Question

Answer the following:

(i) Define variation.

(ii) How are heritable variations produced in an organism?

(iii) What is the source of variations in asexually-reproduced organisms?

Answer 1

(i)

Variation:

• The differences observed between the individuals belonging to a certain species are known as variations.
• Though the children inherit traits from their parents, they do not look exactly like them because of the variations.
• For example, though a mother has straight hair, her son can have curly hair.
• Marked variations are found in sexually reproducing organisms

(ii)

Heritable variation:

• The heritable variations are those variations that are inherited from the parents by the progeny.
• Heritable variations are produced when the progeny is developed from sexual reproduction.

Ways through which heritable variations arise:

• The heritable variation arises because of mutation and recombination occurred between homologous chromosomes
• Some other reasons are random mating and random fertilization.

(iii)

Asexual reproduction:

• Asexual reproduction produces progeny that are identical copies of the parents.
• This reproduction does not involve sex cells or gametes.
• Replication of DNA is followed by splitting of the mother cell into two halves that are exact copies of the mother cell.

Ways through which variations arise in asexual reproduction:

• Sometimes asexual reproduction also brings minor variations. This can occur due to improper copying of DNA.