Question

What is variation? Give an example.

Answer 1

Variation:

1. Variation exists among the individuals of one species. Variation is also due to crossing over, recombination, mutation & environmental effects on expression of genes present on chromosomes.
2. Types of variation:
   1. Somatogenic Variations: These are variations that affect the somatic or body cells of the organisms. They are also called the modifications or acquired characters since they are acquired by the individual during their lifetime. Factors causing it are:
      1. Environment: The environmental factors are the medium, light, temperature, nutrition, wind, water supply, etc. Such environmental factors bring about changes in the phenotype of the individual.
      2. Conscious efforts: Modifications that occur due to conscious efforts are observed only in those animals that have intelligence.
   2. Germinal or Blastogenic Variations:
      1. They are produced in germ cells of an organism & are inheritable.
      2. They may be already present in the ancestors or may be formed suddenly.
3. Horn is the character of cattle whose expression is based on the expression of the gene related to the horns.
4. If such genes of horn get suppressed in some cattle, then the cattle become hornless.