HERIDITY AND VARIATION
Whenever an infant is born in a family, the relatives begin to wonder about the resemblance of the infant’s eyes, facial features, complexion, colour of hair with those of the parents, siblings and grandparents. The source of such resemblances and differences are in the “genes” that are passed down from parents to children and so on generation after generation. This inheritance of genes is termed ‘heredity’ the study of heredity is ‘Genetics’. New individual develop according to the genes inherited from their parents.
It is further observed that siblings from same parents are unique and differ from each other except the identical twins. Such differences are termed variations. Variation in a population is very important. It has survival value for the population. This is because if the environment changes, some individuals (variants) may be able to adapt to new situations and save the population from dying out. Variation arises due to mutation or sudden change in the genes. Variation also arises because genes get shifted and exchanged during meiosis’ at formation of gametes, giving rise to new gene combinations. At fertilization, there is random mixing of parental chromosomes. Such a source of variation which is most common is called recombination. Variation arises because of mutation and recombination.
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