Question 1

Which of the following best describes the main difference between mitosis and meiosis in terms of genetic outcome?

Accepted Answer

Mitosis produces genetically identical daughter cells, while meiosis produces genetically different cells with half the hereditary material.

Question 2

During which phase of the cell cycle does DNA replication occur, and what is the state of the chromosomes during this phase?

Accepted Answer

DNA replication occurs during the S phase, and chromosomes are uncoiled as chromatin.

Question 3

A researcher observes a cell with chromosomes aligned at the metaphase plate, each attached to spindle fibers from opposite poles. Which phase is this cell in, and what is the significance of this arrangement?

Accepted Answer

The cell is in metaphase, and this arrangement ensures that sister chromatids will be separated equally to each daughter cell.

Question 4

Which of the following events occurs during anaphase of mitosis?

Accepted Answer

Sister chromatids are pulled apart toward opposite poles by shrinking kinetochore microtubules.

Question 5

In animal cells, cytokinesis is accomplished by which of the following mechanisms?

Accepted Answer

Constriction of a ring of actin and myosin filaments, forming a cleavage furrow.

Question 6

Which checkpoint is considered the most important for determining whether a cell will divide, and what are two key factors it assesses?

Accepted Answer

The G$$_1$$ checkpoint; it assesses cell size and DNA damage.

Question 7

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

Accepted Answer

Cells may divide uncontrollably because the G$$_1$$ checkpoint fails to stop damaged cells.

Question 8

Which of the following best explains how MPF (M-phase promoting factor) activity is regulated during the cell cycle?

Accepted Answer

MPF activity rises and falls as cyclin concentration cycles, while Cdk concentration remains constant.

Question 9

Which of the following is a direct result of the activation of MPF in a cell?

Accepted Answer

Phosphorylation of target proteins that initiate mitosis.

Question 10

A scientist treats cells with a drug that prevents the attachment of microtubules to kinetochores. Which checkpoint will most likely prevent these cells from proceeding, and why?

Accepted Answer

The M-phase checkpoint, because not all kinetochores are attached to the spindle apparatus.

Question 11

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

Accepted Answer

Binary fission is similar to eukaryotic M phase, involving chromosome replication and division of the cytoplasm.

Question 12

If a cell fails to degrade cyclin after mitosis, what is the most likely outcome?

Accepted Answer

MPF will remain active, potentially causing the cell to re-enter mitosis prematurely.

Question 13

Which of the following best describes the role of kinases and phosphatases in cell cycle regulation?

Accepted Answer

Kinases add phosphate groups to proteins, turning them on; phosphatases remove phosphate groups, turning them off.

Question 14

A cell is observed with decondensing chromosomes and two newly forming nuclear envelopes. Which phase is this, and what process typically follows?

Accepted Answer

Telophase; cytokinesis

Question 15

Which of the following is NOT a factor assessed at the G$$_1$$ checkpoint?

Accepted Answer

Attachment of kinetochores to spindle fibers

Question 16

If a cell's chromosomes are not fully separated at the end of anaphase, which checkpoint is most likely to halt the cell cycle?

Accepted Answer

M-phase checkpoint between anaphase and telophase

Question 17

Which of the following best explains why cancer cells often have mutations in genes that regulate cell cycle checkpoints?

Accepted Answer

These mutations allow cells to bypass checkpoints, leading to uncontrolled cell division.

Question 18

Which of the following is true regarding the concentration of cyclin and Cdk during the cell cycle?

Accepted Answer

Cyclin concentration cycles, peaking in M phase, while Cdk concentration remains constant.

Question 19

Which process is responsible for marking cyclin for destruction, thereby inactivating MPF?

Accepted Answer

Ubiquitination by an enzyme complex (APC/C)

The Cell Cycle: Regulation and Mechanisms of Eukaryotic Cell Division

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