Question 1

Which of the following best describes the relationship between chromatin, chromosomes, and the genome in a eukaryotic cell?

Accepted Answer

Chromosomes are made of chromatin, which is a complex of DNA and protein, and the genome is the complete set of DNA in the cell.

Question 2

During which phase of the cell cycle does DNA replication occur?

Accepted Answer

S phase

Question 3

A cell is observed under a microscope with chromosomes aligned at the center of the cell. Which phase of mitosis is this cell in?

Accepted Answer

Metaphase

Question 4

Which of the following statements about sister chromatids is correct?

Accepted Answer

Sister chromatids are identical copies of a chromosome joined at the centromere.

Question 5

In animal cells, what structure is responsible for the formation of the cleavage furrow during cytokinesis?

Accepted Answer

Contractile ring of actin microfilaments

Question 6

Which checkpoint in the cell cycle is most critical for determining whether a cell will proceed to divide?

Accepted Answer

G1 checkpoint

Question 7

A researcher observes that a cell continues to divide even when it is surrounded by other cells and has DNA damage. Which cell cycle controls are most likely failing?

Accepted Answer

Density-dependent inhibition and DNA damage checkpoints

Question 8

Which of the following best describes the role of cyclin-dependent kinases (Cdks) in the cell cycle?

Accepted Answer

Cdks must bind to cyclins to become active and regulate progression through the cell cycle.

Question 9

Which of the following equations correctly represents the chromosome number in somatic cells versus gametes in humans?

Accepted Answer

$$2n = 46 in $$somatic cells; $$n = 23 in $$gametes

Question 10

Which of the following events distinguishes prophase from prometaphase during mitosis?

Accepted Answer

Chromosomes condense and the mitotic spindle begins to form in prophase; the nuclear envelope fragments in prometaphase.

Question 11

A cell is exposed to a drug that prevents the formation of microtubules. Which process will be directly inhibited?

Accepted Answer

Chromosome movement during mitosis

Question 12

Which of the following best explains why cancer cells can form tumors?

Accepted Answer

They ignore density-dependent inhibition and continue to divide uncontrollably.

Question 13

During which stage of mitosis do sister chromatids separate and move toward opposite poles of the cell?

Accepted Answer

Anaphase

Question 14

Which of the following is a key difference between mitosis in animal cells and plant cells?

Accepted Answer

Animal cells form a cleavage furrow during cytokinesis, while plant cells form a cell plate.

Question 15

Which of the following best describes binary fission in bacteria?

Accepted Answer

The bacterial chromosome replicates, and the cell divides as the plasma membrane pinches inward.

Question 16

A cell is observed to have high levels of MPF (maturation-promoting factor). Which phase of the cell cycle is it most likely entering?

Accepted Answer

M phase

Question 17

Which of the following is a real-world example of external regulation of the cell cycle?

Accepted Answer

Platelet-derived growth factor (PDGF) stimulates fibroblast division during wound healing.

Question 18

If a cell fails to attach all chromosomes to spindle fibers at the metaphase plate, what is the likely consequence?

Accepted Answer

The cell will not proceed to anaphase until all chromosomes are properly attached.

Question 19

Which of the following best explains why chemotherapeutic drugs often cause side effects such as hair loss and nausea?

Accepted Answer

They target all rapidly dividing cells, not just cancer cells.

Question 20

A cell with a defective p53 gene is likely to:

Accepted Answer

Fail to stop the cell cycle in response to DNA damage, increasing cancer risk.

The Cell Cycle: Structure, Function, and Regulation

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