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AP®BiologyCollege BoardExam QuestionsUnit 4: Cell Communication & Cell CycleCell Cycle

Cell Cycle (College Board AP® Biology)

Exam Questions

5 mins5 questions
1
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During wound healing in human skin, fibroblast cells rapidly divide to help repair damaged tissue. The regulation of this healing process is crucial for preventing excessive scarring. Which of the following best describes how cyclins control this process at the molecular level?

  • Cyclins bind to DNA in order to trigger DNA replication to create new cells to repair the damaged tissue

  • Cyclins form complexes with kinases that remove phosphate groups from target proteins

  • Cyclins bind to cyclin-dependent kinases to form complexes that phosphorylate target proteins

  • Cyclins break down target proteins to signal the next phase of the cell cycle

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21 mark

Scientists studying intestinal epithelial cells in mammals observed that these cells typically divide every 10 hours under normal conditions. Figure 1 shows the distribution of time spent in each of the phases of the cell cycle. Which of the following best explains the process occurring during G1 phase of the cell cycle?

Pie chart with three segments labelled G1, G2, and M. Arrows indicate direction. Segment S is marked with dashed lines between G2 and M.
Figure 1. The stages of the cell cycle.

  • Increased protein synthesis to separate sister chromatids during mitosis.

  • Increased protein synthesis to produce enzymes and proteins needed for cell growth.

  • Increased protein synthesis to create new DNA during replication.

  • Increased protein synthesis to form the nuclear envelope after cell division.

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3
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The death rate from malignant brain tumors was investigated in the UK. The graph in Figure 2 shows the results for women in different age groups.

Bar graph showing rising death rates per 50,000 population with age, from 20 to 90 years. The rate peaks at 90 years with highest death rate.
Figure 2. Graph showing the death rate from malignant brain tumours in women at different ages in the UK.

Which of the following conclusions are supported by this data?

  • Rate of brain tumor diagnosis increases with age.

  • Death rate of people with brain tumors is increases with age.

  • Brain tumors do not occur in the under 20's.

  • Brain tumor death rate differs between men and women.

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4
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A researcher studying cell division in onion root tips adds a chemical that prevents the formation of spindle fibers. Predict the affect that this would have on the chromosomes observed in these cells?

  • Chromosomes would fail to align at the metaphase plate

  • DNA would not replicate during S phase

  • Cytokinesis would occur before nuclear division

  • Sister chromatids would fail to separate during prophase

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5
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A cancer researcher studied the effects of a potential chemotherapy drug on cell division in three different cell lines. The table shows the percentage of cells in each phase of the cell cycle after 24 hours of treatment.

Cell type

Percentage of cells at each cell cycle stage (%)

G1

S

G2

M

Control

40

25

20

15

Cancer

15

15

20

45

Treated cancer

65

10

15

5

Which of the following best explains the drug's likely mechanism of action based on the cell cycle distribution data?

  • The drug causes cells to accumulate in G1 phase by preventing entry into S phase.

  • The drug accelerates progression through all phases of the cell cycle.

  • The drug causes cells to skip G1 phase entirely.

  • The drug promotes rapid progression through the G1 phase into the S phase.

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