Question 1

Which of the following is NOT a way in which a proto-oncogene can become an oncogene?

Accepted Answer

Loss of heterozygosity in a tumor suppressor gene

Question 2

What is the normal role of proto-oncogenes in the cell?

Accepted Answer

They encode proteins that stimulate cell growth and division under controlled conditions

Question 3

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

Accepted Answer

It causes the Ras protein to be constantly active, leading to uncontrolled cell division

Question 4

How does a mutation in the p53 gene contribute to cancer development?

Accepted Answer

It prevents the cell from repairing damaged DNA or undergoing apoptosis, allowing mutations to accumulate

Question 5

Which of the following best describes the multistep model of cancer development?

Accepted Answer

Multiple genetic changes accumulate over time, affecting both proto-oncogenes and tumor suppressor genes

Question 6

How can a virus cause cancer in a host organism?

Accepted Answer

By inserting its genetic material into the host genome, disrupting normal regulation of cell division

Question 7

Which equation best represents the relationship between the number of mutations ($$n) $$required for cancer and the probability ($$P) of $$cancer development, assuming each mutation is independent and has a probability $$p of $$occurring?

Accepted Answer

$$P = 1 - (1 - p)^n$$

Question 8

A patient is found to have a translocation that places a proto-oncogene next to a highly active promoter. What is the most likely consequence?

Accepted Answer

Uncontrolled cell division due to overexpression of the proto-oncogene

Question 9

Which of the following scenarios best illustrates the role of tumor suppressor genes?

Accepted Answer

A cell with a mutated tumor suppressor gene fails to undergo apoptosis after DNA damage

Question 10

Which of the following is a common misconception about the development of cancer?

Accepted Answer

Cancer can result from a single genetic mutation

Question 11

A patient’s tumor cells show a loss of function in the p53 gene. Which process is most likely impaired?

Accepted Answer

Cell cycle arrest in response to DNA damage

Question 12

Which of the following is a direct effect of a point mutation in a proto-oncogene?

Accepted Answer

Production of a hyperactive protein that stimulates cell division

Question 13

If a virus integrates into the host genome near a proto-oncogene, what is a possible outcome?

Accepted Answer

Activation of the proto-oncogene, leading to increased cell proliferation

Question 14

Which of the following best explains why cancer is considered a multistep process?

Accepted Answer

It requires the accumulation of several mutations in key regulatory genes over time

Question 15

A cell acquires a mutation that causes the Ras protein to remain bound to GTP. What is the most likely cellular outcome?

Accepted Answer

Continuous stimulation of cell division

Question 16

Which of the following is a function of the p53 protein in normal cells?

Accepted Answer

Inducing cell cycle arrest in response to DNA damage

Question 17

Which of the following genetic changes is most likely to convert a proto-oncogene into an oncogene?

Accepted Answer

A point mutation that increases protein activity

Question 18

Which of the following best describes the role of tumor suppressor genes in cancer prevention?

Accepted Answer

They encode proteins that inhibit cell division and promote apoptosis

Question 19

A patient is diagnosed with a cancer caused by a virus. Which mechanism is most likely responsible?

Accepted Answer

The virus inserted its DNA near a proto-oncogene, causing its overexpression

Question 20

Which of the following is a key step in the multistep model of cancer development?

Accepted Answer

Accumulation of mutations in both proto-oncogenes and tumor suppressor genes

Cancer: Genetic and Molecular Mechanisms

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