NCERT Class 12 Biology Biology: Chapter 13 — BIODIVERSITY AND CONSERVATION
This chapter, 'Biodiversity and Conservation,' introduces the vast diversity of life on Earth, a concept popularized by Edward Wilson. It explains biodiversity at three levels: genetic diversity (variations within a species, like Rauwolfia vomitoria's reserpine content or India's rice and mango strains), species diversity (differences between species, e.g., amphibian diversity in the Western Ghats vs. Eastern Ghats), and ecological diversity (variety of ecosystems, such as India's deserts, rainforests, and mangroves). The chapter highlights that this rich biodiversity, accumulated over millions of years, is rapidly declining. It poses critical questions about the reasons for species diversity, its evolutionary history, and its importance to the biosphere and human well-being. The text also discusses the challenge of estimating the total number of species on Earth, with current estimates ranging from 1.5 million described species to a potential 7 million or more, emphasizing the ongoing discovery of new species, particularly in tropical regions. Understanding and conserving this biodiversity is presented as a vital environmental issue for our planet's survival.
Quick info
| Board | CBSE / NCERT |
|---|---|
| Class | Class 12 |
| Subject | Biology |
| Book | Biology |
| Chapter | Chapter 13 — BIODIVERSITY AND CONSERVATION |
| Language | English |
| PDF type | NCERT Textbook |
| Session | CBSE 2026 |
| Reading time | 4 minutes |
| Word count | 642 |
Learning outcomes
- Define and differentiate between genetic, species, and ecological diversity.
- Understand the scale of biodiversity on Earth and the challenges in estimating species numbers.
- Recognize the rapid loss of biodiversity and its implications.
- Appreciate the importance of biodiversity for the biosphere and human well-being.
Vocabulary
| Word | Meaning |
|---|---|
| Biodiversity | The variety of life in the world or in a particular habitat or ecosystem. |
| Genetic diversity | The total number of genetic characteristics in the genetic makeup of a species. |
| Species diversity | The number of different species that are represented in a given community. |
| Ecological diversity | The variety of habitats, communities, and ecological processes in the biosphere. |
| Biosphere | The regions of the surface, atmosphere, and hydrosphere of the earth occupied by living organisms. |
| Macromolecules | Large complex molecules, such as proteins and nucleic acids, essential for life. |
| Biomes | A large naturally occurring community of flora and fauna occupying a major habitat, e.g., forest or tundra. |
| Taxonomic groups | Categories used in the classification of organisms based on shared characteristics. |
| Species richness | The number of different species present in a particular area. |
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Practice questions
- What is biodiversity? Answer: Biodiversity is the term used to describe the combined diversity at all levels of biological organisation.
- Name the three levels of biodiversity. Answer: The three levels of biodiversity are genetic diversity, species diversity, and ecological diversity.
- Give an example of genetic diversity. Answer: Genetic diversity can be seen in the different strains of rice or varieties of mango found in India, or in the varying potency of reserpine in different Himalayan ranges of Rauwolfia vomitoria.
- How does ecological diversity differ between India and Norway? Answer: India has greater ecological diversity with its deserts, rainforests, mangroves, etc., compared to a Scandinavian country like Norway.
- What is the estimated global species diversity according to Robert May? Answer: Robert May's conservative estimate places the global species diversity at about 7 million.
Practice MCQs
Q1. Who popularized the term 'biodiversity'?
Explanation: Edward Wilson, a sociobiologist, is credited with popularizing the term biodiversity.
Q2. Which of the following is NOT a level of biodiversity?
Explanation: The chapter explicitly mentions genetic, species, and ecological diversity as the main levels.
Q3. The diversity in the medicinal plant Rauwolfia vomitoria's reserpine content is an example of:
Explanation: Variations within a single species, like the potency of a chemical, represent genetic diversity.
Q4. Which region has greater amphibian species diversity according to the text?
Explanation: The text states that the Western Ghats have greater amphibian species diversity than the Eastern Ghats.
Q5. According to IUCN (2004), approximately how many species have been described so far?
Explanation: The International Union for Conservation of Nature and Natural Resources (IUCN) reported slightly more than 1.5 million described species in 2004.
Q6. Which country is mentioned as having greater ecosystem diversity than Norway?
Explanation: India, with its diverse habitats like deserts, rainforests, and mangroves, is cited as an example of high ecological diversity compared to Norway.
Frequently asked questions
What is biodiversity?
Biodiversity refers to the variety of life on Earth at all its levels, from genes to ecosystems, and the ecological and evolutionary processes that sustain it.
What are the three main levels of biodiversity?
The three main levels are genetic diversity (variation within species), species diversity (variety of species), and ecological diversity (variety of ecosystems).
How many species are estimated to exist on Earth?
While about 1.5 million species have been described, estimates for the total number of species on Earth vary widely, with a scientifically sound estimate by Robert May suggesting around 7 million.
Why is biodiversity important?
Biodiversity is crucial for the stability and functioning of the biosphere and provides numerous benefits for human survival and well-being.
Are species being lost rapidly?
Yes, the chapter indicates that the current rates of species loss could lead to the loss of accumulated biodiversity in less than two centuries.
Where are most undiscovered species likely to be found?
A large proportion of species yet to be discovered and described are expected to be found in tropical countries.
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NCERT Class 12 Biology — Biology — Chapter 13 — BIODIVERSITY AND CONSERVATION. Verified by NCERT Help Editorial Team. Reviewed on 29 Jul 2026. Last updated 10 Aug 2026.