Botany MCQs for NEET — Practice Questions with Answers

The NCERT text lists three hypotheses: '(a) Tropical latitudes have remained relatively undisturbed for millions of years and thus had a long evolutionary time for species diversification, (b) Tropical environments, unlike temperate ones, are less seasonal, relatively more constant and predictable. Such constant environments promote niche specialisation and lead to a greater species diversity and (c) There is more solar energy available in the tropics, which contributes to higher productivity; this in turn might contribute indirectly to greater diversity.' Option o3 is contradictory to the given hypotheses, particularly (c).

According to the NCERT text: 'Such constant environments promote niche specialisation and lead to a greater species diversity'.

The NCERT text states: 'There is more solar energy available in the tropics, which contributes to higher productivity; this in turn might contribute indirectly to greater diversity.'

The text mentions: 'India, with much of its land area in the tropical latitudes, has more than 1,200 species of birds.'

The general principle of latitudinal gradient states that species diversity decreases from the equator towards the poles. A polar desert represents the highest latitudes, hence the least diversity among the options.

One of the hypotheses given in the text is: 'Tropical latitudes have remained relatively undisturbed for millions of years and thus had a long evolutionary time for species diversification'.

According to the latitudinal gradient, diversity decreases away from the equator. 41° N is farther from the equator than 23.5° N, so biodiversity would be expected to be lower. The example of New York (41° N, 105 species) vs. Colombia (near equator, 1400 species) supports this.

Genetic diversity refers to the diversity at the genetic level within a single species. The example of Rauwolfia vomitoria showing variations in the potency and concentration of reserpine across its distributional range is a direct illustration of genetic diversity, as stated in the NCERT text: 'A single species might show high diversity at the genetic level over its distributional range. The genetic variation shown by the medicinal plant Rauwolfia vomitoria growing in different Himalayan ranges might be in terms of the potency and concentration of the active chemical (reserpine) that the plant produces.'

According to the NCERT text: 'Although India has only 2.4 per cent of the world’s land area, its share of the global species diversity is an impressive 8.1 per cent. That is what makes our country one of the 12 mega diversity countries of the world.'

Ecological diversity refers to the diversity at the ecosystem level. The NCERT text states: 'At the ecosystem level, India, for instance, with its deserts, rain forests, mangroves, coral reefs, wetlands, estuaries, and alpine meadows has a greater ecosystem diversity than a Scandinavian country like Norway.' This direct comparison highlights the variety of ecosystems within India.