Genetic Diversity and Natural Diversity Flashcards
Give two ways in which the genetic diversity of a population might increase.
Anatomical adaptations are structural features of an organism’s body that increase its chance of survival. E.g. seals have a thick layer of blubber to keep them warm in cold seas.
Why would natural selection be unable to act on a population of cloned (genetically identical) individuals?
Natural selection requires genetic variation to cause differential reproductive success in a population. In a genetically identical population, there is no genetic variation and therefore natural selection can’t happen.
Suggest why a mutation that provides increased resistance to an antibiotic might not become more common in a population of bacteria.
E.g. if a bacterial population with a mutation that gives resistance to an antibiotic is not exposed to the antibiotic, the mutation is not likely to become more common. This is because those with the mutation will not have any selective advantage over those that don’t have it.
The Afrikaner population of South Africa is mainly descended from just a few original Dutch settlers. It has been found that this population has an unusually high number of cases of Huntington’s disease, which is caused by an inherited harmful allele of the huntingtin gene.
Suggest why Huntington’s disease is unusually prevalent in the Afrikaners population.
E.g. one of the original settlers carried the harmful allele for the huntingtin gene.
As there were only a few settlers, the initial gene pool for the Afrikaner population was quite small and so the frequency of the harmful allele was much higher than it was in the original Dutch population.
This led to the increased prevalence of Huntington’s disease in the Afrikaner population compared to elsewhere. It’s an example of the founder effect.
Around 10 000 years ago, a mutation in the gene that codes for the lactase enzyme gave some people the ability to digest the lactose in milk as adults. What type of adaptation is this?
The ability of adults to digest lactose is a physiological adaptation an adaptation to a process that goes on - inside an organism’s body (in this case, a reaction involved in digestion).
Suggest how the mutation in the lactase gene became more common in the populations that carried it.
E.g. the mutation became more common through natural selection. The mutation was beneficial as it allowed adults to use milk as a food source. Therefore, those with the mutation would have been more likely to survive and pass on the beneficial allele to the next generation. This means that a greater proportion of the next generation would have inherited the beneficial allele, increasing its frequency over subsequent generations.
