Question 1

Which of the following best describes what happens during metaphase of mitosis?

Accepted Answer

Chromosomes align at the metaphase plate, with kinetochores attached to spindle microtubules.

Question 2

A researcher adds colchicine to a culture of dividing cells. Colchicine blocks the formation of the mitotic spindle. What is the most likely result?

Accepted Answer

Chromosomes would condense, but fail to align at the metaphase plate, and the cell cycle would stop.

Question 3

Which checkpoint is considered the most important for determining whether a cell will complete the cell cycle?

Accepted Answer

G1 checkpoint

Question 4

What is the role of the enzyme separase during mitosis?

Accepted Answer

It cleaves cohesin proteins, allowing sister chromatids to separate during anaphase.

Question 5

Which of the following is a property of cancer cells that distinguishes them from normal cells?

Accepted Answer

They do not respond to signals that normally regulate the cell cycle.

Question 6

A mutation in a proto-oncogene can lead to cancer because:

Accepted Answer

It results in the cell cycle being constantly signaled to grow.

Question 7

Which of the following best describes the function of the mitotic spindle?

Accepted Answer

It controls chromosome movement during mitosis.

Question 8

If a cell fails to receive a 'go-ahead' signal at the G1 checkpoint, what is the most likely outcome?

Accepted Answer

The cell will enter the G0 phase and stop dividing.

Question 9

Which of the following equations correctly represents the relationship between the number of chromosomes ($n$) and the number of chromatids during metaphase in a human cell?

Accepted Answer

$2n$ chromosomes and $4n$ chromatids$

Question 10

Which of the following best explains why platelet-derived growth factor (PDGF) is important in wound healing?

Accepted Answer

PDGF stimulates fibroblasts to divide and repair tissue.

Question 11

A cell is observed with chromosomes aligned at the metaphase plate, but anaphase does not begin. Which checkpoint is most likely preventing progression?

Accepted Answer

M checkpoint (spindle checkpoint)

Question 12

Which of the following statements about tumor-suppressor genes is correct?

Accepted Answer

They prevent the development of cells containing mutations.

Question 13

During which phase of mitosis does the nuclear envelope begin to reform and chromosomes start to uncoil?

Accepted Answer

Telophase

Question 14

Which of the following best describes density-dependent inhibition?

Accepted Answer

Cells stop dividing when they become too crowded.

Question 15

A scientist fuses a cell in S phase with a cell in G1 phase. What is the most likely outcome for the G1 nucleus?

Accepted Answer

It immediately enters S phase and DNA is synthesized.

Question 16

Which of the following is NOT a characteristic of cancer cells?

Accepted Answer

They exhibit anchorage dependence.

Question 17

Which of the following events marks the transition from metaphase to anaphase?

Accepted Answer

Cleavage of cohesin proteins by separase

Question 18

If a cell's p53 gene is mutated and nonfunctional, what is a likely consequence?

Accepted Answer

The cell may continue to divide even with damaged DNA, increasing cancer risk.

Question 19

Which of the following best describes the difference between benign and malignant tumors?

Accepted Answer

Benign tumors remain at the original site, while malignant tumors invade tissues and may metastasize.

Question 20

Which of the following best explains why cells in G0 phase do not divide?

Accepted Answer

They did not receive a 'go-ahead' signal at the G1 checkpoint.

Mitosis and Cell Cycle Control: Structure, Regulation, and Loss of Control

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