What traumatic event does Zitkala-Sa describe at the school?

The forcible cutting of her long hair

Why was the cutting of her hair so humiliating to Zitkala-Sa?

Among her people, shingled hair was worn by cowards and mourners

Name the three levels of biodiversity.

Genetic diversity, species diversity and ecological (ecosystem) diversity.

What is the latitudinal gradient in diversity?

Species diversity generally decreases from the equator toward the poles; tropical regions have greater biodiversity than temperate or polar regions.

Write the species-area relationship equation.

The relationship is \\( \\log S = \\log C + Z \\log A \\), where S is species richness, A is area, C is the y-intercept and Z is the slope (regression coefficient).

What is the rivet-popper hypothesis?

It is an analogy by Paul Ehrlich comparing species to rivets holding an aeroplane together; loss of species (rivets) progressively weakens the ecosystem (aeroplane) until it collapses.

Differentiate between in situ and ex situ conservation.

In situ conservation protects species in their natural habitats (e.g., national parks), while ex situ conservation protects them outside their natural habitats (e.g., zoos and seed banks).

What are sacred groves and why are they important?

Sacred groves are forest patches protected by religious and cultural traditions; they help conserve many rare and threatened species in their natural state.

What is cryopreservation?

Cryopreservation is an ex situ technique of preserving gametes, tissues or embryos at very low temperatures (in liquid nitrogen at -196 degrees C) for future use.

Name an international convention for biodiversity conservation.

The Convention on Biological Diversity, signed at the Earth Summit in Rio de Janeiro (1992), is a key international convention for biodiversity conservation.

Biodiversity and its Conservation

Q: Name the components of the Evil Quartet.

Habitat loss and fragmentation, over-exploitation, alien species invasions and co-extinctions.

Q: Give two examples of in situ conservation strategies.

Biosphere reserves and national parks (also wildlife sanctuaries, sacred groves and biodiversity hotspots) are in situ conservation strategies.

Class 12 Biology · Biology · Chapter 13

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CBSE Class 12 · Biology

Genetics + Evolution: Unit VII, 20 marks

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CBSE Class 12 · Biology

Genetics + Evolution: Unit VII, 20 marks

Marks booster + cheatsheet: key concepts in 2 lines each, common traps
16 marks: Reproduction, Unit VI
12 marks each: Units VIII and IX
10 marks: Ecology, Unit X
13 chapters, with page numbers
Common traps, corrected

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Summary

This chapter discusses biodiversity, the variety and variability among living organisms and ecosystems, and the importance of conserving it. Biodiversity is described at three levels: genetic diversity (variation within a species), species diversity (variety of species) and ecological or ecosystem diversity (variety of habitats and communities). Patterns of biodiversity include the latitudinal gradient (diversity increases from the poles to the equator, with the tropics being richest) and the species-area relationship, expressed by Alexander von Humboldt as a rectangular hyperbola and a straight line on a logarithmic scale. The importance of biodiversity is explained through narrowly utilitarian, broadly utilitarian and ethical arguments, and the rivet-popper hypothesis illustrating ecosystem stability. Causes of biodiversity loss, the "Evil Quartet", include habitat loss and fragmentation, over-exploitation, alien species invasions and co-extinctions. Conservation strategies are classified as in situ (protection in natural habitats through biosphere reserves, national parks, wildlife sanctuaries, sacred groves and biodiversity hotspots) and ex situ (protection outside natural habitats through zoological parks, botanical gardens, seed banks, cryopreservation and in vitro fertilisation). The chapter concludes with international efforts and conventions, such as the Earth Summit and the Convention on Biological Diversity, that aim to ensure the sustainable use and equitable sharing of biological resources.

Levels of biodiversityPatterns of biodiversityImportance of biodiversityLoss of biodiversity and the Evil QuartetIn situ conservationEx situ conservation

Key terms

Biodiversity

The variety and variability of life forms at genetic, species and ecosystem levels in a given region.

Species diversity

The variety of species present in a region or ecosystem.

Endemism

The phenomenon of a species being restricted to and found only in a particular geographical area.

In situ conservation

The conservation of species in their natural habitats, such as in national parks and sanctuaries.

Ex situ conservation

The conservation of species outside their natural habitats, such as in zoos and seed banks.

Biodiversity hotspot

A region with a very high level of species richness and a high degree of endemism that is under threat.

Extra questions & answers

Try one from this chapter

Which of the following is NOT a level of biodiversity?

Flashcards & interactive practice