Q. 1. Briefly mention about—
(a) Genetic diversity,
(b) Species diversity,
(c) Ecological diversity.
Ans. (a) Genetic diversity:
The occurrence of single species in high diversity at the genetic level over its distributional range is called as genetic diversity.
Such as in Rauwolfia vomitoria in Himalaya region, 50,000 varieties of rice, 1,000 varieties of mango in India.
(b) Species diversity:
The occurrence of diversity as the species level in a geographical region is called species diversity, e.g. western ghats have more amphibian species diversity than in eastern ghats.
(c) Ecological diversity:
A geographical region having different ecosystems will have more ecologically diverse organisms one having one or two types only. For example, India has more ecological diversity than Norway.
Q. 2. Explain with examples—latitudinal gradients.
Ans. The decrease in the species diversity from equator towards the poles is latitudinal gradient in diversity. This can be justified by following examples:
(i) Colombia located near equator has nearly 1,400 species of birds, New York at 41 °N has 105 species and Greenland at 71 °N has 56 species only. India has 1,200 species.
(ii) Equador’s forest has upto 10 times more species than mid west of USA for vascular plants.
Q. 3. Give three hypotheses for explaining why tropics show greatest levels of species richness.
Ans. The following three hypothesis for greatest levels of species richness are—
It is the function of time. The tropical latitudes have remained undisturbed for millions of years and had a long time for evolution among species diversification as compared to temperate regions that frequented for glaciations in past.
(b) Tropical environment:
It is more constant, less seasonal and predictable, than the temperate ones. This provides rich specialization and leads to greater species diversity.
(c) Solar energy:
There is presence of more solar energy and it contributes more productivity and in turn more diversity.
Q. 4. Study the following plot.
Answer the following:
(i) Which line/plot describes the species-area relationship on a logarithmic scale? Give the equation also.
(ii) What is the shape of curve for species richness and area for a wide variety of taxa?
(iii) What is the value of Z in a region and continent?
(iv) What does steeper slope of Z mean?
Ans. (i) The straight line represents the relationship. The equation is—Log S = Log C + Z Log A
(ii) Rectangular hyperbola.
(iii) Z value in a continent lies between – 0.6 to 1.2. Z value in a continent lies between 0.6 to 1.2.
(iv) It means more species richness relationship.
Q. 5. How is biodiversity important for ecosystem functioning?
Ans. Biodiversity is very important for the ecosystem functioning and its stability. It also is responsible for the health of the ecosystem but the very survival of human in the ecosystem on this planet.
Q. 6. How is a stable community identified?
Ans. The following points if observed suggest that the community is stable—
(a) It must not show too much variation in the productivity from year-year.
(b) It must be resistant or resisetent to occasional disturbances caused by nature and man-made.
(c) It must be resistant to invasions by alien species.
Q. 7. How many mass extinction of species are there on records since the origin and diversification of life on earth? How is the present episode different? What is the result of loss of biodiversity in a region?
Ans. There were 5 episodes of mass extinction of species. The present sixth episode is in progress.
The current rates of extinction is estimated to be faster than the pre-human times because of our activities. It is estimated to be faster 100-1000 times. General loss is:
(a) Decline to plant production.
(b) Lowered resistance to environmental disturbances such as droughts.
(c) Increased variability in certain ecosystem processes.
Q. 8. Briefly give the views regarding the reasons for conserving biodiversity.
Ans. There are the following views:
(a) Narrowly utilitarian:
We humans derive countless direct economic benefits from nature. Such as food, medicines and many more utility things.
Nations with rich biodiversity can expect to reap enormous benefits from the increasing resources put into bioprospecting.
(b) Broadly utilitarian:
It says that biodiversity plays a major role in many ecosystem services that nature provides. There are many intangible benefits that we derive from nature, including aesthetic pleasures.
(c) Ethical values:
All living beings that share this planet have equal right to live as do humans. We must realize that every species has an intrinsic value, even if we do not have any current economic value. We have to maintain the biological legacy in good order for future generations.
Q. 9. What are sacred groves? What is their role in conservation?
Ans. India has a history of religious and cultural traditions that emphasized protection of nature.
In many cultures, tracts of forests are set aside and trees, animals are given total protection. Such forests are called sacred groves.
Such forests are called sacred groves which help us to preserve, protect the forests, wildlife and other rare, threatened and vulnerable species.
Q. 10. Among the ecosystem services are control of floods and soil erosion. How is this achieved by the biotic components of the ecosystem?
Ans. Control of floods and soil erosion are done by preserving the forests. There must be a balance between the plants and animals to maintain the biodiversity.
Q. 11. The species diversity of plants (22 per cent) is much less than that of animals (72 per cent). What could be the explanations to how animals achieved greater diversification?
Ans. The animals have higher per cent than the species diversity of plants because they are mobile and move from one place to another.
They moved to different habitats/ecosystem and developed species diversity.
Q. 12. Can you think of a situation where we deliberately want to make a species extinct? How would you justify it?
Ans. Human health, followed by health of plants and animals of economic use. The health of human, plants and animal species is always in danger due to pathogens, and vectors, secondary or primary hosts.
For the welfare of human, we want to deliberately make such pathogenic species extinct. This will ensure, the pathogenic diseases free human life and animal life.