The 2019 AP Biology Free Response Questions (FRQs) were designed to assess students’ understanding of key biological concepts and their ability to apply these concepts to real-world scenarios. The FRQs covered a wide range of topics, including ecology, evolution, molecular biology, and physiology.
FRQ 1: Population Ecology
Question:
A population of squirrels is being studied in a forest. The following data was collected:
- Population size: 100 squirrels
- Carrying capacity: 200 squirrels
- Birth rate: 0.5 squirrels/month
- Death rate: 0.2 squirrels/month
Part A:
Calculate the population growth rate (r) of the squirrel population.
Solution:
The population growth rate is calculated using the following formula:
r = (Birth rate - Death rate) * Population size / Carrying capacity
r = (0.5 - 0.2) * 100 / 200
r = 0.15 squirrels/month
Part B:
Predict what will happen to the population size over time if the carrying capacity remains constant.
Solution:
The population will continue to grow until it reaches its carrying capacity. Once the carrying capacity is reached, the population will stabilize and remain constant.
FRQ 2: Evolution
Question:
A group of scientists is studying the evolution of beak size in a population of finches. They measure the beak size of 100 finches and find that the average beak size is 10 mm. The scientists then expose the finches to a new environment where the food is harder to reach.
Part A:
Explain how natural selection could lead to an increase in beak size in the finch population.
Solution:
Natural selection could lead to an increase in beak size in the finch population because finches with larger beaks would be able to access the food more easily. This would give them an advantage over finches with smaller beaks, and they would be more likely to survive and reproduce. Over time, this would lead to an increase in the average beak size of the finch population.
Part B:
Predict how the beak size of the finch population would change over time if the new environment remained constant.
Solution:
If the new environment remained constant, the beak size of the finch population would continue to increase until it reached an optimal size for accessing the food. Once the optimal size was reached, the beak size would stabilize and remain constant.
FRQ 3: Molecular Biology
Question:
A researcher is studying the expression of a gene in a human cell. The researcher isolates the gene and inserts it into a plasmid. The plasmid is then inserted into a bacterial cell, and the expression of the gene is monitored.
Part A:
Explain how the researcher can use this technique to determine if the gene is regulated by a transcription factor.
Solution:
The researcher can use this technique to determine if the gene is regulated by a transcription factor by mutating the binding site for the transcription factor in the plasmid. If the expression of the gene changes when the binding site is mutated, then it is likely that the gene is regulated by the transcription factor.
Part B:
Predict what would happen to the expression of the gene if the researcher added a strong promoter to the plasmid.
Solution:
If the researcher added a strong promoter to the plasmid, the expression of the gene would increase. This is because a strong promoter would recruit more RNA polymerase to the gene, which would lead to more transcription of the gene.
FRQ 4: Physiology
Question:
A patient is experiencing shortness of breath and fatigue. The patient’s blood is analyzed and the following results are obtained:
- Blood pH: 7.2
- Blood bicarbonate concentration: 20 mM
- Blood oxygen saturation: 90%
Part A:
Diagnose the patient’s condition based on the blood test results.
Solution:
The patient is experiencing respiratory acidosis. This is because the blood pH is below 7.35, the blood bicarbonate concentration is below 24 mM, and the blood oxygen saturation is below 95%.
Part B:
Explain how the patient’s condition could lead to tissue damage.
Solution:
The patient’s condition could lead to tissue damage because the acidosis will cause the cells to release hydrogen ions. These hydrogen ions will damage the cells and tissues, and can lead to organ failure if the acidosis is not treated.
Conclusion
The 2019 AP Biology FRQs were a challenging but fair assessment of students’ understanding of key biological concepts. The FRQs covered a wide range of topics, and students who were well-prepared were able to demonstrate their knowledge and skills.
