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 similar but not identical, each inherited from a different parent, while 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 chromosomes composed of two sister chromatids.

Question 3

Refer to 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 ensures that DNA is undamaged and the cell is ready for DNA replication?

Accepted Answer

G1/S checkpoint

Question 5

A mutation in the p53 gene can lead to cancer because:

Accepted Answer

It prevents cells from undergoing apoptosis when DNA is damaged.

Question 6

How many copies of a tumor suppressor gene must be mutated to contribute to cancer development?

Accepted Answer

Both copies

Question 7

What is the role of Ras in the cell cycle, and what happens if Ras is constitutively active due to mutation?

Accepted Answer

Ras stimulates cell division; a constitutively active Ras leads to uncontrolled cell division.

Question 8

Which of the following best describes the function of microtubules during mitosis?

Accepted Answer

Microtubules form the spindle apparatus that separates sister chromatids during anaphase.

Question 9

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

Accepted Answer

Cytokinesis

Question 10

Doxorubicin is a chemotherapy drug that inhibits DNA synthesis. Which phase of the cell cycle is most affected by this drug?

Accepted Answer

S phase

Question 11

Tamoxifen is used to treat breast cancer by inhibiting estrogen receptor activity. Why does Tamoxifen increase bone density in patients, despite inhibiting estrogen signaling in breast cells?

Accepted Answer

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

Question 12

Which of the following is a plausible outcome if a cell fails the G2/M checkpoint?

Accepted Answer

The cell enters mitosis with damaged DNA, increasing the risk of cancer.

Question 13

Which of the following best describes the effect of a mutation in a proto-oncogene?

Accepted Answer

It results in gain of function, leading to uncontrolled cell division.

Question 14

If a cell has four chromosomes in G1, how many DNA molecules and chromosomes will it have after S phase?

Accepted Answer

Four chromosomes and eight DNA molecules.

Question 15

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

Accepted Answer

Chemicals can cause mutations in DNA, leading to loss of function in tumor suppressor genes and uncontrolled cell division.

Question 16

Which of the following equations correctly represents the DNA content after DNA replication in a diploid cell with $$n$$ chromosomes?

Accepted Answer

$$2n$$ chromosomes, $$4n$$ DNA molecules

Question 17

Which of the following best explains why only one mutated copy of a proto-oncogene can lead to cancer?

Accepted Answer

Proto-oncogenes are dominant; a single mutated copy can activate cell division.

Question 18

Which of the following is NOT a function of the p53 protein?

Accepted Answer

Promoting cell cycle progression

Question 19

A patient’s tumor cells do not respond to radiation therapy and continue dividing. Which gene is most likely mutated?

Accepted Answer

p53

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

Guida di studio - Domande di pratica

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