# Biodiversity and Conservation, Class 12 Biology | SwaVid

Biodiversity and Conservation, NCERT Class 12 Biology: notes with key ideas, key terms, common mistakes and 3 quick checks with worked answers.

Canonical: https://www.swavid.com/cbse/class-12/biology/chapter/biodiversity-and-conservation

Source: https://www.swavid.com/cbse/class-12/biology/chapter/biodiversity-and-conservation

# Biodiversity and Conservation

## Key terms

## Key ideas

## Common mistakes

## Quick checks

## Keep going

## Questions parents ask

## Class 12 Biology on SwaVid

### Levels of biodiversity

### Global and Indian species richness

### Patterns of biodiversity

### Importance of species diversity

### Loss of biodiversity

### Biodiversity conservation

### Related chapter

### Related chapter

### All chapters

SwaVid › CBSE › Class 12 › Biology › Biodiversity and Conservation

Notes written by SwaVid from the NCERT textbook.

Class 12 Biology, Chapter 13. Key ideas, formulas and common mistakes.

CBSE prints 10 marks for Unit X, not for this chapter alone.

Short answer. This chapter explains the levels and patterns of biodiversity, the reasons for its rapid loss, and the methods used to conserve it. It shows that maintaining global species richness is necessary for ecological stability and human survival.

Source: NCERT Biology (Reprint 2026-27) , Chapter 13, Biodiversity and Conservation

Edward Wilson popularised the term biodiversity to describe combined diversity at all levels of biological organisation. It includes genetic diversity within a species, species diversity at the community level, and ecological diversity across distinct ecosystems.

According to Robert May, global species diversity is roughly 7 million, of which only about 1.5 million have been recorded. India contains 2.4 percent of the world's land area but contributes 8.1 percent of global species diversity, making it one of the 12 mega diversity nations.

Species diversity decreases from the equator towards the poles due to historical climate stability, higher solar energy, and less seasonal variation in the tropics. Alexander von Humboldt observed that within a region, species richness increases with explored area up to a limit.

David Tilman demonstrated through outdoor plots that communities with more species show less year-to-year variation in total biomass and higher productivity. Paul Ehrlich proposed the rivet popper hypothesis to show how ecosystem health collapses when key species are removed.

The accelerated rate of species extinction is driven by human activities, summarised as the Evil Quartet: habitat loss and fragmentation, over-exploitation, alien species invasions, and co-extinctions.

Conservation approaches are classified into in situ (on-site) and ex situ (off-site) methods. In situ methods protect endangered species in their natural habitats like biosphere reserves, national parks, and sacred groves, while ex situ methods include zoological parks, botanical gardens, and seed banks.

Try each question first. Then tap it to see the answer.

Plotting species richness (S) against area (A) produces a rectangular hyperbola: S = C A^Z.

Taking logarithms on both sides transforms the equation to log S = log C + Z log A.

This logarithmic equation is linear.

Rectangular hyperbola on a normal scale, and a straight line on a logarithmic scale

The standard range of Z across small regions is 0.1 to 0.2.

For very large areas like entire continents, the slope is much steeper, between 0.6 and 1.2.

For frugivorous birds and mammals in tropical forests of different continents, NCERT records Z as 1.15.

1.15

Sacred groves protect trees and wildlife in their native tract, so they are in situ.

Seed banks keep gametes or seeds preserved outside their natural habitats, so they are ex situ.

Biosphere reserves protect entire native ecosystems on-site, so they are in situ.

Sacred grove: in situ; Seed bank: ex situ; Biosphere reserve: in situ

Ecosystem .

Organisms and Populations .

The 13 chapters of Class 12 Biology .

CBSE does not give marks to one chapter. It prints 10 marks for Unit X, Ecology and Environment, which includes Biodiversity and Conservation.

No. They are written by SwaVid from the NCERT textbook. The CBSE curriculum is the reference for what is assessed.

This is the last chapter in the NCERT books for Class 12 Biology.

SwaVid is an AI tutor for Indian students in Classes 6 to 12. It finds the earlier ideas a child missed, then teaches today’s chapter. Start free to see how it works.

- Ch 13 NCERT book
- 10 marks, Unit X
- 3 quick checks
- Confusing in situ conservation sites with ex situ conservation sites . Remember that national parks, wildlife sanctuaries, biosphere reserves, and sacred groves are in situ, while botanical gardens, zoos, and seed banks are ex situ.
- Assuming that a steeper slope of Z means lower species richness . A steeper slope (larger Z value, such as 0.6 to 1.2) means species richness increases more rapidly as area expands, typically observed over whole continents.
- Treating Robert May's global estimate as the total number of already described species . Robert May estimated that about 7 million species exist on Earth in total, while the IUCN recorded that slightly more than 1.5 million species have actually been described so far.

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