Biology 12 Biodiversity and Conservation chapter 16 – Exercise,
Q 1. Name the three components of biodiversity.
Ans 1. Three important components of biodiversity are: genetic diversity, species diversity and ecosystem diversity.
Q 2. How do ecologists estimate the total numbers of species present in the world?
Ans 2. Ecologists make a statistical comparison of the species richness of exhaustively studied groups of insects of the temperate and tropical regions and extrapolate this ratio to other groups of animals and plants to calculate gross estimate of the total number of species existing on the earth.
Q 3. Give three hypotheses for explaining why tropics show greatest levels of species richness.
Ans 3. 3 hypotheses why tropics shows greatest levels of species richness.
- The tropical environmental is older, allowing more time for the evolution of much larger number of fauna and flora.
- There is more solar energy available in the tropics contributing to higher productivity and this indirectly contributing to greater diversity.
- Rate of extinction of species is low. This is so because the environment that prevails in the tropics is nearly constant.
Q 4. What is the significance of the slope of regression in species-area relationship?
Ans 4. When analysis of species-area relationships is done among small areas, the values of slopes of regression are remarkably similar regardless of the taxonomic group of the region. However, when such analysis is done among very large areas. i.e., continents, then the slope of regression would be much steeper.
Q 5. What are the major causes of species losses in a geographical region?
Ans 5. Major causes of species losses in geographical region are hunting, forest fires, destruction of habitats and fragmentation, and introduction of exotic species.
How is biodiversity important for ecosystem functioning?
ans 6. Rich biodiversity provides alternatives available at each trophic level. All organisms are linked in food chains and interact with their abiotic environment in such a way so as to keep the natural cycles going and make the ecosystem self-sustaining units. Disappearance of any link in a food chain will not affect the ecosystem as other alternative are there.
Q 7. What are sacred grooves? What is their role in conservation?
Ans 7. Sacred grooves are the sacred forest patches around places of worship. These are held in high esteem by tribal communities/state or central government. Tribal do not allow to cut even a single branch of tree in these sacred grooves. This is the reason why many endemic species flourish in these regions.
Q 8. Among the ecosystem services are control of floods and soil erosion. How is this achieved by the biotic components of the ecosystem?
Ans 8. Plants play a vital role in the control of floods and soil erosion. Their roots bind the particles firmly and in the way they do not allow the top soil to be drifted away by winds or moving water. Roofs of plants also make the soil porous and allow water to go into soil.
Q 9. The species diversity of plants (22%) is much less than that of animals (72%). What could be the explanations to know animals achieved greater diversification?
Ans 9. Most animals possess simple or complex nervous system to control and coordinate various activities they possess receptors to receive environmental stimuli and show response against them. Most of their responses are adaptive and ensure their survival in changing environmental conditions. They, therefore, have evolved to reveal much higher species diversity than plants who do not possess nervous system and respond differently against environmental stimuli.
Q 10. Can you think of a situation where we deliberately want to make a species extinct? How would you justify it?
Ans 10. We are truing to eradicate disease causing organisms (e.g., polio virus) from this world to make this world disease free. Since, such microorganisms are harmful to the human society, such attempt is justified. Further, such microorganisms are not essential components (produces or decomposers) of any ecosystem and losing one or few such organisms would not affect the functioning of ecosystems.