Question

Which of the following is the Blastogenic variation?
A. Germ cell variation
B. Discontinuous variation
C. Somatogenic variation
D. Both A and B

Answer 1

Hint: In biology Variation refers to any difference between cells, individual organisms or groups of organisms of any species affected either by genetic differences (this is called genotypic variation) or by the effect of environmental issues on the expression of the genetic potentials (this is called phenotypic variation). Variation may be shown in physical appearance, behaviour, fertility, mode of reproduction, metabolism, learning and mental ability and other noticeable or measurable characteristics.

Complete answer:
Here the correct answer is Option D - Both A and B. That means Germ cell variation and Discontinuous variation both are blastogenic variations.
Explanation –
Option A - Germ cell variation: A germinal mutation or germline mutation is any detectable variation within germ cells (germ cells are the cells that, when they are fully developed they become ovum and sperm). The only mutations that can be passed on to the next generation are the mutations in these germ cells, when either a mutated sperm or ovum come together to form a zygote.
Option B - Discontinuous variation: A characteristic of any species with only a limited number of possible values displays the discontinuous variation. Human blood group is a perfect example of discontinuous variation. In the ABO blood group system there are only four blood groups possible and they are A, B, AB or O. We also get our blood group from our parents.

Additional Information:
Option C - Somatogenic variation: Somatogenic variations are due to external impacts upon the body of the organism. These variations are not heritable and not transmitted to the next generation and are lost with the death of that particular organism. While blastogenic variations happen in the germ cells of the organisms and have no external influence, they also inherit into the next generation.
So, Option C ‘Somatogenic variation’ is not the correct answer.

Note:
Genotypic variations are instigated by changes in number or structure of chromosomes or by variances in the genes carried by the chromosomes. Body form, Eye colour and disease resistance power are genotypic variations. Organisms with multiple sets of chromosomes are called Polyploids. Many common plants have two or more times the normal digit of chromosomes and new species may be born with this type of variation. A variation can’t be recognized as genotypic variation by observation of the organism: breeding experiments have to be performed under skillful environmental conditions to identify whether the alteration is inheritable or not.