Question

For a trait to evolve (change) over time, what is the prerequisite that must be met?

a) All individuals must be homozygous at the genes responsible.

b) There must be heritable variability.

c) Competition must be momentarily relaxed.

d) Individuals must strive to change the trait during their lifetime.

Answer 1

Change in trait is the main charachterstic for evolution. Variability in trait is specific need for evolution of a charachter. Variation comes due to heterozygosity in alleles of a gene for a particular charachter. If individuals are homozygous then only in the presence of mutation some variation may occur which can lead to evolution. Hence option A is incoorect.

Competition in any case creates extra pressure. This pressure forces the individual to change their traits for better survival. Survival of fittest is the main reason of natural selection and existance of a species. If competition is relaxed then no betterment occurs. Hence option C is also incorrect.

If individual strive to change then no doubt there will be evolutiin of characters but those developed characters must also be passed to next generation. Inheretibility is the main reason for a character to develop and to remain persist in future generations. So option D is also incorrect because concept of inheretibility is absent here.

Heritable variability is the main charachterstic of evolution and developement over a period of time. Change in traits acquired during a course of time must be passed to future generation so that future generation can utilise those charachters for their better survival in adverse situations. Hence option B is correct.