Short Answers:- 1) Factors that lead to extinction 2) Human activities that thre

Question

Short Answers:-

1) Factors that lead to extinction

2) Human activities that threaten the survival of other species.

3) What are the two mechanisms of variation? Explain why variation in a population is important?

4) What does the scientific community value most in a scientific study? Why is a large sample size so important?

5) Explain how our microbiota might be associated with oncogenesis. How do microbes contribute to mutagenesis? Give an example of how a microbe might be beneficial early in life and detrimental later in life.

Explanation / Answer

Q. 1 : Extinction occurs when the last existing member of a given species dies. Following are possible factors of extinction:

1. Habitat destruction and degradation by deforestration, land use change pattern, chemical toxicity, etc

2. Over-exploitation: Increased human population lead to over-exploitation of resources for extraction, hunting, fishing, so much so that species can not cope with the growing demand.and hence, its populations diminish and ultimately to extinction.

2. Pollution: One of most anthoprogenic factor. that changes the natural habitats of species, e.g. a pond or a river may get polutted and water turns unfit for organisms growing in it.

3. Disease and epidemics also leads to extinction of species

4. Invasions of alien species: Non- native species that grows notorously and replaces the native species

5. Global climate change: Climate change have a profound impact on indigenous plants and animals. it may lead to increased sea water leve, change in isotherms, thereby disturbing the natural habotat of species.

6. Habitat Fragmentation that results in the formation of small populations also known as metapopulations which are prone to extinction.

7. Natural catastrophies: such as floods, hurricans, forest fires, glaciation, drought etc.

Q. 2:

Human activities that threaten the survival of other species are: Habitat destruction and degradation, introduction of alien invasive species, overexploitation of resources, phasing out large amounts of pollutants in different habitas, habitat fragmentation by construction of roads, railways dams etc.

Q. 3

The two important mechanisms of gentic variations that lead to morphological as well as physiological variations are Mutations (changes in the genetic material of an organisms) and Gene flow (transfer of genes from one population to another)

Variations develop such genotypes that increase the capability of an organism to survive and reproduce better than others and, hence, gain in relative gene frequency. In the absence of variations, species can not change with the changing environment that may be loss of habitat, scarcity of food, harsh fluctuation in temperature, and hence may extinct.

O. 4

Because small size samples show more errors or fluctuation.

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