Question

Define the terms (i) natural selection and (ii) genetic drift. How do they change the frequency of certain genes over generation in a population? ​

Answer 1

1. Natural selection - the process by which those animals and plants which are best suited to the conditions in which they live have more young and live longer.
2. Genetic drift - variation in the relative frequency of different genotypes in a small population, owing to the chance disappearance of particular genes as individuals die or do not produce.

Genetic drift is change in allele frequencies in a population from generation to generation that occurs due to chance events. To be more exact, genetic drift is change due to 'sampling error' in selecting the alleles for the next generation from the gene pool of the current generation.

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