NEET Biology Biodiversity and Conservation MCQs Set 09

Answer: (b) Edward Wilson

Explanation:
1. Sociobiologist Edward Wilson popularised the term biodiversity.

Teacher's Note:
1. Remember the name-concept pairs: Wilson for the term, May for the global estimate, Myers for hotspots and Ehrlich for the rivet popper hypothesis.

Answer: (c) genetic diversity

Explanation:
1. Variation within a single species in the amount of a chemical is variation at gene level, that is genetic diversity.

Teacher's Note:
1. Same species with different traits points to genetic diversity. Different species in a region points to species diversity.

Answer: (b) a wide variety of ecosystems such as deserts, mangroves, coral reefs and alpine meadows

Explanation:
1. Ecological diversity is the variety of communities and ecosystems. India has deserts, rain forests, mangroves, coral reefs, wetlands, estuaries and alpine meadows.

Teacher's Note:
1. Do not confuse ecosystem diversity with the number of species. It is about the variety of habitats.

Answer: (b) 7 million

Explanation:
1. May's conservative and scientific estimate is about 7 million species. Slightly over 1.5 million have been described.

Teacher's Note:
1. 1.5 million is the described number, 7 million is May's estimate, and 20 to 50 million is the higher range of other estimates.

Answer: (c) Insects

Explanation:
1. Insects make up more than 70 per cent of animal species, so they are the most species-rich group.

Teacher's Note:
1. Out of every 10 animals, about 7 are insects. This is a frequently tested fact.

Answer: (a) 2.4 per cent of world land area and about 8.1 per cent of global species

Explanation:
1. India has only 2.4 per cent of the land area but about 8.1 per cent of species diversity.

Teacher's Note:
1. Note the order carefully: 2.4 is for land area and 8.1 is for species.

Answer: (c) Species diversity generally decreases from the equator towards the poles

Explanation:
1. With few exceptions, tropics have more species than temperate and polar regions. For example, Colombia has about 1,400 bird species and Greenland about 56.

Teacher's Note:
1. Remember the pattern with the bird examples: Colombia, New York, Greenland.

Answer: (d) Tropical regions have fewer predators

Explanation:
1. The three accepted reasons are long evolutionary time, a constant predictable environment that promotes niche specialisation, and greater solar energy. Fewer predators is not one of them.

Teacher's Note:
1. Learn the three reasons as time, stability and energy.

Answer: (b) rectangular hyperbola

Explanation:
1. The relation S = C A^Z gives a rectangular hyperbola on arithmetic axes and a straight line on a log scale.

Teacher's Note:
1. Humboldt first described the pattern: richness rises with area, but only to a limit.

Answer: (d) the slope of the line

Explanation:
1. Z is the slope (regression coefficient); C is the Y-intercept, S is species richness and A is area.

Teacher's Note:
1. Z is 0.1 to 0.2 for most regions and 0.6 to 1.2 for very large areas such as continents.

Answer: (c) 0.6 to 1.2

Explanation:
1. For small to medium areas Z is 0.1 to 0.2, but for continents the slope is steeper, 0.6 to 1.2.

Teacher's Note:
1. The slope is steeper on larger areas because new species keep appearing as new habitats are included.

Answer: (b) had less year-to-year variation in total biomass

Explanation:
1. Tilman found that plots with greater diversity showed less year-to-year variation in total biomass and higher productivity.

Teacher's Note:
1. More species means a more stable community. This supports why conserving biodiversity matters.

Answer: (b) species

Explanation:
1. The aeroplane is the ecosystem and each rivet is a species. Removing rivets is extinction.

Teacher's Note:
1. Rivets on the wings are the key species that drive major functions.

Answer: (c) 784

Explanation:
1. The list documents 784 extinctions (338 vertebrates, 359 invertebrates and 87 plants).

Teacher's Note:
1. Check that 338 + 359 + 87 = 784.

Answer: (d) Rhesus monkey

Explanation:
1. Dodo (Mauritius), Quagga (Africa) and Thylacine (Australia) are extinct, as are Steller's sea cow and three tiger subspecies. The rhesus monkey is not extinct.

Teacher's Note:
1. Learn each extinct animal with its region.

Answer: (c) Amphibians

Explanation:
1. Extinctions are not random across taxa. Amphibians are especially vulnerable, with about 32 per cent threatened.

Teacher's Note:
1. Percentages threatened: amphibians 32, gymnosperms 31, mammals 23, birds 12.

Answer: (b) the Evil Quartet

Explanation:
1. Habitat loss and fragmentation, over-exploitation, alien species invasions and co-extinctions form the Evil Quartet.

Teacher's Note:
1. Habitat loss is the most important of the four.

Answer: (b) cultivating soya beans and grazing beef cattle

Explanation:
1. The forest is cut for soya cultivation and converted to grassland for beef cattle.

Teacher's Note:
1. Tropical rain forests have shrunk from over 14 per cent to about 6 per cent of land area.

Answer: (b) over 200 species of native cichlid fish

Explanation:
1. The predator Nile perch eliminated an ecologically unique group of more than 200 native cichlid species.

Teacher's Note:
1. This is an example of the alien species invasion arm of the Evil Quartet.

Answer: (a) Extinction of a host fish and its parasites

Explanation:
1. When a species goes extinct, species obligately associated with it, such as its parasites or a coevolved pollinator, also go extinct.

Teacher's Note:
1. Co-extinction involves two species that depend on each other.

Answer: (a) control pollution

Explanation:
1. It was introduced to reduce pollution, but it clogged water bodies and killed many aquatic organisms.

Teacher's Note:
1. Introductions made for a good purpose can still become invasive.

Answer: (c) Seed bank

Explanation:
1. Zoos, botanical gardens, gene banks, seed banks and cryopreservation are ex situ. National parks, sanctuaries, biosphere reserves and sacred groves are in situ.

Teacher's Note:
1. Ex situ means outside the natural habitat.