Question

How do organism,whether reproduced asexually or sexually maintain a constant chromosome number through several generation?Explain with the help of suitable example.

Answer 1

In asexual reproduction the chromosome number is maintained constant by forming vegetative reproductive structures like the buds, bulbils etc or by processes like regeneration, Since these are formed from body structures the progenies have same number of chromosomes as that of the parent. Thus, the chromosome number is maintained constant

In prokaryotic cells like bacteria the chromosome number is maintained constant by a special type of division called binary fission.

During sexual reproduction formation of haploid cells called gametes and their fusion helps maintain constant chromosome number, here the cells forming the gametes undergo reduction division or meiosis where the chromosome number is reduced to half before zygote formation in diploid individuals (example humans, mango etc) or after zygote formation in haploid individuals (Bryophytes)