Question 1

Which phase of the cell cycle is primarily responsible for the replication of genetic material, and what would be the consequence if this phase failed to occur before mitosis?

Accepted Answer

S-phase (Synthesis); daughter cells would lack sufficient DNA

Question 2

A researcher observes that a cell has an intact nuclear membrane, unwound DNA, and no visible spindle fibers. In which stage of the cell cycle is this cell most likely found?

Accepted Answer

Interphase

Question 3

Which of the following statements about the cell-cycle control system is FALSE?

Accepted Answer

The cell-cycle control system operates independently of the growth factors.

Question 4

If a chemical blocked the G1 checkpoint, what would be the most immediate effect on the cell cycle?

Accepted Answer

Cells would stall and never synthesize DNA.

Question 5

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

Accepted Answer

They are enzymes that phosphorylate other molecules, activating cell cycle processes when bound to cyclins.

Question 6

A cell is observed with chromosomes aligned at the center of the cell, all attached to spindle fibers. Which phase is this, and what is the significance of this arrangement?

Accepted Answer

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

Question 7

Which process is used by prokaryotic cells to divide, and how does it differ from mitosis?

Accepted Answer

Binary fission; it does not involve spindle fibers or a nuclear envelope

Question 8

What is the function of tumor suppressor genes such as p53 in the cell cycle?

Accepted Answer

They initiate apoptosis if a cell passes a checkpoint inappropriately.

Question 9

A scientist observes that cell division in a culture stops once the cell density reaches a certain level. What phenomenon is being observed?

Accepted Answer

Density-dependent inhibition

Question 10

If a cell reverses the changes to chromosomes seen in prophase, which phase is it in?

Accepted Answer

Telophase

Question 11

Which checkpoint ensures that all chromosomes are properly attached to the spindle before the cell proceeds with division?

Accepted Answer

M checkpoint

Question 12

What would most likely happen if a cell bypassed all cell cycle checkpoints?

Accepted Answer

It would divide uncontrollably, possibly leading to cancer.

Question 13

Which of the following is a real-world example of a growth factor, and what is its role?

Accepted Answer

Platelet-derived growth factor (PDGF); stimulates division of human fibroblast cells

Question 14

During which phase of mitosis do sister chromatids separate and move toward opposite poles?

Accepted Answer

Anaphase

Question 15

If a eukaryotic cell is observed to have two nuclei and is in the process of dividing its cytoplasm, which stage is it most likely in?

Accepted Answer

Cytokinesis

Question 16

Which of the following best explains why cancer cells are often used in research instead of normal cells?

Accepted Answer

They do not exhibit density-dependent inhibition or anchorage dependence, allowing them to divide indefinitely in culture.

Question 17

A cell is observed with chromosomes decondensing and the nuclear envelope reforming. Which phase is this?

Accepted Answer

Telophase

Question 18

Which of the following is true about the genome of a cell?

Accepted Answer

It consists of all the DNA in a cell, which may be a single DNA molecule in prokaryotes or multiple in eukaryotes.

Question 19

What is the main evolutionary significance of mitosis in eukaryotes?

Accepted Answer

It likely evolved from binary fission, as seen in prokaryotes.

Question 20

Which of the following best describes the role of checkpoints in the cell cycle?

Accepted Answer

They ensure the cell only proceeds to the next stage if conditions are favorable and previous steps are completed.

The Cell Cycle: Regulation, Phases, and Control Mechanisms

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