Which one of the following can create new alleles?
a. sexual recombination
b. natural selection
d. mutation
The correct answer and explanation is :
The correct answer is d. mutation.
Explanation:
Mutation is the process that creates new alleles in a population. A mutation refers to a change in the DNA sequence of an organism’s genome. These changes can occur due to various factors, such as errors during DNA replication, exposure to certain chemicals or radiation, or biological processes like transposons. Mutations can affect a single nucleotide (point mutation), large sections of chromosomes (insertions or deletions), or even entire genes (gene duplications). Importantly, mutations can alter the genetic code in such a way that new alleles—variations of a gene—are formed. These new alleles can then be passed on to subsequent generations if they occur in the gametes (sperm or eggs) of the organism.
Mutations can have a variety of effects:
- Neutral mutations: These do not affect the fitness of an organism.
- Beneficial mutations: These improve an organism’s fitness in its environment.
- Harmful mutations: These decrease an organism’s fitness.
However, sexual recombination (a) and natural selection (b) do not directly create new alleles:
- Sexual recombination is the process by which genetic material is shuffled during the formation of gametes (sperm and eggs) in sexually reproducing organisms. This process mixes alleles from both parents, creating new combinations of alleles but does not create entirely new alleles. It increases genetic diversity by redistributing existing alleles.
- Natural selection is a process that influences the frequency of existing alleles in a population based on their effects on survival and reproduction. It does not create new alleles but instead selects for or against alleles that are already present in the population. Over time, natural selection can lead to changes in allele frequencies, which may result in evolutionary changes in a population.
Thus, only mutation directly creates new alleles, while sexual recombination and natural selection work on the genetic variation that is already present.