A Level Biology Practice Exam

What is genetic variation primarily characterized by?

1. Differences in phenotypes within a population

2. A variety of different combinations of alleles in a population

3. Uniform allele combinations across individuals

4. Stable genetic traits across generations

The correct answer is: A variety of different combinations of alleles in a population

Genetic variation is primarily characterized by a variety of different combinations of alleles within a population. This diversity in allele combinations arises from several mechanisms such as mutation, recombination during sexual reproduction, and gene flow between populations. Each individual inherits a unique set of alleles from its parents, which contributes to the genetic makeup of the population and influences traits and characteristics. While differences in phenotypes within a population can reflect underlying genetic variation, they are not the primary defining feature of genetic variation itself. Uniform allele combinations across individuals and stable genetic traits across generations indicate low genetic variation, as they suggest that there is little to no diversity in the genetic information present in the population. Thus, the presence of varied combinations of alleles is what fundamentally characterizes genetic variation, providing the raw material for evolution and adaptation.