Important Questions Class 12 Biology Chapter 13 Biodiversity and Conservation With Answers

Biodiversity is the total variety of life present at genetic, species, and ecosystem levels.
Rice varieties, amphibians in the Western Ghats, coral reefs, mangroves, and sacred groves show biodiversity.

Biodiversity becomes a high-scoring chapter when students connect facts, examples, conservation logic, and India-specific data. Important Questions Class 12 Biology Chapter 13 help students revise Biodiversity and Conservation for CBSE 2026-27 board exams, school tests, and pre-board papers. NCERT Chapter 13 covers biodiversity levels, India’s species richness, latitudinal gradients, species-area relationship, ecosystem stability, biodiversity loss, the Evil Quartet, in situ conservation, ex situ conservation, hotspots, sacred groves, and global conservation efforts.

Key Takeaways

• Biodiversity: Biodiversity includes genetic diversity, species diversity, and ecological diversity.
• India’s Richness: India has only 2.4 percent of the world’s land area but 8.1 percent of global species diversity.
• Species Loss: Habitat loss, over-exploitation, alien species invasion, and co-extinction form the Evil Quartet.
• Conservation: In situ conservation protects species in natural habitats, while ex situ conservation protects them outside habitats.

Important Questions Class 12 Biology Chapter 13 Structure 2026-27

Important Questions Class 12 Biology Chapter 13 for CBSE 2026-27

Biodiversity questions in CBSE Biology often combine definitions with exact NCERT examples. Students should remember India-specific figures, named scientists, conservation sites, and causes of species extinction.

1. What is biodiversity?

Biodiversity is the combined diversity at all levels of biological organisation. It includes variation from genes to species and ecosystems.

1. Genetic diversity occurs within a species.
2. Species diversity occurs among species.
3. Ecological diversity occurs among ecosystems.

Example:
India shows forests, deserts, mangroves, wetlands, coral reefs, and alpine meadows.

2. Who popularised the term biodiversity?

Edward Wilson popularised the term biodiversity. He used it to describe the combined diversity at all biological levels.

1. Biodiversity includes variation inside cells.
2. It also includes species-level diversity.
3. It extends up to biome-level diversity.

Final answer:
Edward Wilson popularised the term biodiversity.

3. Name the three important levels of biodiversity.

The three important levels of biodiversity are genetic diversity, species diversity, and ecological diversity.

1. Genetic diversity: variation within a species.
2. Species diversity: variation among species.
3. Ecological diversity: variation among ecosystems.

Final answer:
Genetic diversity, species diversity, and ecological diversity

Biodiversity and Conservation Class 12 Important Questions on Types of Biodiversity

The three levels of biodiversity help students understand conservation beyond counting species. CBSE 2026-27 questions can ask examples from India, Western Ghats, rice varieties, mango varieties, and ecosystem types.

4. What is genetic diversity Class 12 Biology?

Genetic diversity is the variation in genes within a single species over its distributional range. It allows populations to adapt to local conditions.

Examples:

1. Rauwolfia vomitoria shows genetic variation in reserpine potency.
2. India has more than 50,000 genetically different rice strains.
3. India has about 1,000 mango varieties.

Final fact:
Genetic diversity supports adaptation and survival.

5. What is species diversity Class 12 Biology?

Species diversity is the variety of species present in a region. It compares richness across different regions or ecosystems.

Example:
The Western Ghats have greater amphibian species diversity than the Eastern Ghats.

1. Species diversity counts different species.
2. It also reflects the richness of a region.
3. Tropical regions usually show higher species diversity.

Final fact:
Species diversity is a major measure of biodiversity.

6. What is ecological diversity Class 12 Biology?

Ecological diversity is the variety of ecosystems present in a region. It includes different habitats and ecological communities.

Indian examples:

1. Deserts
2. Rain forests
3. Mangroves
4. Coral reefs
5. Wetlands
6. Estuaries
7. Alpine meadows

Final fact:
India has greater ecological diversity than many countries with fewer ecosystem types.

Class 12 Biology Chapter 13 Important Questions on Global and Indian Biodiversity

NCERT gives several exact figures from global and Indian biodiversity. These facts help in 1-mark questions, assertion-reason questions, and short-answer board questions.

7. How many species have been described on Earth?

Slightly more than 1.5 million plant and animal species had been described according to IUCN 2004. Many species remain undiscovered.

1. Published records include discovered and named species.
2. Several species remain unknown, especially in tropical regions.
3. Robert May estimated global species diversity at about 7 million.

Final fact:
Known species represent only part of Earth’s biodiversity.

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

It is difficult because many species remain undiscovered, especially in tropical regions and microbial groups. Conventional taxonomy cannot identify all microbes.

1. Species inventories are better in temperate regions.
2. Tropical regions contain many undiscovered species.
3. Many prokaryotes cannot grow in laboratory culture.
4. Molecular criteria may reveal millions of microbial forms.

Final fact:
Global species estimates remain uncertain.

9. What percentage of recorded species are animals and plants?

More than 70 percent of recorded species are animals, while plants form no more than 22 percent. Insects dominate animal diversity.

1. Animals form the largest recorded group.
2. Plants include algae, fungi, bryophytes, gymnosperms, and angiosperms.
3. Insects form more than 70 percent of animal species.

Final fact:
Out of every 10 animal species, about 7 are insects.

10. Why is India called a mega diversity country?

India is called a mega diversity country because it has 8.1 percent of global species diversity despite only 2.4 percent of the world’s land area.

1. India has nearly 45,000 recorded plant species.
2. India has about twice as many recorded animal species.
3. India contains tropical forests, deserts, wetlands, mangroves, and coral reefs.

Final fact:
India is one of the 12 mega diversity countries listed in NCERT.

Biodiversity Class 12 Questions With Answers on Patterns of Biodiversity

Biodiversity does not show equal distribution across Earth. Two major NCERT patterns are latitudinal gradients and species-area relationship.

11. What is latitudinal gradient in biodiversity?

Latitudinal gradient means species diversity decreases from the equator towards the poles. Tropical regions have more species than temperate and polar regions.

Examples:

1. Colombia has nearly 1,400 bird species.
2. New York has about 105 bird species.
3. Greenland has only about 56 bird species.
4. India has more than 1,200 bird species.

Final fact:
The tropics between 23.5° N and 23.5° S show high biodiversity.

12. Why do tropical regions have greater biodiversity?

Tropical regions have greater biodiversity due to long evolutionary time, stable climate, and high solar energy. These conditions support speciation and productivity.

Reasons:

1. Tropical regions remained less disturbed for millions of years.
2. Their climate is less seasonal and more predictable.
3. More solar energy increases productivity.

Final fact:
High productivity can support greater species richness.

13. Why does the Amazon rainforest have very high biodiversity?

The Amazon rainforest has very high biodiversity because it lies in the tropics and has high productivity. It supports thousands of plant and animal species.

NCERT examples:

1. More than 40,000 plant species.
2. About 3,000 fish species.
3. About 1,300 bird species.
4. About 427 mammal species.
5. More than 1,25,000 invertebrate species.

Final fact:
Amazonian rain forest has the greatest biodiversity on Earth.

Species Area Relationship Class 12 Biology Questions

Species richness usually increases when explored area increases, but only up to a limit. NCERT explains this pattern through Alexander von Humboldt’s observations.

14. What is species-area relationship?

Species-area relationship explains that species richness increases with explored area up to a limit. The relationship usually forms a rectangular hyperbola.

1. Alexander von Humboldt observed this pattern.
2. It applies to plants, birds, bats, and freshwater fishes.
3. On a logarithmic scale, the relationship becomes a straight line.

Final fact:
Species richness depends on area explored.

15. Write the equation for species-area relationship.

The species-area relationship is represented by log S = log C + Z log A. This equation forms a straight line on a logarithmic scale.

Formula:
log S = log C + Z log A

Where:

1. S = species richness
2. A = area
3. Z = slope of the line
4. C = Y-intercept

Final answer:
log S = log C + Z log A

16. What is the significance of Z in species-area relationship?

Z represents the slope of the regression line in the species-area relationship. It shows how species richness changes with area.

1. For small or normal areas, Z usually ranges from 0.1 to 0.2.
2. For very large areas, Z ranges from 0.6 to 1.2.
3. For fruit-eating birds and mammals in tropical forests, Z is about 1.15.

Final fact:
Steeper slopes show a faster rise in species richness with area.

Species Diversity Class 12 Biology Questions on Ecosystem Stability

Species diversity supports ecosystem productivity, resistance, and resilience. NCERT uses David Tilman’s experiments and Paul Ehrlich’s rivet popper hypothesis to explain this idea.

17. How does species diversity affect ecosystem stability?

Higher species diversity generally makes communities more stable. Stable communities show less variation in productivity and better resistance to disturbances.

1. They resist occasional natural or human disturbances.
2. They show resilience after disturbance.
3. They resist invasion by alien species.
4. They maintain more stable productivity.

Final fact:
Species-rich communities often function more reliably.

18. What did David Tilman’s experiments show?

David Tilman’s long-term experiments showed that plots with more species had less year-to-year variation in biomass. Increased diversity also supported higher productivity.

1. Species-rich plots showed more stable biomass.
2. Diversity reduced productivity fluctuation.
3. Increased diversity contributed to higher productivity.

Final answer:
Tilman’s experiments supported the link between diversity and ecosystem stability.

19. What is the rivet popper hypothesis?

The rivet popper hypothesis compares species loss to removing rivets from an aeroplane. It was proposed by Paul Ehrlich.

1. An ecosystem is compared to an aeroplane.
2. Species are compared to rivets.
3. Removing a few rivets may not cause immediate failure.
4. Continued loss can weaken the whole system.

Final fact:
Loss of key species can damage ecosystem functioning more seriously.

Loss of Biodiversity Class 12 Important Questions

Human activities have increased extinction rates far beyond natural background levels. CBSE 2026-27 questions can ask recent extinctions, threatened groups, and the effects of biodiversity loss.

20. What is biodiversity loss?

Biodiversity loss is the decline or extinction of species, genes, or ecosystems from a region. Human activities are the major cause of current biodiversity loss.

1. Species extinction reduces biological wealth.
2. Habitat destruction removes natural homes.
3. Pollution and overuse further increase the loss.

Final fact:
Current extinction rates are 100 to 1,000 times faster than pre-human times.

21. Name some recently extinct animals mentioned in NCERT.

NCERT mentions dodo, quagga, thylacine, Steller’s sea cow, and three tiger subspecies as recent extinctions.

Examples:

1. Dodo from Mauritius.
2. Quagga from Africa.
3. Thylacine from Australia.
4. Steller’s sea cow from Russia.
5. Bali, Javan, and Caspian tiger subspecies.

Final fact:
Many recent extinctions link directly to human activities.

22. What are the effects of biodiversity loss?

Biodiversity loss can reduce plant production, lower resistance to disturbances, and increase ecosystem variability.

Effects:

1. Decline in plant production.
2. Lower resistance to drought and other disturbances.
3. Increased variability in productivity.
4. Disturbed water use.
5. Changes in pest and disease cycles.

Final fact:
Biodiversity loss weakens ecosystem functioning.

Evil Quartet Class 12 Biology Questions on Causes of Biodiversity Loss

NCERT calls the four major causes of biodiversity loss the Evil Quartet. These causes appear often in CBSE short-answer and long-answer questions.

23. What is the Evil Quartet in biodiversity?

The Evil Quartet refers to four major causes of biodiversity loss. These are habitat loss, over-exploitation, alien species invasion, and co-extinction.

The four causes are:

1. Habitat loss and fragmentation.
2. Over-exploitation.
3. Alien species invasions.
4. Co-extinctions.

Final answer:
The Evil Quartet explains the main human-driven causes of species loss.

24. Why is habitat loss and fragmentation the most important cause of extinction?

Habitat loss and fragmentation destroy or break natural habitats into smaller parts. This harms species that need large territories or migration routes.

1. Tropical rain forests show major habitat loss.
2. Large habitats become small fragments.
3. Mammals and birds needing large areas suffer.
4. Migratory animals face population decline.

Final fact:
Habitat loss is the most important cause of biodiversity loss.

25. How does over-exploitation cause species extinction?

Over-exploitation causes extinction when humans harvest species faster than they can recover. It happens when need turns into greed.

Examples:

1. Steller’s sea cow became extinct due to over-exploitation.
2. Passenger pigeon also became extinct due to overuse.
3. Many marine fish populations face over-harvesting.

Final fact:
Commercial overuse can threaten species survival.

26. How do alien species invasions cause biodiversity loss?

Alien species invasions cause biodiversity loss when introduced species become invasive and harm native species.

Examples:

1. Nile perch caused extinction of over 200 cichlid fish species in Lake Victoria.
2. Parthenium threatens native species.
3. Lantana threatens native vegetation.
4. Water hyacinth damages aquatic ecosystems.
5. African catfish threatens indigenous catfishes in Indian rivers.

Final fact:
Invasive alien species can replace or destroy native biodiversity.

27. What is co-extinction?

Co-extinction occurs when the extinction of one species causes the extinction of another dependent species. It happens in close biological associations.

Examples:

1. A host fish extinction can eliminate its specific parasites.
2. A plant extinction can eliminate its dependent pollinator.
3. A pollinator extinction can eliminate its coevolved plant partner.

Final fact:
Co-extinction links one species’ survival to another.

Biodiversity Conservation Class 12 NCERT Questions

Biodiversity conservation protects ecosystem services, useful resources, and the moral value of life. NCERT groups reasons for conservation into narrowly utilitarian, broadly utilitarian, and ethical arguments.

28. Why should we conserve biodiversity?

We should conserve biodiversity for direct benefits, ecosystem services, and ethical reasons. Biodiversity supports human survival and ecosystem health.

Reasons:

1. It provides food, fibre, firewood, medicines, and industrial products.
2. It supports pollination, oxygen production, climate control, and flood control.
3. It has intrinsic value beyond human use.

Final fact:
Conserving biodiversity protects present and future generations.

29. What are narrowly utilitarian reasons for conserving biodiversity?

Narrowly utilitarian reasons focus on direct economic benefits from biodiversity. These benefits come from food, medicines, materials, and industrial products.

Examples:

1. Cereals and pulses.
2. Fruits and fibres.
3. Firewood and construction material.
4. Tannins, dyes, resins, and perfumes.
5. Medicinal plants.

Final fact:
More than 25 percent of drugs sold worldwide come from plants.

30. What are broadly utilitarian reasons for conserving biodiversity?

Broadly utilitarian reasons focus on ecosystem services provided by biodiversity. These services support life and environmental balance.

Examples:

1. Oxygen production through photosynthesis.
2. Pollination by bees, birds, bats, and bumblebees.
3. Climate moderation.
4. Flood control.
5. Soil erosion control.

Final fact:
Amazon forests contribute about 20 percent of total atmospheric oxygen through photosynthesis.

31. What is the ethical reason for conserving biodiversity?

The ethical reason says every species has intrinsic value, even if it has no current economic use. Humans share Earth with millions of species.

1. Every species has a right to exist.
2. Humans have a moral duty towards other life forms.
3. Future generations should inherit biological wealth.

Final fact:
Ethical conservation values life beyond human profit.

Biodiversity Hotspots in India Class 12 Questions

Hotspots are regions with high species richness, high endemism, and rapid habitat loss. India has biodiversity-rich regions that fall under global hotspot areas.

32. What are biodiversity hotspots?

Biodiversity hotspots are regions with very high species richness and high endemism. They also face serious habitat loss.

1. Endemism means species occur only in that region.
2. Hotspots contain many threatened species.
3. Their protection can reduce extinction risk.

Final fact:
NCERT mentions 34 biodiversity hotspots in the world.

33. Name the biodiversity hotspots that cover India.

The biodiversity hotspots that cover India are Western Ghats and Sri Lanka, Indo-Burma, and Himalaya. These regions contain exceptional biodiversity.

1. Western Ghats and Sri Lanka.
2. Indo-Burma.
3. Himalaya.

Final fact:
These hotspots include India’s rich biodiversity regions.

34. Why are biodiversity hotspots important for conservation?

Biodiversity hotspots are important because they protect many endemic and threatened species in limited land area.

1. They cover less than 2 percent of Earth’s land area.
2. They collectively contain very high species richness.
3. Strict protection can reduce ongoing mass extinctions by about 30 percent.

Final fact:
Hotspots give high conservation value for limited resources.

In Situ Conservation Class 12 Questions

In situ conservation protects species inside their natural habitat. This approach protects the whole ecosystem instead of only one species.

35. What is in situ conservation?

In situ conservation is the protection of species in their natural habitat. It conserves the whole ecosystem along with its biodiversity.

Examples:

1. Biosphere reserves.
2. National parks.
3. Wildlife sanctuaries.
4. Sacred groves.

Final fact:
Saving an entire forest helps save the tiger and many associated species.

36. What are sacred groves?

Sacred groves are forest patches protected through religious and cultural traditions. Trees and wildlife in them receive total protection.

Indian examples:

1. Khasi and Jaintia Hills in Meghalaya.
2. Aravalli Hills of Rajasthan.
3. Western Ghats of Karnataka and Maharashtra.
4. Sarguja, Chanda, and Bastar areas of Madhya Pradesh.

Final fact:
Sacred groves in Meghalaya protect many rare and threatened plants.

37. Name India’s protected areas mentioned in NCERT.

NCERT mentions biosphere reserves, national parks, wildlife sanctuaries, and sacred groves as protected areas in India.

Figures given in NCERT:

1. 14 biosphere reserves.
2. 90 national parks.
3. 448 wildlife sanctuaries.

Final fact:
These protected areas support in situ conservation.

Ex Situ Conservation Class 12 Questions

Ex situ conservation protects threatened species outside their natural habitat. It helps species that need urgent protection from extinction.

38. What is ex situ conservation?

Ex situ conservation is the protection of threatened species outside their natural habitat. It places them in special settings with care.

Examples:

1. Zoological parks.
2. Botanical gardens.
3. Wildlife safari parks.
4. Seed banks.
5. Cryopreservation facilities.

Final fact:
Ex situ conservation helps species at high risk in the wild.

39. What are the methods of ex situ conservation?

The methods of ex situ conservation include zoological parks, botanical gardens, cryopreservation, in vitro fertilisation, tissue culture, and seed banks.

Methods:

1. Threatened animals kept in zoological parks.
2. Threatened plants grown in botanical gardens.
3. Gametes stored by cryopreservation.
4. Eggs fertilised in vitro.
5. Plants propagated by tissue culture.
6. Seeds stored in seed banks.

Final fact:
Ex situ methods protect species outside natural habitats.

40. Distinguish between in situ and ex situ conservation.

In situ conservation protects species in natural habitats, while ex situ conservation protects them outside natural habitats.

Final fact:
Both methods support biodiversity conservation.

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