Question 1

Which phase of the cell cycle is primarily responsible for the synthesis of DNA, and what is the main outcome of this phase?

Accepted Answer

S phase; the cell duplicates its DNA, resulting in two sister chromatids for each chromosome.

Question 2

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

Accepted Answer

Metaphase; it ensures that each daughter cell will receive one copy of each chromosome.

Question 3

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

Accepted Answer

Cdks are enzymes that, when bound to cyclins, phosphorylate target proteins to regulate cell cycle progression.

Question 4

A researcher treats dividing animal cells with a drug that prevents microtubule depolymerization. What is the most likely effect on mitosis?

Accepted Answer

Sister chromatids will not separate during anaphase, causing cells to arrest in metaphase.

Question 5

Which checkpoint is considered the most important for determining whether a cell will divide, and what happens if the cell does not receive the go-ahead signal at this checkpoint?

Accepted Answer

G1 checkpoint; the cell enters the G0 phase and stops dividing.

Question 6

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

Accepted Answer

Animal cells use a contractile ring of actin microfilaments to form a cleavage furrow, while plant cells build a cell plate from vesicles.

Question 7

A mutation causes cells to ignore density-dependent inhibition and anchorage dependence. What is the most likely consequence?

Accepted Answer

Cells will continue to divide uncontrollably, potentially leading to cancer.

Question 8

Which of the following best explains why chemotherapy often causes side effects such as hair loss and gastrointestinal distress?

Accepted Answer

Chemotherapy drugs target all rapidly dividing cells, including normal cells like hair follicles and intestinal lining.

Question 9

Which experiment provided evidence that diffusible signal molecules control the cell cycle?

Accepted Answer

Fusing cells in different phases and observing synchronization of their cell cycles.

Question 10

What is the function of the centromere during mitosis?

Accepted Answer

It serves as the attachment point for spindle fibers via the kinetochore, ensuring proper chromosome segregation.

Question 11

If a cell is observed to have condensed chromosomes, a fragmented nuclear envelope, and spindle fibers attaching to kinetochores, which phase is it most likely in?

Accepted Answer

Prometaphase

Question 12

Which of the following best describes the outcome of binary fission in prokaryotes?

Accepted Answer

Two genetically identical daughter cells are produced.

Question 13

Which protein complex is responsible for triggering the onset of anaphase by ensuring all kinetochores are attached to spindle fibers?

Accepted Answer

Anaphase-promoting complex (APC)

Question 14

A cell is exposed to platelet-derived growth factor (PDGF) but lacks nutrients. What is the most likely outcome?

Accepted Answer

The cell will not divide because nutrients are also required to pass the G1 checkpoint.

Question 15

Which of the following events occurs during anaphase of mitosis?

Accepted Answer

Sister chromatids separate and move toward opposite poles.

Question 16

What is the main reason why multicellular organisms require cell division?

Accepted Answer

For growth, development, and maintenance of tissues.

Question 17

Which of the following best describes the relationship between cyclin concentration and MPF activity?

Accepted Answer

MPF activity increases as cyclin concentration rises, peaking at the onset of mitosis.

Question 18

A cell is observed with two nuclei, chromosomes decondensing, and a cleavage furrow forming. Which phase is this cell in?

Accepted Answer

Telophase and cytokinesis

Question 19

Which of the following is a hallmark of cancer cells compared to normal cells?

Accepted Answer

They can divide indefinitely and often ignore cell cycle checkpoints.

The Cell Cycle: Mechanisms and Regulation of Cell Division

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