AP Biology questions on Genetic Drift

📚 Quick Study Guide

• 🎲 Definition: Genetic drift refers to random fluctuations in allele frequencies within a population from one generation to the next. These changes are due to chance events, not natural selection.
• 📉 Impact: Drift has a more significant impact on small populations, where random events can drastically alter allele frequencies.
• ➡️ Bottleneck Effect: A sudden reduction in population size due to events like natural disasters can lead to the bottleneck effect. The surviving population may not represent the original allele frequencies.
• founder Founder Effect: When a small group of individuals colonizes a new area, the founding population's allele frequencies may differ from the original population.
• ↔️ Allele Fixation/Loss: Over time, genetic drift can lead to the fixation of one allele (frequency = 1) and the loss of other alleles (frequency = 0).
• ➕ No New Alleles: Genetic drift does not create new alleles; it only changes the frequencies of existing ones.
• ➗ Hardy-Weinberg Violation: Genetic drift violates the Hardy-Weinberg equilibrium, which assumes no changes in allele frequencies due to random chance.

🧪 Practice Quiz

1. Which of the following best describes genetic drift?
   1. A) Changes in allele frequencies due to natural selection.
   2. B) Random changes in allele frequencies in a population.
   3. C) The introduction of new alleles into a population.
   4. D) Gene flow between different populations.
2. The bottleneck effect is an example of genetic drift that:
   1. A) Increases genetic diversity.
   2. B) Occurs when a small group colonizes a new habitat.
   3. C) Results from a drastic reduction in population size.
   4. D) Is caused by non-random mating.
3. The founder effect differs from the bottleneck effect because it:
   1. A) Always increases the population size.
   2. B) Involves the establishment of a new population by a small number of individuals.
   3. C) Results in a loss of genetic diversity.
   4. D) Is driven by natural selection.
4. Which of the following is a likely outcome of genetic drift in a small population?
   1. A) Increased genetic diversity.
   2. B) Fixation of one allele and loss of others.
   3. C) Maintenance of Hardy-Weinberg equilibrium.
   4. D) Increased gene flow.
5. Genetic drift is most likely to have a major effect on evolution when:
   1. A) The population is large and stable.
   2. B) The population is small and isolated.
   3. C) There is strong natural selection.
   4. D) There is significant gene flow.
6. Which of the following statements about genetic drift is FALSE?
   1. A) It can lead to the loss of alleles from a population.
   2. B) It is more pronounced in small populations.
   3. C) It always increases the fitness of a population.
   4. D) It is a random process.
7. A population of birds on a remote island exhibits a high frequency of a particular recessive allele. This is most likely due to:
   1. A) Natural selection.
   2. B) Mutation.
   3. C) Genetic drift (founder effect).
   4. D) Gene flow.