Question 1

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

Accepted Answer

Cdks are enzymes that activate or inactivate other proteins by phosphorylation, regulating cell cycle progression.

Question 2

A scientist observes a cell with condensed chromosomes aligned at the metaphase plate, spindle fibers attached to kinetochores, and no nuclear envelope. Which stage of mitosis is the cell in?

Accepted Answer

Metaphase

Question 3

During anaphase, what mechanism is primarily responsible for the movement of chromosomes toward the spindle poles?

Accepted Answer

Depolymerization of kinetochore microtubules at the kinetochore end, allowing motor proteins to 'walk' chromosomes toward the poles.

Question 4

A cell cycle inhibitor causes an accumulation of cells in the G1 phase and a decrease in cells in the S phase. What is the most likely mechanism of action for this inhibitor?

Accepted Answer

The inhibitor downregulates cyclin D1, preventing the transition from G1 to S phase.

Question 5

Which equation best represents the relationship between the number of chromosomes in somatic cells ($$n_s) $$and gametes ($$n_g) in a $$diploid organism?

Accepted Answer

$$n_s = 2n_g$$

Question 6

Which of the following statements about cancer cells is TRUE?

Accepted Answer

Cancer cells can divide indefinitely in culture due to evasion of normal cell cycle controls and apoptosis.

Question 7

In animal cells, cytokinesis is accomplished by the formation of a cleavage furrow. Which cytoskeletal components are directly involved in this process?

Accepted Answer

Actin microfilaments and myosin molecules

Question 8

A cell is observed to have duplicated centrosomes, a nuclear envelope, and uncondensed chromatin. Which phase of the cell cycle is it most likely in?

Accepted Answer

G2 of interphase

Question 9

Which checkpoint in the cell cycle is most critical for determining whether a cell will proceed to divide or enter a non-dividing state?

Accepted Answer

G1 checkpoint

Question 10

A mutation causes a cell to produce a cyclin-Cdk complex that cannot be degraded. What is the most likely consequence for the cell?

Accepted Answer

The cell will continuously enter mitosis, leading to uncontrolled cell division.

Question 11

Which of the following best explains why binary fission in bacteria does not involve mitosis?

Accepted Answer

Bacteria lack a nucleus and mitotic spindle, so chromosome separation occurs without mitosis.

Question 12

During the S phase of interphase, which of the following occurs?

Accepted Answer

DNA replication

Question 13

Which of the following is a function of the kinetochore during mitosis?

Accepted Answer

It acts as a coupling device, connecting motor proteins to chromosomes for movement along spindle fibers.

Question 14

A plant cell is undergoing cytokinesis. Which structure is formed to separate the two daughter cells?

Accepted Answer

Cell plate

Question 15

Which of the following best describes the role of MPF (Maturation-Promoting Factor) in the cell cycle?

Accepted Answer

MPF is a cyclin-Cdk complex that triggers the cell's passage into the M phase by phosphorylating proteins.

Question 16

Which of the following equations correctly represents the change in DNA content per cell during the cell cycle, where $$C is $$the DNA content in G1 and $$2C is $$the DNA content after S phase?

Accepted Answer

$$C \rightarrow 2C$$ during S phase

Question 17

Which of the following is NOT a function of cell division in multicellular organisms?

Accepted Answer

Production of gametes with double the chromosome number of somatic cells

Question 18

Which of the following statements about the mitotic spindle is correct?

Accepted Answer

The mitotic spindle is composed of microtubules and associated proteins that control chromosome movement during mitosis.

Question 19

A patient is treated with chemotherapy that targets rapidly dividing cells. Which normal cell type is most likely to be affected, resulting in side effects?

Accepted Answer

Cells in the bone marrow producing new blood cells

The Cell Cycle: Structure, Regulation, and Division

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