Question

Which of the following is NOT a potential source of new alleles in a population?

	A.	Horizontal (gene) transfer
	B.	Gene duplication
	C.	Natural selection
	D.	Gene flow
	E.	Mutation

Which of the following is true about genetic drift?

	A.	It requires selection of adaptations in order to occur.
	B.	It causes isolated populations to become more similar over time.
	C.	It has the greatest effect in small populations.
	D.	It operates more rapidly in large populations.
	E.	It results from exchange of genetic material between populations.

Answer 1

Answers :

1. Inorder to answer this question let us analyze each of the given options with the given logic which is identification of potential source of new alleles in a population. We must first understand that evolution plays a major role when it comes to creation of new alleles in a population. Mutation is the best choice when it comes to creation of new alleles in a gene pool. This is because any sudden change in the gene may lead to creation of a new gene which could be passed on to the next generation. The concept of natural selection also aids in creation of new alleles because it brings about an evolutionary change and prefers the genotype which could mate and survive for many years. Gene flow as the name suggests is the transfer of gene from one population to another. But to understand whether it creates a new allele, we must note that if the gene flow happens within a population and not in a distant population then there are increased chances of genetic variation. The concept of evolution is once again applied in case of gene duplication which is nothing but chromosomal duplication for production of new genetic material through molecular evolution. Hence we infer that mutation, natural selection, gene flow and gene duplication are all great potential sources of new alleles in a population. Now left with the first option which is horizontal gene transfer. The concept of horizontal transfer is nothing but the transfer of the gene from the parent to the offspring. It is also adopted by the unicellular organisms like the bacteria which uses transformation, transduction and conjugation for the horizontal or lateral transfer of the DNA. It does not create a new allele in a population as no variation or evolution exists in this method. Thus the correct answer for this question is Option A) Horizontal (gene) transfer which is not a potential source of new alleles in a population.

2. This question is easy to solve if we know the concept of genetic drift. Genetic drift causes random effect on the populations. Although it could happen in populations of any sizes it is very stronger in the small sized population. The reason is because there will not be many alleles in a small sized population. Hence we now know that the third option matches perfectly with the concept of genetic drift. But let us also try to understand why the other options are incorrect incase of genetic drift. The genetic drift is an evolutionary concept and hence it does not require selection of adaptations to occur. As said earlier it is a random effect and the first option is invalid for genetic drift but valid for natural selection. The second option which states isolated populations becoming similar over time is actually relevant to the concept of speciation and not genetic drift. We are aware that the genetic drift occurs more rapidly in small sized population and not has greater effects with larger population. The last option is also incorrect because genetic drift does not result from the exchange of genetic material between population but it is the gene flow that occurs. Thus, the correct answer for this question is Option C) It has greatest effect in small populations is true for genetic drift.