AP Biology Sample Past Paper 2023 — Section I Multiple Choice
Many students panic during AP Biology's Section I because they misjudge which facts matter most and run out of time on harder conceptual questions. This sample paper drills the fastest, highest-yield concepts: molecular structure and energy flow, cell division and genetic inheritance, and real-world ecology scenarios that test synthesis over memory. You'll find 15 questions (multiple-choice, true/false, and fill-in-the-blank) that mirror the style and difficulty of the College Board exam, covering chemistry of life, cellular energetics, heredity, and ecological relationships. Designed for Grade 12 AP Biology students in their final exam preparation. By the end, you'll confidently spot the correct answer in 45–60 seconds per question, know which distractors trap the most students, and be ready for test day.
Questions in this quiz
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- Question 1
Water's high specific heat capacity makes it an excellent buffer against temperature change. Which of the following properties of water is primarily responsible for this characteristic?
- Question 2
A researcher measures the ATP concentration in a cell before and after treatment with an inhibitor that blocks the electron transport chain. Which outcome would you predict?
- Question 3
The enzyme lactase breaks down the disaccharide lactose into glucose and galactose. In humans, lactase production typically decreases after early childhood. This is an example of:
- Question 4
True or False: During meiosis I, homologous chromosomes separate, and the result is two daughter cells, each with the haploid number of chromosomes but with each chromosome still composed of two sister chromatids.
- Question 5
A pea plant heterozygous for seed color (Yy) is self-fertilized. If seed color exhibits simple Mendelian dominance (yellow dominant to green), what proportion of offspring will display the recessive phenotype?
- Question 6
During the S phase of the cell cycle, DNA replication occurs. Which of the following best describes why DNA replication must be precise?
- Question 7
A population of bacteria exhibits resistance to a common antibiotic. The most likely explanation for the rapid spread of antibiotic resistance in this population is:
- Question 8
In a stable ecosystem, the total energy fixed by primary producers is approximately 1,000 kcal/m²/year. If secondary consumers (herbivores) assimilate only 10% of the energy consumed, approximately how much energy (in kcal/m²/year) will be available to tertiary consumers (carnivores that eat herbivores)?
- Question 9
A population of moths in an industrial region has shifted from mostly light-colored to mostly dark-colored over several generations. Which of the following best explains this change?
- Question 10
A cell is treated with a drug that disrupts the formation of the spindle fibers during mitosis. Which phase of the cell cycle would be most severely affected?
- Question 11
True or False: In aerobic respiration, the breakdown of glucose yields the same amount of ATP whether oxygen is abundant or scarce, as long as the Krebs cycle completes.
- Question 12
A human inherits one allele for cystic fibrosis (a recessive disorder) from each parent. Which of the following statements is correct?
- Question 13
In an aquatic ecosystem, nutrient cycling is essential for productivity. Which process is responsible for returning nitrogen from dead organisms and waste back to the soil and water?
- Question 14
A researcher observes that in a predator-prey population system, the predator population peaks approximately one generation after the prey population peaks. This time lag is best explained by:
- Question 15
During transcription, the DNA template strand (reading 3' to 5') is used to synthesize mRNA (written 5' to 3'). If the DNA template strand has the sequence 3'-TACGC-5', what is the sequence of the mRNA produced?