Genetic diversity and adaptation: Practice Questions

The diagram shows the distribution of phenotypes in a population before and after a period of natural selection. Which type of selection is illustrated by the change in phenotypic frequency?

A scientist is studying a population of bacteria that has developed resistance to a specific antibiotic. This resistance arose from a random mutation that provided a selective advantage in the presence of the drug. Which type of selection is being described?

In a population of birds, a mutation results in a new allele that gives slightly longer beaks. These birds are better able to reach insects inside tree bark. Over many generations, the frequency of this allele increases. Which statement most accurately explains this change?

In a population of humans, babies with a birth weight significantly lower or higher than the mean are less likely to survive. This results in the mean birth weight remaining constant over generations. Which type of selection does this describe?

Human birth weight is often cited as an example of stabilising selection. Which of the following best explains the mechanism behind this type of selection?

In the context of natural selection, explain how an advantageous mutation leads to a change in the allele frequency of a population over many generations.

In a population of bacteria, the frequency of an allele for antibiotic resistance increases rapidly following the introduction of a new drug. Identify the type of selection occurring and explain how differential reproductive success leads to this change in the gene pool.

In a population of Passer domesticus, individuals with larger wingspans are better able to survive severe storms, whereas those with smaller wingspans are less likely to survive. Explain how directional selection, acting over many generations, would affect the allele frequency for large wingspans and suggest the role of random mutation in this evolutionary process.

Genetic diversity within a population is the raw material for natural selection.

a) Explain how gene mutations can lead to the production of non-functional proteins. (2 points)
b) Describe the process of natural selection and how it leads to directional selection in a population subjected to a change in environmental conditions. (3 points)
c) Distinguish between anatomical and physiological adaptations, providing one example of each for a named organism. (2 points)