NEET Biology Biodiversity and Conservation MCQs Set 07

Answer: (b) Beetles

Explanation:
1. Insects are the most species-rich group of animals, and among the options beetles are the largest group of insects.

Teacher's Note:
1. Beetles alone are more than 70 percent of known insect species in many estimates.
2. Orchids are the most diverse plant family among the options but have fewer species.

Answer: (a) Genetic diversity

Explanation:
1. Variation within one species (Rauwolfia vomitoria) across different Himalayan ranges is genetic diversity.
2. It also shows in the amount of reserpine produced by different populations.

Teacher's Note:
1. Genetic diversity is variation within a species.
2. India has over 50,000 genetically different strains of rice and 1000 of mango.

Answer: (b) 7 million

Explanation:
1. Robert May's conservative estimate of global species is about 7 million.

Teacher's Note:
1. The IUCN (2004) records about 1.5 million species described.
2. Only part of the estimate has been named and described.

Answer: (c) 7 out of 10 animals

Explanation:
1. Insects make up about 70 percent of all animal species, so 7 out of 10 animals are insects.

Teacher's Note:
1. Insects are the most diverse animal group.
2. Mammals are fewer than 6000 species.

Answer: (b) Mammals

Explanation:
1. Among vertebrates, mammals have the fewest species (about 5,500) while birds, reptiles and amphibians are more diverse.

Teacher's Note:
1. Fishes are the most diverse vertebrate group.
2. Mammals are the most studied but not the most diverse.

Answer: (c) Microbial species

Explanation:
1. Microbes are tiny, mostly cannot be cultured in the lab, and are hard to identify by structure.
2. So conventional taxonomic methods are not suitable for them and molecular methods are used.

Teacher's Note:
1. Fewer than 1 percent of microbes can be cultured.
2. DNA sequence and biochemical tools help in identifying them.

Answer: (d) 2.4, 8.1

Explanation:
1. India has only 2.4 percent of the world's land area but about 8.1 percent of the global species diversity.
2. So India is one of the 12 mega-diversity countries.

Teacher's Note:
1. Mega-diversity countries together hold a large share of species.
2. India has high ecosystem and species diversity.

Answer: (b) log S = log C + Z log A

Explanation:
1. On a log scale, species richness S and area A give a straight line: log S = log C + Z log A.
2. Z is the slope and C is the y-intercept.

Teacher's Note:
1. Alexander von Humboldt first described the species-area relationship.
2. The graph is a rectangular hyperbola on arithmetic scale.

Answer: (d) 0.6 to 1.2

Explanation:
1. For very large areas such as continents the slope Z is steeper, in the range of 0.6 to 1.2.
2. For smaller areas Z lies between 0.1 and 0.2.

Teacher's Note:
1. Z is the same for any region over small areas.
2. Z is steeper for continents because there are more species per unit area added.

Answer: (d) Paul Ehrlich

Explanation:
1. The rivet popper hypothesis was proposed by Paul Ehrlich.
2. Species are compared to rivets on an aeroplane wing: losing one may be harmless, but losing many weakens the whole.

Teacher's Note:
1. Another view, by David Tilman, shows that more diverse plots are more productive.
2. Both support conserving biodiversity.

Answer: (a) 2000

Explanation:
1. Human colonisation of the tropical Pacific islands led to extinction of more than 2000 species of native birds.

Teacher's Note:
1. Islands are fragile with many endemic birds.
2. Human arrival brought hunting and introduced predators.

Answer: (d) a(iii), b(ii), c(iv), d(i)

Explanation:
1. Thylacine: Australia. Dodo: Mauritius. Quagga: Africa. Steller's sea cow: Russia.
2. So a-iii, b-ii, c-iv, d-i.

Teacher's Note:
1. These are well known extinct animals.
2. Extinction in the last 500 years was mostly human caused.

Answer: (b) A – 784, B – 500

Explanation:
1. The IUCN Red List (2004) documents the extinction of 784 species (including 338 vertebrates, 359 invertebrates and 87 plants) in the last 500 years.

Teacher's Note:
1. The list is published by IUCN.
2. Extinction rates today are 100-1000 times the natural rate.

Answer: (d) Increased endemism

Explanation:
1. Loss of biodiversity lowers plant production, reduces resistance to environmental perturbations (drought) and increases variability in ecosystem processes.
2. It does not increase endemism.

Teacher's Note:
1. Endemism means being restricted to one region.
2. Loss of species cannot increase it.

Answer: (c) A– 23, B– 31

Explanation:
1. About 23 percent of mammal species and 31 percent of gymnosperm species are threatened with extinction.

Teacher's Note:
1. Also about 32 percent of amphibians and 12 percent of birds.
2. These threats are mostly human caused.

Answer: (c) Biodiversity losses

Explanation:
1. The Evil Quartet is the group of four major causes of biodiversity loss: habitat loss and fragmentation, over-exploitation, alien species invasion and co-extinctions.

Teacher's Note:
1. Habitat loss is the most important cause.
2. Tropical rain forests have shrunk to a small part of their former area.

Answer: (c) Habitat loss and fragmentation

Explanation:
1. Habitat loss and fragmentation is the most important cause of extinction of animals and plants.

Teacher's Note:
1. The Amazon forest is cleared for soya and cattle.
2. Fragmentation hurts animals needing large territories.

Answer: (b) Nile perch

Explanation:
1. Introduction of the Nile perch into Lake Victoria caused the extinction of more than 200 species of cichlid fish.

Teacher's Note:
1. This is an example of alien species invasion.
2. Other examples: Lantana, water hyacinth and African catfish (Clarias gariepinus) in Indian waters.

Answer: (a) Co-extinction

Explanation:
1. When a host species becomes extinct, the parasites that depend on it also die out.
2. This is co-extinction.

Teacher's Note:
1. A plant and its pollinator can also co-extinct.
2. It is one part of the Evil Quartet.

Answer: (b) 25

Explanation:
1. More than 25 percent of the drugs sold worldwide come from plants.

Teacher's Note:
1. About 25,000 species of plants are used in medicines.
2. Bioprospecting looks for such products.