Question 1

Which of the following best describes the difference between sister chromatids and homologous chromosomes?

Accepted Answer

Sister chromatids are identical copies of a chromosome joined at the centromere, while homologous chromosomes are similar but not identical chromosomes inherited from each parent.

Question 2

A diploid cell with 8 chromosomes enters G1 phase. How many DNA double helices are present in this cell during G1, G2, and metaphase, respectively?

Accepted Answer

8 in G1, 16 in G2, 16 in metaphase

Question 3

During which phase of the cell cycle does DNA replication occur, and what is the significance of this event for mitosis?

Accepted Answer

S phase; it ensures that each daughter cell receives an identical set of chromosomes after mitosis.

Question 4

Which structure is directly responsible for physically separating sister chromatids during mitosis?

Accepted Answer

The mitotic spindle, composed of microtubules

Question 5

What is the primary role of the cytoskeleton during cytokinesis in animal cells?

Accepted Answer

It forms a contractile ring of actin and myosin that pinches the cell into two daughter cells.

Question 6

MPF (M-phase promoting factor) is a key regulator of the cell cycle. Which of the following statements about MPF is correct?

Accepted Answer

MPF is composed of cyclin and cyclin-dependent kinase (Cdk), and its activity peaks at the onset of M phase.

Question 7

Which type of protein transfers a phosphate group to a substrate, and what is a key example involved in cell cycle regulation?

Accepted Answer

Kinase; cyclin-dependent kinase (Cdk)

Question 8

Cell cycle checkpoints are critical for maintaining genomic integrity. Which checkpoint is primarily responsible for ensuring that DNA is undamaged before replication, and which protein is a key regulator at this checkpoint?

Accepted Answer

G1 checkpoint; p53

Question 9

A mutation in the Rb protein leads to loss of its function. What is the most likely consequence for the cell cycle?

Accepted Answer

The cell may proceed through the G1 checkpoint without proper regulation, increasing the risk of uncontrolled cell division.

Question 10

Which of the following best explains why not all cancer cells have mutations in the same genes?

Accepted Answer

Cancer can result from defects in multiple pathways that regulate the cell cycle, so different mutations can lead to similar uncontrolled growth.

Question 11

Growth factors play a crucial role in cell cycle regulation. What is their primary function?

Accepted Answer

They stimulate cells to pass the G1 checkpoint and enter the cell cycle.

Question 12

A researcher observes that a cell line continues to divide even in the absence of growth factors. Which checkpoint is most likely defective in these cells, and what is the implication?

Accepted Answer

G1 checkpoint; the cells have lost normal control over cell division, a hallmark of cancer.

Question 13

Which event would most likely lead to cell cycle arrest at the G2 checkpoint?

Accepted Answer

Detection of unreplicated or damaged DNA

Question 14

During which phase of mitosis do sister chromatids separate, and what structure is responsible for this movement?

Accepted Answer

Anaphase; the mitotic spindle

Question 15

Which of the following best describes the change in MPF concentration during the cell cycle?

Accepted Answer

MPF concentration rises during interphase, peaks at the start of M phase, and declines sharply during M phase due to cyclin degradation.

Question 16

A cell is observed to have a high level of active cyclin-dependent kinase (Cdk) but low cyclin concentration. What is the most likely explanation?

Accepted Answer

The cell is in M phase, and cyclin is being degraded, leading to inactivation of Cdk soon.

Question 17

Which of the following scenarios best illustrates the cellular basis of cancer?

Accepted Answer

A cell accumulates mutations that disable cell cycle checkpoints, allowing uncontrolled division.

Question 18

Which of the following equations correctly represents the relationship between chromosome number ($$n$$), DNA content ($$C$$), and the cell cycle phases in a diploid organism?

Accepted Answer

During G1: $$n = 2$$, $$C = 2$$; During G2: $$n = 2$$, $$C = 4$$

Question 19

A scientist treats cells with a drug that prevents microtubule polymerization. What is the most likely effect on mitosis?

Accepted Answer

Sister chromatids will not be separated because the mitotic spindle cannot form.

Question 20

Which of the following best explains why MPF activity is tightly regulated during the cell cycle?

Accepted Answer

To ensure that mitosis only occurs when the cell is ready, preventing errors in chromosome segregation.

BIOL 141 Chapter 12 Study Guide – Cell Cycle, Mitosis, and Cancer

Study Guide - Practice Questions

Study Guide - Flashcards