Chapter 14: Life On The Earth
Source: NCERT Official Textbook
The chapter breaks down biodiversity into three hierarchical levels: Genetic Diversity (variation of genes within a species), Species Diversity (the variety of species in an area), and Ecosystem Diversity (the diversity of habitats and ecological processes).
It elaborates on the critical roles biodiversity plays: an Ecological Role (maintaining ecosystem functions like nutrient cycling and climate regulation), an Economic Role (as a reservoir of resources for food, medicine, and materials), and a Scientific Role (providing clues about evolution and life’s functioning).
The second half addresses the alarming Loss of Biodiversity, citing causes like human overpopulation, overexploitation, deforestation, natural calamities, pollution, and the introduction of exotic species. The IUCN’s classification of threatened species into Endangered, Vulnerable, and Rare categories is explained.
The chapter concludes with the Conservation of Biodiversity, stressing the need for sustainable development, community involvement, and international cooperation, referencing the Earth Summit (1992) and the Convention on Biodiversity.
It introduces the concepts of mega-diversity countries and biodiversity hotspots—areas with high species richness facing severe threats—and highlights legal frameworks like India’s Wild Life (Protection) Act, 1972, for establishing protected areas.
Topics Covered:
Section A: Descriptive Questions
- What is biodiversity? Explain it in simple terms. (Pg. 2) Page 115
- Name and briefly explain the three levels at which biodiversity can be discussed. (Pg. 2-3) Page 115-116
- What is Species Diversity and how can it be measured? (Pg. 3) Page 116
- List the three main roles (ecological, economic, and scientific) played by biodiversity. (Pg. 3-4) Page 116-117
- Why is the scientific role of biodiversity important? (Pg. 4) Page 117
- What are the major causes for the loss of biodiversity as mentioned in the chapter? (Pg. 4) Page 117
- What are the steps suggested by the world conservation strategy for biodiversity conservation? (List key points). (Pg. 5) Page 118
- What are biodiversity hotspots? How are they defined? (Pg. 5) Page 118
Section B1: Objective MCQs
Biodiversity is consistently richer in which regions? (Pg. 2)
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Reference: NCERT Page 115
What does Genetic Diversity refer to? (Pg. 2)
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Reference: NCERT Page 115
Areas rich in species diversity are called: (Pg. 3)
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Reference: NCERT Page 116
Which role of biodiversity includes the concept of ‘crop diversity’ or agro-biodiversity? (Pg. 3)
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Reference: NCERT Page 116
According to the chapter, what is our ethical responsibility towards other species? (Pg. 4)
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Reference: NCERT Page 117
Species which are not natural inhabitants but are introduced into a local habitat are called: (Pg. 4)
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Reference: NCERT Page 117
The Convention on Biodiversity was signed at the Earth Summit in 1992 in: (Pg. 5)
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Reference: NCERT Page 118
(Exercise) Conservation of biodiversity is important for: (Pg. 6)
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Reference: NCERT Page 119
(Exercise) Threatened species are those which: (Pg. 6)
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Reference: NCERT Page 119
(Exercise) National parks and sanctuaries are established for the purpose of: (Pg. 6)
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Reference: NCERT Page 119
(Exercise) Biodiversity is richer in: (Pg. 7)
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Reference: NCERT Page 120
(Exercise) In which country was the ‘Earth Summit’ held? (Pg. 7)
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Reference: NCERT Page 120
Section B2: Factual One-Liners
Biodiversity is a combination of two words: Bio (life) and ______ (variety). (Pg. 2) Page 115
Reveal Answer
Groups of individual organisms having certain similarities in their physical characteristics are called ______. (Pg. 2) Page 115
Reveal Answer
The broad differences between ecosystem types and the diversity of habitats constitute ______ diversity. (Pg. 3) Page 116
Reveal Answer
Species capture and store energy, produce and decompose organic materials, and help cycle water and nutrients, fulfilling the ______ role of biodiversity. (Pg. 3) Page 116
Reveal Answer
The International Union for Conservation of Nature publishes the ______ List of threatened species. (Pg. 4) Page 117
Reveal Answer
The IUCN classifies threatened species into three categories: Endangered, Vulnerable, and ______ Species. (Pg. 4) Page 117
Reveal Answer
Countries situated in tropical regions that possess a large number of the world’s species are called ______ centres. (Pg. 5) Page 118
Reveal Answer
(Exercise) The different levels of biodiversity are genetic, species, and ______. (Pg. 7) Page 120