Question 1

Which phase of the cell cycle is primarily responsible for the duplication of chromosomes, and what would be the consequence if this phase was skipped?

Accepted Answer

S phase; daughter cells would not receive the correct amount of genetic material.

Question 2

During which phase of mitosis do the chromosomes align at the metaphase plate, and what is the significance of this alignment?

Accepted Answer

Metaphase; it ensures that each daughter cell receives an identical set of chromosomes.

Question 3

What is the role of the kinetochore during mitosis?

Accepted Answer

It attaches spindle microtubules to the centromere of each chromosome.

Question 4

A mutation in the p53 gene is found in a patient's tumor biopsy. What is the most likely consequence of this mutation?

Accepted Answer

Damaged DNA will not be repaired, increasing the risk of cancer.

Question 5

Which of the following best describes the difference between cytokinesis in animal and plant cells?

Accepted Answer

Animal cells use a contractile ring of actin filaments, while plant cells build a new cell wall from vesicles.

Question 6

Which checkpoint in the cell cycle ensures that all chromosomes are properly attached to the spindle before anaphase begins?

Accepted Answer

Spindle (M) checkpoint

Question 7

What is the function of cyclin-dependent kinases (Cdks) in the cell cycle?

Accepted Answer

They phosphorylate target proteins to regulate cell cycle progression.

Question 8

A scientist observes that cells in a tissue culture stop dividing when they become crowded. Which phenomenon is being observed?

Accepted Answer

Density-dependent inhibition

Question 9

Which of the following equations correctly represents the number of chromosomes ($$n) $$and chromatids ($$c) in a $$human somatic cell during metaphase of mitosis?

Accepted Answer

$$n = 46, c = 92$$

Question 10

Which event marks the transition from metaphase to anaphase during mitosis?

Accepted Answer

Separation of sister chromatids at the centromere

Question 11

A researcher adds platelet-derived growth factor (PDGF) to a culture of fibroblasts. What is the expected outcome?

Accepted Answer

Cells will begin to divide, even if they were previously in G0.

Question 12

Which of the following statements about binary fission in bacteria is correct?

Accepted Answer

It results in two genetically identical daughter cells.

Question 13

If a proto-oncogene is mutated into an oncogene, what is the most likely result?

Accepted Answer

The cell may begin to divide uncontrollably, potentially leading to cancer.

Question 14

Which protein complex is responsible for removing cohesin and allowing sister chromatids to separate during anaphase?

Accepted Answer

Anaphase-Promoting Complex (APC)

Question 15

A cell is observed with chromosomes clustered at opposite poles, nuclear envelopes reforming, and chromosomes decondensing. Which phase is this?

Accepted Answer

Telophase

Question 16

Which of the following best explains why cancer cells can divide indefinitely?

Accepted Answer

They have lost normal cell cycle controls, such as those regulated by tumor-suppressor genes.

Question 17

What would happen if the spindle checkpoint failed and a cell entered anaphase with unattached chromosomes?

Accepted Answer

Daughter cells could receive an abnormal number of chromosomes (aneuploidy).

Question 18

Which of the following is a direct result of the activation of G1/S Cdk at the G1/S checkpoint?

Accepted Answer

Initiation of DNA replication

Question 19

A cell is unable to attach to a substratum and fails to divide. Which regulatory mechanism is responsible for this observation?

Accepted Answer

Anchorage dependence

Question 20

Which of the following best describes the role of cohesin proteins during mitosis?

Accepted Answer

They hold sister chromatids together until anaphase.

The Cell Cycle and Mitosis: Structure, Regulation, and Cancer

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