1,000 times faster than pre-human times, and human activities are responsible for this faster rate.
✓ The current 'Sixth Extinction' differs from previous mass extinctions in its rate—100 to 1,000 times faster than pre-human times—and is driven by human activities.
⚠ Misidentifying the number of biodiversity hotspots
✗ There are 25 biodiversity hotspots in the world.
→ Initially 25 were identified, but nine more were added, bringing the total to 34. The chapter explicitly states this update.
✓ There are 34 biodiversity hotspots in the world, of which three (Western Ghats and Sri Lanka, Indo-Burma, and Himalaya) cover India's biodiversity regions.
Compare & Contrast
Level of biological organisation
Genetic diversity
Species diversity
Genetic diversity refers to variation within a single species (e.g., different strains of rice), while species diversity refers to the variety of different species in a community (e.g., amphibian species in Western Ghats vs. Eastern Ghats).
Location of conservation
In situ conservation
Ex situ conservation
In situ conservation protects species in their natural habitat (e.g., national parks, biosphere reserves, sacred groves), while ex situ conservation involves removing species from their natural habitat for protection in artificial settings (e.g., zoological parks, botanical gardens, seed banks).
Type of benefit from biodiversity
Narrowly utilitarian argument
Broadly utilitarian argument
Narrowly utilitarian arguments focus on direct economic benefits like food, firewood, and medicines, while broadly utilitarian arguments focus on indirect ecosystem services like oxygen production, pollination, and aesthetic pleasures.
Exam Focus
Marks pattern: 1-2 MCQs (1 mark each) on definitions and examples, 1 Short Answer (2-3 marks) on patterns or causes of loss, 1 Long Answer (5 marks) on conservation methods or importance of biodiversity.
Most asked: Definition and levels of biodiversity (genetic, species, ecological) · Patterns of biodiversity: latitudinal gradient and species-area relationship · Causes of biodiversity loss: The Evil Quartet · Biodiversity conservation: in situ and ex situ methods, biodiversity hotspots · Importance of biodiversity: utilitarian and ethical arguments
Don't skip: Explain the three levels of biodiversity with examples.; Describe the patterns of biodiversity: latitudinal gradient and species-area relationship.; Discuss the four major causes of biodiversity loss (The Evil Quartet) with examples.; Differentiate between in situ and ex situ conservation with examples from India.
One-Line Revision (read aloud before the exam)
  1. Biodiversity is the combined diversity at all levels of biological organisation, popularised by Edward Wilson.
  2. Genetic diversity refers to variation within a species, e.g., 50,000 strains of rice in India.
  3. Species diversity is the variety of species in a community, e.g., Western Ghats have higher amphibian diversity than Eastern Ghats.
  4. Ecological diversity is the variety of ecosystems, e.g., India's deserts, rainforests, mangroves, and alpine meadows.
  5. India has 2.4% of world's land area but 8.1% of global species diversity, making it a mega diversity country.
  6. Species diversity decreases as we move from the equator towards the poles (latitudinal gradient).
  7. The species-area relationship on a log scale is log S = log C + Z log A, with Z = 0.1-0.2 for small areas and 0.6-1.2 for continents.
  8. The 'Evil Quartet' causes of biodiversity loss are habitat loss, over-exploitation, alien species invasions, and co-extinctions.
  9. Current extinction rates are 100-1,000 times faster than pre-human times, leading to the 'Sixth Extinction'.
  10. Biodiversity hotspots are 34 regions with high endemism and habitat loss; three are in India: Western Ghats-Sri Lanka, Indo-Burma, and Himalaya.
  11. In situ conservation protects species in natural habitats, e.g., national parks, biosphere reserves, and sacred groves.
  12. Ex situ conservation includes zoos, botanical gardens, cryopreservation, tissue culture, and seed banks.
  13. Sacred groves in Meghalaya, Rajasthan, and Western Ghats are traditional in situ conservation sites.
  14. The narrowly utilitarian argument for conservation includes direct economic benefits like food and medicine.
  15. The broadly utilitarian argument includes ecosystem services like oxygen production and pollination.
  16. The ethical argument states that every species has intrinsic value and we have a moral duty to protect them.
  17. The rivet popper hypothesis by Paul Ehrlich compares species to rivets in an airplane—losing species weakens the ecosystem.
  18. David Tilman's experiments showed that plots with more species had higher productivity and less year-to-year variation in biomass.
  19. The Convention on Biological Diversity (Earth Summit, 1992) called for conservation and sustainable use of biodiversity.
  20. More than 70% of all recorded species are animals, and among animals, insects make up more than 70%.

MCQs — 10 Questions with Answers

Q1. The term 'biodiversity' popularised by Edward Wilson refers to which of the following?

  • A. Diversity of species in an ecosystem only
  • B. Combined diversity at all levels of biological organisation including genetic, species, and ecological diversity ✓
  • C. Only the number of different animal species on Earth
  • D. Variation within plant populations alone

Answer: B — Biodiversity encompasses diversity at all biological levels — genetic (within species), species (between species), and ecological (between ecosystems).

Q2. India has 2.4% of the world's land area but accounts for what percentage of global species diversity?

  • A. 2.4%
  • B. 4.1%
  • C. 8.1% ✓
  • D. 12.5%

Answer: C — India's 8.1% global species diversity on only 2.4% land area makes it one of the 12 megadiverse countries in the world.

Q3. According to the latitudinal gradient pattern, which location should have the highest species diversity?

  • A. Greenland at 71° N
  • B. New York at 41° N
  • C. Colombia near the equator at 0° latitude ✓
  • D. Scandinavia at 55–70° N

Answer: C — The latitudinal gradient shows diversity decreases moving away from equator; Colombia has 1,400 bird species vs Greenland's 56, confirming equatorial maximum.

Q4. What percentage of all recorded animal species on Earth are insects?

  • A. More than 50%
  • B. Approximately 40%
  • C. More than 70% ✓
  • D. Less than 30%

Answer: C — Insects comprise more than 70% of all recorded animals, making them the most species-rich taxonomic group; 7 out of 10 animals are insects.

Q5. According to Robert May's estimates, approximately how many species exist on Earth in total?

  • A. 1.5 million species
  • B. 7 million species ✓
  • C. 20–50 million species
  • D. 3 million species

Answer: B — Robert May's conservative and scientifically sound estimate places global species diversity at about 7 million, compared to extreme estimates of 20–50 million.

Q6. Which of the following is NOT a type of biodiversity mentioned in the text?

  • A. Genetic diversity within rice populations
  • B. Species diversity of amphibians in Western Ghats
  • C. Ecological diversity of Indian ecosystems
  • D. Taxonomic diversity based on DNA sequencing ✓

Answer: D — The three main levels of biodiversity are genetic, species, and ecological; taxonomic diversity based on DNA sequencing is not mentioned as a separate category in the text.

Q7. A tropical rainforest of 100 hectares contains approximately how many times more vascular plant species than a temperate forest of equal area?

  • A. 2 times more
  • B. 5 times more
  • C. 10 times more ✓
  • D. 15 times more

Answer: C — The text states a tropical forest like Ecuador has up to 10 times as many species of vascular plants as a forest of equal area in a temperate region like the Midwest USA.

Q8. Why is it difficult to estimate the total number of prokaryotic species on Earth?

  • A. Prokaryotes are too small to see under light microscope
  • B. Conventional taxonomic methods are unsuitable, most species cannot be cultured in labs, and molecular criteria reveal millions of potential species ✓
  • C. All prokaryotes have identical genetic sequences
  • D. Prokaryotes do not have cell membranes

Answer: B — The text explains prokaryotic diversity is incalculable because conventional taxonomy fails for microbes, culturing is problematic, and biochemical/molecular criteria suggest millions of unculturable species exist.

Q9. If May's global estimate that 22% of total species have been recorded is applied to India's recorded 45,000 plant species, how many plant species are estimated to exist in India but remain undiscovered?

  • A. Approximately 45,000 species
  • B. Approximately 100,000 species
  • C. Approximately 160,000 species ✓
  • D. Approximately 200,000 species

Answer: C — If 45,000 plants = 22% of total, then total = 45,000 ÷ 0.22 ≈ 205,000; undiscovered = 205,000 − 45,000 ≈ 160,000 species (text estimates >100,000).

Q10. Both Statement 1 and Statement 2 are given below: Statement 1: The Amazonian rainforest contains more than 40,000 plant species and 3,000 fish species. Statement 2: The latitudinal gradient in biodiversity explains why temperate regions have higher species diversity than tropical regions. Which of the following is correct?

  • A. Statement 1 is true and Statement 2 is true
  • B. Statement 1 is true and Statement 2 is false ✓
  • C. Statement 1 is false and Statement 2 is true
  • D. Statement 1 is false and Statement 2 is false

Answer: B — Statement 1 is correct (Amazonian rainforest facts confirmed in text), but Statement 2 is false because the latitudinal gradient shows tropics have higher diversity than temperate regions, not the reverse.

Flashcards

What does biodiversity mean in biology?

Biodiversity is the combined diversity at all levels of biological organisation, including genetic, species, and ecological diversity.

Define genetic diversity with an example.

Genetic diversity is variation within a species population; India's 50,000 genetically different rice strains with varying traits is a classic example.

What is species diversity and where is it high in India?

Species diversity is the variety of different species in an area; the Western Ghats have greater amphibian species diversity than the Eastern Ghats.

How many species have been recorded globally according to IUCN 2004?

Slightly more than 1.5 million plant and animal species have been recorded, but millions more remain undiscovered.

What does the latitudinal gradient in biodiversity mean?

Species diversity decreases as you move away from the equator towards the poles; tropics have much higher diversity than temperate or polar regions.

Why is India considered a megadiverse country?

Although India has only 2.4% of world's land area, it contains 8.1% of global species diversity, making it one of 12 megadiverse nations.

How many bird species does Colombia have compared to Greenland?

Colombia (near equator) has nearly 1,400 bird species while Greenland (71° N) has only 56 species, illustrating the latitudinal gradient.

What percentage of recorded animal species on Earth are insects?

More than 70% of all recorded animals are insects, meaning 7 out of every 10 animals on Earth are insects.

What is the most conservative global estimate of total species on Earth?

Robert May's estimate places global species diversity at approximately 7 million species, more conservative than the extreme 20-50 million estimates.

Why is estimating prokaryotic species diversity difficult?

Conventional taxonomic methods don't work for microbes, most prokaryotes cannot be cultured in labs, and molecular criteria suggest millions of undiscovered species.

Important Board Questions

Define genetic diversity and give one example from India demonstrating this concept. [2 marks]

Genetic diversity = variation within a species across its range. Example: Rauwolfia vomitoria in Himalayas (reserpine potency differs) OR India's 50,000 genetically different rice strains OR 1,000 mango varieties.

Explain the latitudinal gradient pattern of biodiversity with suitable examples. Why does this pattern exist on Earth? [5 marks]

Define pattern: diversity decreases equator → poles. Examples: Colombia (equator) 1,400 birds vs New York (41°N) 105 vs Greenland (71°N) 56; tropical forests 10× plant species vs temperate forests. Reason: equatorial regions have stable climate, longer growing season, more energy, higher productivity supporting more species.

India is considered a megadiverse country despite having only 2.4% of the world's land area. Justify this statement with relevant data and explain what conservation challenges this megadiversity status poses. (6 marks — HOTS) [6 marks]

Justification: India has 8.1% global species diversity (>1% megadiverse threshold); 45,000 plants + 90,000 animals recorded; estimated 100,000+ plants + 300,000+ animals undiscovered (applying 22% discovery rate). Challenge: extinction rate faster than discovery rate — species going extinct before cataloguing; need for massive taxonomist manpower and funding; tropical megadiversity hotspots (Western Ghats, Northeast) under severe habitat loss pressure; less than 100 years to lose millions of species if current rates continue.

Assertion-Reason Questions for Biodiversity and Conservation

Q1. Assertion (A):

India, despite having only 2.4% of the world's land area, possesses 8.1% of global species diversity and is classified as a mega diversity country.

Reason (R):

India's high species diversity is due to its location in tropical latitudes, diverse topography, and varied ecosystems including rainforests, deserts, wetlands, and coral reefs.

Answer: A — Both A and R are true, and R is the correct explanation of A — Both the assertion and reason are true. India's megadiversity status is directly explained by its tropical location, geographic diversity, and multiple ecosystem types, which create conditions for high genetic, species, and ecological diversity.

Q2. Assertion (A):

The number of fungi species globally exceeds the combined total of fishes, amphibians, reptiles, and mammals.

Reason (R):

Fungi have a larger body size and require more specialized habitats than vertebrates, leading to greater species diversity.

Answer: C — A is true but R is false — The assertion is true, but the reason is false. Fungi are mostly microscopic and occupy diverse decomposer and parasitic roles with low dispersal barriers. Vertebrates actually require more specialized, macroscopic habitats. The reason incorrectly reverses the actual explanation.

Q3. Assertion (A):

Species diversity decreases as one moves away from the equator towards the poles (latitudinal gradient of biodiversity).

Reason (R):

Tropical regions near the equator receive higher solar radiation, leading to greater primary productivity and more available energy to support diverse food webs.

Answer: B — Both A and R are true, but R is NOT the correct explanation of A — Both the assertion and reason are true, but the reason is not the complete explanation for the latitudinal gradient. While energy availability is one factor, the reason doesn't fully address habitat complexity, speciation rates, and historical climate stability in tropics. The reason is partially explanatory but incomplete.

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Case-Based Questions (CBQ) for Biodiversity and Conservation

Case Study:

A research team surveyed amphibian species across four Indian regions: the Western Ghats (tropical, mountainous), the Eastern Ghats (tropical, less mountainous), the Deccan Plateau (semi-arid), and the Thar Desert (arid). They recorded 156 amphibian species in the Western Ghats, 89 in the Eastern Ghats, 34 on the Deccan Plateau, and only 8 in the Thar Desert. The team also noted that within the Western Ghats, different valleys separated by mountain ranges contained distinct populations of the same frog species with different mating call frequencies. They estimated that 40% of amphibians discovered in the Western Ghats had not yet been formally described in scientific literature.

Q1. The difference in amphibian species numbers between the Western Ghats (156 species) and Eastern Ghats (89 species) is an example of which type of biodiversity variation?

  • A. Genetic diversity within a species
  • B. Species diversity across geographic regions ✓
  • C. Ecological diversity of ecosystems
  • D. Population diversity within communities

Answer: B

Q2. The discovery that different Western Ghats valleys contain frog populations with different mating call frequencies in the same species demonstrates:

  • A. Species diversity, as different call frequencies indicate different species
  • B. Genetic diversity, showing allelic variation in behavior-controlling genes within the same species ✓
  • C. Ecological diversity, as mating calls reflect different ecosystem types
  • D. The impossibility of conservation due to population differences

Answer: B

Q3. Comparing amphibian richness across the four regions (Western Ghats > Eastern Ghats > Deccan Plateau > Thar Desert), which factor best explains this pattern?

  • A. The Western Ghats have larger land area than other regions
  • B. The Western Ghats receive the most rainfall due to monsoon patterns
  • C. Amphibians are only found in mountainous areas and absent from plateaus and deserts
  • D. The latitudinal gradient effect, where tropical and topographically complex regions near the equator support more species ✓

Answer: D

Q4. If 40% of Western Ghats amphibians remain undescribed and only 22% of global species have been recorded (Robert May's estimate), what does this suggest about India's actual amphibian diversity compared to recorded diversity?

  • A. India's recorded amphibian diversity is complete and no species remain to be discovered
  • B. All undiscovered species are less important than recorded species and need not be conserved
  • C. India likely has many undiscovered amphibian species, particularly in biodiversity hotspots like the Western Ghats; inventory is far from complete ✓
  • D. The Western Ghats should not be considered a conservation priority since species are constantly being discovered there

Answer: C

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Previous Year Questions (PYQ) for Biodiversity and Conservation

Real CBSE board exam questions from past papers — free to attempt.

CBSE 2026 · Set 57/1/1 · 1 mark

Select the mismatched pair:

  • Mega diversity countries in the world – 12
  • Genetically different strains of rice in India – Less than 1000
  • Robert Mays estimation on global species diversity – 7 million species worldwide
  • Zoological parks – Ex-situ conservation

CBSE 2026 · Set 57/1/1 · 1 mark

Which of the following sacred groves is found in Meghalaya?

  • Jaintia hills
  • Bastar
  • Chanda
  • Sarguja

CBSE 2026 · Set 57/1/1 · 2 marks

(b) In an ecosystem there was loss of biodiversity due to some project in that area. (i) How will biodiversity be affected? (2 points) (1 mark) (ii) List two major causes of loss of biodiversity. (1 mark)

CBSE 2026 · Set 57/1/2 · 1 mark

Exploration of molecular, genetic and species level diversity for gaining products of economic importance is called

  • Exploitation
  • Bio-prospecting
  • Bio-patenting
  • Bio-piracy

CBSE 2026 · Set 57/2/1 · 1 mark

Select the correct option :

  • Tropics between 23.5 ° N – 23.5° S –– Higher biodiversity than temperate areas
  • Columbia –– 105 bird species
  • New York –– 1400 bird species
  • India –– 2000 bird species

CBSE 2026 · Set 57/2/1 · 1 mark

What could be the reason of extinction of Abingdon Tortoise from Galapagos Islands ?

  • Intraspecific Competition
  • Predation
  • Parasitism
  • Interspecific Competition

CBSE 2026 · Set 57/2/1 · 1 mark

Assertion (A) : IUCN Red List helps in identifying and protecting endangered species worldwide. Reason (R) : The list includes the species facing risk of extinction.

  • Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation for Assertion (A).
  • Both Assertion (A) and Reason (R) are true, but Reason (R) is not correct explanation for Assertion (A).
  • Assertion (A) is true, Reason (R) is false.
  • Assertion (A) is false, Reason (R) is true.

CBSE 2026 · Set 57/2/1 · 2 marks

(b) What factors contribute to the Amazonian rain forests in South America being the most biodiverse regions on Earth ?

CBSE 2026 · Set 57/2/2 · 1 mark

If A = species richness and B = Endemism then biodiversity hotspots have

  • low degree of A and low degree of B.
  • low degree of A and high degree of B.
  • high degree of A and low degree of B.
  • high degree of A and high degree of B.

CBSE 2026 · Set 57/2/2 · 2 marks

What factors contribute to the Amazonian rain forests in South America being the most biodiverse regions on Earth?

CBSE 2026 · Set 57/2/3 · 1 mark

Current percentage of tropical rainforests covering the Earth's land surface is

  • 14%
  • 6%
  • 8%
  • 15%

CBSE 2026 · Set 57/2/3 · 1 mark

What could be the reason of extinction of Abingdon Tortoise from Galapagos Islands?

  • Intraspecific Competition
  • Predation
  • Parasitism
  • Interspecific Competition

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