Question

What are variations? Mention their types.

Answer 1

Hint: The phenomenon in which the progenies of an organism resembles their parents is called heredity. There are some characters of an organism that are different from their parents as well as other organisms. This creates variation.

Complete answer: Asexual reproduction is the method by which organisms reproduce in an asexual manner involving only a single parent. Note that it differs from sexual reproduction as the latter involves both parents. Keep in mind that all the offsprings produced by asexual reproduction are not only identical to the parent, but also to one another. It is sexual reproduction that brings in variation to the offsprings. Sexual reproduction involves the fusion of gametes from male and female parents. Gamete formation takes place by meiotic division. In meiotic division, crossing over of chromosome fragments takes place between homologous chromosomes. This induces recombination. Because of this progeny are different from their parents. A particular species is different from another in several characters. Organisms from the same species are also different in nature. All these come under the term variations.
Variation may be genotypic or phenotypic. Genotypic variations are caused by the differences in the number and structure of chromosomes. It may also occur when the genes present in these chromosomes are different. Phenotypic variations are the external variations seen in organisms in relation to their age, environment, and other factors. Know that genotypic variations can’t be identified morphologically. Genetic experiments need to be done for this but we can identify phenotypic variations by assessing morphological differences.

Note: Variations are also classified as continuous and discontinuous. In continuous variations, the character can have many different values between the two extremities. Human skin colour is an example as we have different tones to our skin from the darkest to the lightest. Discontinuous variations have limited choices for characters. For example, the sex of an animal can have only two choices in most cases. They are male and female.