AP Biology natural selection review questions and answers

📚 Quick Study Guide

• 🌱 Definition: Natural selection is the process where organisms with traits that enable them to survive and reproduce in an environment tend to leave more offspring than individuals without those traits.
• 🧬 Key Principles:
  • 🌍 Variation exists within populations.
  • 🕰️ Variations are heritable.
  • 📈 Organisms produce more offspring than can survive.
  • 🎯 Individuals with advantageous traits survive and reproduce more successfully.
• ⚖️ Fitness: A measure of an organism's ability to survive and reproduce, often quantified by the number of offspring it produces.
• 🧪 Mechanisms:
  • 🛡️ Directional Selection: Favors one extreme phenotype.
  • 📈 Stabilizing Selection: Favors intermediate phenotypes.
  • 💥 Disruptive Selection: Favors both extreme phenotypes.
• 📝 Hardy-Weinberg Equilibrium: Describes a population that is not evolving. The conditions for equilibrium are:
  • ➕ No mutation
  • ➖ Random mating
  • ➗ No gene flow
  • ✖️ No natural selection
  • 💯 Extremely large population size
  The equations are: $p + q = 1$ and $p^2 + 2pq + q^2 = 1$, where $p$ is the frequency of the dominant allele and $q$ is the frequency of the recessive allele.

Practice Quiz

1. Which of the following is NOT a condition required for natural selection to occur?
   1. Variation in traits
   2. Heritability of traits
   3. Unlimited resources
   4. Differential reproductive success
2. Directional selection favors which type of phenotype?
   1. Intermediate
   2. Both extremes
   3. One extreme
   4. A mix of all phenotypes
3. What does fitness measure in the context of natural selection?
   1. Physical strength
   2. Ability to avoid predators
   3. Reproductive success
   4. Lifespan
4. In a population of birds, larger beaks are selected for during a drought because they can crack larger seeds. This is an example of:
   1. Stabilizing selection
   2. Disruptive selection
   3. Directional selection
   4. Genetic drift
5. Which of the following can disrupt Hardy-Weinberg equilibrium?
   1. Random mating
   2. Large population size
   3. No gene flow
   4. Natural selection
6. A population of butterflies has two color forms: blue and yellow. Over time, the environment changes, and both blue and yellow butterflies become more common than green butterflies. This is an example of:
   1. Directional selection
   2. Stabilizing selection
   3. Disruptive selection
   4. Sexual selection
7. What is the role of variation in natural selection?
   1. It prevents adaptation.
   2. It provides the raw material for selection.
   3. It ensures all individuals are equally fit.
   4. It maintains genetic equilibrium.