Test: Biodiversity & Conservation - 1 - NEET MCQ

The off-site or the protection and conservation of species (genetic resources) outside their natural habitat (populations of plant or animal species) is known as ex-situ conservation. Areas such as botanical gardens, zoos, Gene banks, Tissue culture banks are the places were ex-situ conservation is done.

If all members fo a host species die the parasite that obtain their food from the particular host also die off due to lack of food. This represent co-existence of species.

When we will move away from the equator towards poles there is a gradual decrease in the species diversity. This is because climatic condition becomes gradually adverse as we move from equator to poles.

Wetlands are areas where water is the primary factor controlling the environment and the associated plant and animal life. They occur where the water table is at or near the surface of the land, or where the land is covered by water.

India has about 50,000 type of rice and 1000 types of varieties of mango. This thigh level of diversity indicates very high genetic diversity and one of the largest in the world.

Species area relationship is the relationship between the area and the particular habitat. It is dependent on immigration, extinction and clustering etc. It was first studied by Alexander Von Humbolt.

NCERT Line: According to the International Union for Conservation of Nature and Natural Resources (IUCN) (2004), the total number of plant and animal species described so far is slightly more than 1.5 million, but we have no clear idea of how many species are yet to be discovered and described. Estimates vary widely and many of them are only educated guesses.

Those species whose number of individuals is greatly reduced to a critical level and are at a high risk of extinction in the wild are known as endangered species. Some examples of endangered species are Brown spider monkey, Bengal tiger, Ganga river dolphin, Indian Rhino, Black buck, etc.

NCERT line: Initially 25 biodiversity hotspots were identified but subsequently nine more have been added to the list, bringing the total number of biodiversity hotspots in the world to 34.

When a graph is drawn to compare the relationship between species richness and area for wide variety of texa, the graph appears to be a rectangular hyperbola.

• The species of plants contribute to the traditional medicines used by native peoples around the world are approximately 25,000.
• Some examples of traditional plants used for medicinal purposes are ginger, garlic, chamomile, tulsi, etc.

Cryopreservation is the method of preserving living organisms or their parts at extremely low temperature. To preserve seeds that rapidly lose viability and cannot survive desiccation are preserved by this method.

NCERT Line: Now gametes of threatened species can be preserved in viable and fertile condition for long periods using cryopreservation techniques, eggs can be fertilised in vitro, and plants can be propagated using tissue culture methods.

The impacts of introducing a non-native or invasive species to an ecosystem will vary depending on a number of factors.

In some instances, the introduced species may not survive. If there is no ecological niche for the species to fill or the species cannot adapt to fill a different ecological niche, the species will likely go extinct relatively quickly at the local level.

However, if the species is a generalist, or a species able to thrive in a variety of environments and consume many food sources, that species will likely do well. If the ecosystem has reached its stable state, this means that the invasive species will have to replace a native species. No two species can share the same ecological niche, thus one will be better adapted and survive. If the invasive species is better adapted, it will out compete the native species.

If the species reproduces quickly, it is also more likely to thrive in a new ecosystem. If it can reproduce and grow faster than its competitor, it will eventually out compete that species.

Typically, invasive species harm an ecosystem. For example, the Burmese python is found in the US but it isn't supposed to be here. These snakes were likely released by humans and were pets at one time. The environment is suitable for them and they have adapted to the area.

Introducing a new species can also introduce any diseases that species has. These new diseases can spread to other native species and negatively affect them.

Introducing exotic species into new areas will increase competition for food and space. Sometimes, exotic species brings disease along with them. Exotic species in new area do not lead to extinction of native species.

NCERT Line: Adding to the grim scenario of extinctions is the fact that more than 15,500 species world-wide are facing the threat of extinction. Presently, 12 per cent of all bird species, 23 per cent of all mammal species, 32 per cent of all amphibian species and 31per cent of all gymnosperm species in the world face the threat of extinction.

• The Amazon rainforest is the world’s largest tropical rainforest and is also known as the Amazon Jungle or Amazonia.
• Approximately 20 percent of the total oxygen in the Earth’s atmosphere is released by the Amazon forest by the process of photosynthesis.

The organisms that has been completely eliminated or died out from earth are called extinct organisms. For example Dodo.

In general, loss of biodiversity in a region may lead to (a) decline in plant production, (b) lowered resistance to environmental perturbations such as drought and (c) increased variability in certain ecosystem processes such as plant productivity, water use, and pest and disease cycles.

Amzonian rain forests are called as lungs of forest because it contains different kinds of vegetation that purify the atmosphere of the earth.

• More than 70 per cent of all the species recorded are animals, while plants (including algae, fungi, bryophytes, gymnosperms and angiosperms) comprise no more than 22 per cent of the total.
• Among animals, insects are the most species rich taxonomic group, making up more than 70 per cent of the total.

To determine the correct statements, let's analyze each one:

- Statement i: Correct. India's share of global species diversity is indeed 8.1% while covering only 2.4% of the land area.

- Statement ii: Correct. The text states that nearly 45,000 species of plants and twice as many animals have been recorded; this means there are about 90,000 animal species documented.

- Statement iii: Correct. The text supports this claim by mentioning that only 22% of total species have been recorded globally.

- Statement iv: Incorrect. The text estimates that there are probably more than 100,000 plant species yet to be discovered, not less.

Thus, the correct statements are i, ii, and iii, leading to the conclusion that Option B is correct.

The correct statements are i, ii, and iii.

1. Statement i is correct because the tropics have been relatively undisturbed for millions of years, allowing for more time for species diversification compared to temperate regions that have faced frequent glaciations.

2. Statement ii is also correct since the less seasonal and more stable environments in the tropics allow for niche specialization, thus enhancing species diversity.

3. Statement iii is correct as well; the greater solar energy availability in tropical regions contributes to higher productivity, which supports a wider range of species.

4. Statement iv is incorrect because polar regions have been significantly affected by glaciation events, leading to lower species diversity compared to tropical regions.

Therefore, the accurate answer is Option A: i, ii, and iii.

- Statement i is correct as the introduction of the Nile perch into Lake Victoria led to the extinction of over 200 species of cichlid fish.

- Statement ii is incorrect because invasive weed species like Lantana and water hyacinth are known to threaten native species and ecosystems.

- Statement iii is correct as co-extinctions occur when the extinction of one species, such as a host fish, leads to the extinction of its obligate parasites or mutualistic partners.

- Statement iv is incorrect because the introduction of Clarias gariepinus has been illegal and poses a threat to indigenous catfish populations.

Thus, the correct statements are i and iii, making option A the correct answer.

• The Assertion is true because various direct economic benefits, such as food, medicine, and materials, come from biodiversity.
• The Reason is also true; however, it does not explain the Assertion completely, as it focuses only on medicinal products and ignores other significant economic benefits derived from biodiversity.
• Therefore, while both statements are correct, the Reason does not adequately explain why conserving biodiversity is essential for economic benefits overall.

The Convention on Biological Diversity aimed to address the urgent need for global action to conserve biodiversity and promote its sustainable use.