AP Biology FRQ Practice

1. Cell Biology: Structure and Function

Question:

The process of protein synthesis involves multiple stages: transcription, translation, and post-translational modifications.

(a) Describe the role of RNA polymerase in transcription.

(b) Explain the process of translation and the role of ribosomes.

(c) Discuss the significance of post-translational modifications in protein function.

Response Guidelines:

• Part (a):
  RNA polymerase is responsible for synthesizing messenger RNA (mRNA) during transcription. It binds to the promoter region of DNA and moves along the template strand, synthesizing a complementary RNA strand.
• Part (b):
  Translation occurs in the cytoplasm, where ribosomes read the mRNA and use it to assemble a chain of amino acids into a polypeptide. The ribosome facilitates the binding of tRNA molecules, each carrying an amino acid, to the mRNA codons.
• Part (c):
  Post-translational modifications, such as phosphorylation, glycosylation, and cleavage, modify the protein structure and function. These modifications can alter the protein’s activity, localization, or stability, playing a key role in regulating cellular processes.

2. Genetics and Evolution

Question:

In pea plants, the allele for tall (T) is dominant over the allele for short (t). A heterozygous tall plant (Tt) is crossed with a short plant (tt).

(a) What is the genotype of the offspring in this cross?

(b) What is the expected phenotypic ratio of the offspring?

(c) Explain how this inheritance pattern is an example of Mendelian genetics.

Response Guidelines:

• Part (a):
  The possible genotypes of the offspring are Tt (tall) and tt (short). The cross will result in 50% tall plants (Tt) and 50% short plants (tt).
• Part (b):
  The expected phenotypic ratio is 1 tall: 1 short. Since the T allele is dominant, any offspring with the T allele will display the tall phenotype.
• Part (c):
  This inheritance pattern follows Mendel’s Law of Segregation, where each parent contributes one allele for a trait, and offspring inherit one allele from each parent. This results in a predictable pattern of inheritance.

3. Ecology

Question:

Consider a population of deer in a forest ecosystem. The population is experiencing logistic growth and is regulated by the availability of food, predation, and disease.

(a) Explain the concept of carrying capacity and how it affects the population growth of deer.

(b) Describe two density-dependent factors and two density-independent factors that influence the deer population.

(c) Graph the population growth curve of the deer population, indicating the phases of growth and carrying capacity.

Response Guidelines:

• Part (a):
  Carrying capacity refers to the maximum population size that an environment can support based on the available resources. When the population reaches the carrying capacity, growth slows, and the population stabilizes.
• Part (b):
  Density-dependent factors include food availability and predation. These factors become more influential as the population density increases. Density-independent factors include weather conditions and natural disasters, which can affect the population regardless of its size.
• Part (c):
  The population growth curve typically has an S-shape, known as logistic growth. It starts with a slow increase (lag phase), followed by a rapid growth phase (exponential growth), and eventually levels off at the carrying capacity, forming the stationary phase.

Grading Rubric for AP Biology FRQs

1. Cell Biology: Structure and Function

• Part (a):
  • 0-1 points: Incorrect or incomplete description of RNA polymerase.
  • 2 points: Correctly describes the role of RNA polymerase in transcription.
• Part (b):
  • 0-1 points: Incorrect or incomplete explanation of translation and ribosome function.
  • 2 points: Correctly explains translation and the role of ribosomes.
• Part (c):
  • 0-1 points: Incorrect or incomplete discussion of post-translational modifications.
  • 2 points: Correctly discusses the significance of post-translational modifications in protein function.

2. Genetics and Evolution

• Part (a):
  • 0-1 points: Incorrect or incomplete genotype prediction.
  • 2 points: Correctly predicts the genotype of the offspring.
• Part (b):
  • 0-1 points: Incorrect or incomplete phenotypic ratio.
  • 2 points: Correctly predicts the phenotypic ratio of the offspring.
• Part (c):
  • 0-1 points: Incorrect or incomplete explanation of Mendelian genetics.
  • 2 points: Correctly explains the inheritance pattern as an example of Mendelian genetics.

3. Ecology

• Part (a):
  • 0-1 points: Incorrect or incomplete explanation of carrying capacity.
  • 2 points: Correctly explains the concept of carrying capacity and its effect on population growth.
• Part (b):
  • 0-1 points: Incorrect or incomplete description of density-dependent and density-independent factors.
  • 2 points: Correctly describes two density-dependent and two density-independent factors.
• Part (c):
  • 0-1 points: Incorrect or incomplete graph of population growth.
  • 2 points: Correctly graphs the population growth curve with phases and carrying capacity.

Sample Grading Breakdown (for one FRQ)

• Cell Biology: 6 points
• Genetics and Evolution: 6 points
• Ecology: 6 points
• Total: 18 points (for all three FRQs combined)