CBSE - X - Biology - Heredity and Evolution
define variation,heredity, genetic drift,organic evolution.
Evolution is a gradual and continuing process of change that occur over a period of time, due to slight variations in genetic compositions as well as changes in environment, leading to formation of new species.
Genetic drift is the random change in the frequency of genes or factors in a population over successive generations in a small population, presumably owing to chance rather than natural selection.
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