Question

Withthe help of the following pattern briefly explain the reason for a) DNA Stability b) Variation phenomenon found in the successive generation of species.

Answer 1

a) Cell division is a very precisely regulated process. DNA is organized as chromosomes during cell division, which is precisely duplicated so that progeny cells receive an equal amount of DNA ( during mitosis ) or half amount ( during meiosis ). This diagram shows homologous chromosomes that are separated during meiosis.

b) Homologous chromosomes undergo recombination i.e. exchange of genetic material. Later they are separated and independently assorted in chromosomes resulting in variation in successive generations.