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 two chromosomes, one from each parent, with the same genes but possibly different alleles; sister chromatids are identical copies formed by DNA replication.

Question 2

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

Accepted Answer

DNA replication occurs during S phase, resulting in a doubling of DNA content.

Question 3

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

Accepted Answer

Interphase; it is responsible for cell growth, DNA replication, and preparation for mitosis.

Question 4

What is the main purpose of the G1 checkpoint in the cell cycle, as shown in the fourth image?

Accepted Answer

To check for DNA damage and ensure the cell is ready for DNA replication.

Question 5

A mutation in the ras gene leads to a Ras protein that is always active. Based on the fifth and sixth images, what is the most likely cellular outcome?

Accepted Answer

The cell will undergo continuous division, even without growth factor signals.

Question 6

Which of the following best explains the role of p53 in the cell cycle, as depicted in the seventh and eighth images?

Accepted Answer

p53 inhibits the cell cycle when DNA damage is detected, allowing for repair or apoptosis.

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 be able to inhibit the cell cycle in response to DNA damage, increasing the risk of cancer.

Question 8

Which of the following best describes how Herceptin works as a therapy for HER2-positive breast cancer, as shown in the last two images?

Accepted Answer

Herceptin binds to the HER2 receptor, blocking its activity and preventing cell division.

Question 9

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

Accepted Answer

Proto-oncogenes promote cell division and can become oncogenes when mutated; tumor suppressor genes inhibit cell division and require both copies to be mutated to lose function.

Question 10

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

Accepted Answer

Metaphase, because chromosomes cannot align at the metaphase plate without spindle fibers.

Question 11

Which of the following equations correctly represents the change in DNA content during the S phase of the cell cycle?

Accepted Answer

$$DNA_{after\ S} = 2 	imes DNA_{before\ S}$$

Question 12

A patient is treated with a drug that disrupts actin filaments. Which process in cell division would be most directly inhibited?

Accepted Answer

Cytokinesis, because actin forms the contractile ring that divides the cytoplasm.

Question 13

If a cell fails the G2/M checkpoint, what is the most likely reason?

Accepted Answer

The cell has not completed DNA replication or has DNA damage.

Question 14

Which of the following best explains why only one mutated copy of a proto-oncogene is sufficient to contribute to cancer development?

Accepted Answer

Proto-oncogenes are dominant; a single mutated allele can promote uncontrolled cell division.

Question 15

A cell with a defective p53 gene is exposed to UV light. What is the most likely outcome?

Accepted Answer

The cell will not inhibit the cell cycle, leading to increased risk of cancer.

Question 16

Which of the following best describes the role of kinetochores during mitosis?

Accepted Answer

Kinetochores attach chromosomes to spindle fibers, allowing for their movement during mitosis.

Question 17

Which of the following is a real-world example of how environmental chemicals can lead to cancer?

Accepted Answer

Chemicals can cause mutations in DNA, leading to the activation of oncogenes or inactivation of tumor suppressor genes.

Question 18

A patient with breast cancer is found to be ER/PR positive and HER2 negative. Which therapy is most likely to be effective?

Accepted Answer

Tamoxifen, because it inhibits estrogen receptor signaling.

Question 19

Which of the following best explains why doxorubicin is most toxic during the S phase of the cell cycle?

Accepted Answer

Doxorubicin inhibits DNA synthesis, which occurs during S phase.

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

Guida di studio - Domande di pratica

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