Question

Which of the following terms applies to an allele when its frequency reaches a value of 0.0?

	A.	Natural selection
	B.	Loss
	C.	Fixation
	D.	Mutation

Answer 1

Ans.

The answer is (B) Loss

Explanation:

The measure of relative frequency of a variant of a gene or an allele on a particular gentic locus in a population is called as an Allele Frequency.In other words, it can be defined as the fraction of all those chromosomes that carry that allele in the given population.Genetic diversity of a species population can be understood by using the allele frequency in population genetics.

When allele frequencies change by chance alone, within a population, as a result of errors in sampling from generation to next generation, then this random process which can lead to large changes in population,over a short time period, is called as Genetic Drift. This genetic drift can lead to Loss of some alleles and the Fixation of some other allels in a population.It is dependent on effective population size and also on the frequency distribution of alleles at a population locus.

When the Allele frequency reaches a value of 1.0, then it is termed as Fixation, where all the individuals in the population will have the same particular allele at a locus.

&

When the Allele frequency reaches a value of 0.0, then it is termed as Loss, where all the individuals in the population has lost some allele at a locus.

Let us also understand what exactly the other answer options are:

(A) Natural Selection - It is basically a mechanism of evolution which results in the organisms adaptation to its environment by selectively reproducing changes in its genetic constitution. In a natural selection process, the organisms with traits favorable to them reproduces more,thus passing on these traits to their next generation,hence getting adapted to their environment over time.

(D) Mutation - Mutation is defined as a change in the sequence of DNA,occured either during the replication process of the DNA or as a result of other enviromental factors such as UV light,Chemical's,radiation etc.These changes in structure of a gene results in a variant gene formation, that can be transmitted from one generation to the subsequent generations.