Question 1

A patient with invasive ductal carcinoma has a tumor with a Ki-67 index of 35%. What does a high Ki-67 index indicate about the tumor cells?

Accepted Answer

The tumor cells have a high rate of cell division.

Question 2

Which phase of the cell cycle is characterized by DNA replication?

Accepted Answer

S phase

Question 3

Paclitaxel is a chemotherapy drug that disrupts microtubule function. What is the most direct effect of this disruption during mitosis?

Accepted Answer

Chromosomes cannot align at the metaphase plate.

Question 4

Which of the following best describes the difference between a proto-oncogene and a tumor suppressor gene?

Accepted Answer

Proto-oncogenes promote cell division, while tumor suppressor genes inhibit cell division.

Question 5

If two copies of a tumor suppressor gene must be mutated to cause cancer, what is the probability that a cell with one mutated copy will become cancerous after a second mutation? Assume mutation events are independent and each has a probability $$p.$$

Accepted Answer

$$p$$

Question 6

Herceptin is used to treat HER2+ breast cancer. What is its mechanism of action?

Accepted Answer

It binds to HER2 receptors, inhibiting cell proliferation.

Question 7

During which stage of mitosis do sister chromatids separate and move toward opposite poles?

Accepted Answer

Anaphase

Question 8

A cell is observed to have homologous chromosomes paired together. Which process is most likely occurring?

Accepted Answer

Meiosis I

Question 9

Which checkpoint in the cell cycle ensures that all chromosomes are properly attached to the spindle before proceeding?

Accepted Answer

M checkpoint (spindle checkpoint)

Question 10

A mutation in the ras gene leads to continuous cell division. What type of gene is ras?

Accepted Answer

Proto-oncogene

Question 11

Which of the following best explains why doxorubicin is effective against rapidly dividing cancer cells?

Accepted Answer

It intercalates into DNA, preventing replication and transcription.

Question 12

Which of the following is a direct result of a nonfunctional p53 protein in a cell?

Accepted Answer

Cells fail to undergo apoptosis in response to DNA damage.

Question 13

Which of the following events occurs during crossing over in meiosis?

Accepted Answer

Exchange of genetic material between homologous chromosomes

Question 14

A chemotherapy drug blocks the formation of the mitotic spindle. Which phase of the cell cycle would be most directly affected?

Accepted Answer

M phase

Question 15

Which of the following is true about homologous chromosomes?

Accepted Answer

They carry the same genes but may have different alleles.

Question 16

A patient’s tumor shrinks from 3.2 cm to 1.8 cm after chemotherapy. Which cellular process is most likely responsible for this reduction?

Accepted Answer

Induction of apoptosis

Question 17

Which of the following best describes the role of checkpoints in the cell cycle?

Accepted Answer

They prevent cells with damaged DNA from progressing to the next phase.

Question 18

If a cell receives a signal to divide but has unrepaired DNA damage, which protein is most likely to halt the cell cycle?

Accepted Answer

p53

Question 19

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

Accepted Answer

Cancer cells can divide without external growth signals.

Question 20

A researcher introduces a mutant ras gene into a cell. What is the most likely outcome?

Accepted Answer

The cell will divide uncontrollably.

Cell Division, Cancer Biology, and Chemotherapy: Study Guide

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