Question 1

Which of the following best describes the difference between homologous chromosomes and sister chromatids, as shown in the first image?

Accepted Answer

Homologous chromosomes are inherited from each parent, while sister chromatids are the result of DNA replication.

Question 2

During which phase of the cell cycle does DNA replication occur, and what is the result for chromosome structure?

Accepted Answer

DNA replication occurs during S phase, resulting in chromosomes composed of two sister chromatids.

Question 3

Refer to the cell cycle diagram (third image). Which phase is the longest, and what is its primary function?

Accepted Answer

Interphase; cell growth and DNA replication

Question 4

Which checkpoint in the cell cycle (fourth image) is primarily responsible for ensuring that DNA is undamaged before replication?

Accepted Answer

G1 checkpoint

Question 5

A mutation in the ras gene leads to a protein that is always active (see images 5 and 6). What is the most likely cellular outcome?

Accepted Answer

The cell will continuously divide, even without growth signals.

Question 6

What is the role of the p53 protein in the cell cycle, as illustrated in images 7 and 8?

Accepted Answer

p53 inhibits the cell cycle if DNA damage is detected.

Question 7

If both copies of the p53 gene are mutated in a cell, what is the most likely consequence?

Accepted Answer

The cell will not inhibit the cell cycle in response to DNA damage, increasing cancer risk.

Question 8

Which of the following best explains how Herceptin works as a therapy for HER2-positive breast cancer (see images 9 and 10)?

Accepted Answer

Herceptin binds to HER2 receptors, preventing their activation and subsequent cell division.

Question 9

Which of the following equations correctly represents the DNA content change during the cell cycle for a diploid cell with 2n chromosomes?

Accepted Answer

$$2n \rightarrow 2n$$ during G1, $$2n \rightarrow 4n$$ during S, $$4n \rightarrow 2n$$ after mitosis

Question 10

A chemotherapy drug inhibits microtubule formation. Which stage of mitosis would be most directly affected?

Accepted Answer

Metaphase

Question 11

Which of the following best describes the function of actin filaments during cell division?

Accepted Answer

They form the contractile ring during cytokinesis.

Question 12

A patient’s tumor cells do not undergo apoptosis after radiation therapy. Which gene is most likely mutated?

Accepted Answer

p53

Question 13

Which of the following is a key difference between proto-oncogenes and tumor suppressor genes?

Accepted Answer

Proto-oncogenes promote cell division when mutated, while tumor suppressor genes fail to inhibit cell division when mutated.

Question 14

Which of the following best explains why only one mutated copy of a proto-oncogene can lead to cancer, but both copies of a tumor suppressor gene must be mutated?

Accepted Answer

Proto-oncogenes are dominant, while tumor suppressor genes are recessive at the cellular level.

Question 15

Which of the following best describes the effect of a non-functional spindle checkpoint during mitosis?

Accepted Answer

Cells may divide with abnormal chromosome numbers (aneuploidy).

Question 16

A drug that disrupts actin filaments would most likely inhibit which process?

Accepted Answer

Cytokinesis

Question 17

Which phase of the cell cycle is most sensitive to drugs that inhibit DNA synthesis, such as doxorubicin?

Accepted Answer

S

Question 18

Which of the following best explains why environmental chemicals can cause cancer?

Accepted Answer

They can cause mutations in DNA that disrupt normal cell cycle regulation.

Question 19

Which of the following equations best represents the relationship between chromosome number and DNA content during metaphase of mitosis for a cell with 4 chromosomes?

Accepted Answer

$$4$$ chromosomes, $$8$$ DNA molecules

Question 20

Which of the following best describes the effect of a mutated ras gene that cannot be inactivated?

Accepted Answer

There will be continuous cell division, and the pathway will be on.

Cell Division, Cancer, and Chemotherapy: Step-by-Step Study Guidance

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