Question 1

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

Accepted Answer

Homologous chromosomes are two chromosomes, one from each parent, with similar genes but different alleles; sister chromatids are identical copies formed after DNA replication.

Question 2

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

Accepted Answer

DNA replication occurs during S phase, resulting in each chromosome consisting of two sister chromatids.

Question 3

Referencing the cell cycle diagram, which phase is the longest and what is its primary function?

Accepted Answer

Interphase; cell growth, DNA replication, and preparation for division.

Question 4

Which checkpoint in the cell cycle is responsible for ensuring that DNA is undamaged before replication, and what happens if this checkpoint fails?

Accepted Answer

G1/S checkpoint; cells proceed to DNA replication with damaged DNA, increasing cancer risk.

Question 5

A mutation in the p53 gene is shown in the images. What is the most likely outcome for cells with this mutation?

Accepted Answer

Cells will continue to divide even with DNA damage, increasing cancer risk.

Question 6

Based on the Ras pathway images, what happens if Ras is mutated and cannot be inactivated?

Accepted Answer

Cell division occurs continuously, and the pathway is always on.

Question 7

Which of the following best explains how Herceptin works as a therapeutic for HER2-positive breast cancer, as shown in the images?

Accepted Answer

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

Question 8

If a chemotherapy drug targets microtubules, which stage of cell division is most directly affected?

Accepted Answer

Metaphase, because microtubules form the spindle that aligns chromosomes.

Question 9

A patient receives doxorubicin, which intercalates DNA and inhibits DNA synthesis. During which cell cycle phase is this drug most toxic?

Accepted Answer

S phase

Question 10

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

Accepted Answer

Both copies of a tumor suppressor gene must be mutated to cause cancer, while only one mutated proto-oncogene can drive cancer.

Question 11

Which of the following equations correctly represents the DNA content change during the cell cycle, starting from G1 to G2?

Accepted Answer

DNA content doubles: $$2N \rightarrow 4N$$

Question 12

Which of the following best describes the role of actin filaments in cell division?

Accepted Answer

Actin filaments are responsible for forming the contractile ring during cytokinesis.

Question 13

A cell is exposed to a drug that causes disassembly of actin filaments. What is the most likely effect on cell division?

Accepted Answer

Cytokinesis is inhibited, preventing the cell from splitting into two daughter cells.

Question 14

Which of the following is a real-world consequence of a defective spindle checkpoint during mitosis?

Accepted Answer

Cells may develop aneuploidy, leading to abnormal chromosome numbers.

Question 15

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

Accepted Answer

They cause mutations in DNA, which can disrupt cell cycle regulation and lead to uncontrolled cell growth.

Question 16

Which of the following best describes the effect of a functional p53 protein in response to DNA damage?

Accepted Answer

p53 activates transcription of proteins that inhibit the cell cycle, preventing replication of damaged DNA.

Question 17

Which of the following best describes the outcome of a cell with a mutated p53 gene exposed to UV light?

Accepted Answer

The cell cycle is not inhibited, and damaged DNA is replicated, increasing cancer risk.

Question 18

Which of the following best describes the effect of Tamoxifen on bone density in breast cancer patients?

Accepted Answer

Tamoxifen acts as an estrogen antagonist in breast cells but as an agonist in bone cells, increasing bone density.

Question 19

Which of the following equations represents the chromosome number change during mitosis?

Accepted Answer

Chromosome number remains constant: $$2N \rightarrow 2N$$

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

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