Chapter 13: Biodiversity and Conservation Short Questions | biology Class 12 CBSE

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Chapter 13: Biodiversity and Conservation Short Questions | biology Class 12 CBSE | ByteNotes.in

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Question 1

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What are the three levels of biodiversity? Give one example for each.

Genetic diversity refers to variation within a species, e.g., more than 50,000 genetically different strains of rice in India.
Species diversity refers to the variety of species in a region, e.g., the Western Ghats have greater amphibian species diversity than the Eastern Ghats.
Ecological diversity refers to diversity at the ecosystem level, e.g., India has greater ecosystem diversity than Norway due to its deserts, rainforests, mangroves, coral reefs and alpine meadows.

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Question 2

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Who coined the term 'biodiversity' and how is it defined?

The term 'biodiversity' was popularised by the sociobiologist Edward Wilson.
It describes the combined diversity at all levels of biological organisation, from macromolecules within cells to biomes.
It encompasses genetic, species and ecological diversity across the entire biosphere.

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Question 3

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State the global species diversity estimate given by Robert May and mention what percentage has been recorded so far.

Robert May placed the global species diversity at approximately 7 million species, which is considered a conservative and scientifically sound estimate.
According to IUCN (2004), about 1.5 million species have been described and recorded so far.
This means only about 22 per cent of the total species have been recorded; the remaining 78 per cent are yet to be discovered and described.

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Question 4

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Why is India considered one of the 12 mega diversity countries of the world?

Although India covers only 2.4 per cent of the world's land area, its share of global species diversity is an impressive 8.1 per cent.
India has recorded nearly 45,000 species of plants and twice as many — approximately 90,000 — species of animals.
India also has great ecosystem diversity with deserts, rain forests, mangroves, coral reefs, wetlands, estuaries and alpine meadows within its territory.

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Question 5

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Describe the latitudinal gradient in species diversity with examples.

Species diversity generally decreases as we move away from the equator towards the poles; tropics harbour more species than temperate or polar areas.
Colombia (near equator) has nearly 1,400 bird species, New York (41° N) has 105 and Greenland (71° N) has only 56 bird species.
India, located largely in tropical latitudes, has more than 1,200 species of birds, reflecting the pattern of higher diversity near the equator.

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Question 6

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Write the equation for species-area relationship and explain each component.

The equation is: log S = log C + Z log A, where S = species richness and A = area of the region studied.
Z is the slope of the regression line (regression coefficient) and C is the Y-intercept of the line.
On a logarithmic scale, the rectangular hyperbola relationship between species richness and area becomes a straight line described by this equation.

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Question 7

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What are the Z values in the species-area relationship and what do they signify?

For smaller areas (within a region), the Z value lies in the range of 0.1 to 0.2, regardless of the taxonomic group or geographic region.
For very large areas such as entire continents, the Z value is much steeper, ranging from 0.6 to 1.2 — for example, frugivorous birds and mammals in tropical forests show a slope of 1.15.
A steeper Z value means species richness increases more rapidly with increasing area at the continental scale than at local or regional scales.

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Question 8

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What is the 'rivet popper hypothesis'? Who proposed it?

The rivet popper hypothesis was proposed by Stanford ecologist Paul Ehrlich as an analogy to explain the importance of species in ecosystem functioning.
In the analogy, an airplane represents the ecosystem and the thousands of rivets holding it together represent individual species; passengers popping rivets represent humans causing species extinctions.
As more rivets are removed, the plane becomes dangerously weak; similarly, losing species — especially key ones that drive major ecosystem functions — progressively impairs ecosystem functioning.

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Question 9

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What are the four major causes of biodiversity loss collectively known as?

The four major causes of biodiversity loss are collectively called the 'Evil Quartet'.
These are: (i) habitat loss and fragmentation, (ii) over-exploitation, (iii) alien species invasions, and (iv) co-extinctions.
Among these, habitat loss and fragmentation is identified as the most important cause driving species to extinction.

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Question 10

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Explain co-extinction with an example.

Co-extinction occurs when the extinction of one species leads to the extinction of another species that is associated with it in an obligatory way.
When a host fish species becomes extinct, its unique assemblage of parasites that depend entirely on that host also meets the same fate.
Another example is coevolved plant-pollinator mutualism, where extinction of the plant leads inevitably to the extinction of its specific pollinator and vice versa.

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Question 11

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What is alien species invasion? Give two examples of damage caused by alien species.

Alien species invasion refers to the introduction of non-native species — intentionally or unintentionally — that become invasive and cause the decline or extinction of indigenous species.
The Nile perch introduced into Lake Victoria in east Africa led to the extinction of more than 200 species of ecologically unique cichlid fish.
In India, invasive weeds like carrot grass (Parthenium), Lantana and water hyacinth (Eichhornia) cause environmental damage and threaten native species; the African catfish Clarias gariepinus threatens indigenous catfishes in Indian rivers.

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Question 12

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What is the 'narrowly utilitarian' argument for conserving biodiversity?

The narrowly utilitarian argument holds that humans derive countless direct economic benefits from biodiversity — food (cereals, pulses, fruits), firewood, fibre and construction material.
Biodiversity also provides industrial products such as tannins, lubricants, dyes, resins and perfumes, all derived directly from nature.
More than 25 per cent of drugs currently sold worldwide are derived from plants, and 25,000 plant species contribute to traditional medicines used by native peoples, making biodiversity economically indispensable.

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Question 13

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What is 'bioprospecting'?

Bioprospecting refers to the exploration of molecular, genetic and species-level diversity to discover products of economic importance, especially medicinal compounds.
With increasing resources directed towards bioprospecting, nations endowed with rich biodiversity can expect to reap enormous economic benefits.
Many useful medicinal plants in tropical rainforests are yet to be explored, meaning their potential value remains untapped through bioprospecting.

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Chapter 13: Biodiversity and Conservation | Short Questions

What are the three levels of biodiversity? Give one example for each.

Who coined the term 'biodiversity' and how is it defined?

State the global species diversity estimate given by Robert May and mention what percentage has been recorded so far.

Why is India considered one of the 12 mega diversity countries of the world?

Describe the latitudinal gradient in species diversity with examples.

Write the equation for species-area relationship and explain each component.

What are the Z values in the species-area relationship and what do they signify?

What is the 'rivet popper hypothesis'? Who proposed it?

What are the four major causes of biodiversity loss collectively known as?

Explain co-extinction with an example.

What is alien species invasion? Give two examples of damage caused by alien species.

What is the 'narrowly utilitarian' argument for conserving biodiversity?

What is 'bioprospecting'?

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