Question 1

Which of the following best describes the main purpose of the cell cycle in multicellular organisms?

Accepted Answer

To allow cells to grow, replicate their DNA, and divide, ensuring genetic continuity and tissue maintenance

Question 2

During which phase of the cell cycle does DNA replication occur?

Accepted Answer

S phase

Question 3

A scientist observes a cell with condensed chromosomes aligned at the center of the cell, attached to spindle fibers from opposite poles. Which stage of mitosis is this cell in?

Accepted Answer

Metaphase

Question 4

Which of the following statements about cyclin-dependent kinases (Cdks) is correct?

Accepted Answer

Cdks require binding to cyclin to become active

Question 5

What is the role of the p53 protein at the G1 checkpoint?

Accepted Answer

It can pause the cell cycle or initiate apoptosis if DNA is damaged

Question 6

Which of the following events distinguishes cytokinesis in plant cells from animal cells?

Accepted Answer

Formation of a cell plate from Golgi-derived vesicles

Question 7

If a human cell has 46 chromosomes at the start of the cell cycle, how many chromatids will be present after DNA replication but before mitosis?

Accepted Answer

$$92$$

Question 8

Which checkpoint ensures that all chromosomes are properly attached to the spindle apparatus before sister chromatids separate?

Accepted Answer

M-phase (metaphase-anaphase) checkpoint

Question 9

A mutation causes the loss of function of a tumor suppressor gene. What is the most likely consequence?

Accepted Answer

Cells may divide uncontrollably, increasing cancer risk

Question 10

Which of the following best explains why rapidly dividing cells, such as embryonic cells, have a very short or absent G1 phase?

Accepted Answer

They need to divide quickly and therefore minimize the time spent growing and preparing for DNA synthesis

Question 11

Which of the following is a direct result of the action of kinases during the cell cycle?

Accepted Answer

Attachment of phosphate groups to proteins, activating them

Question 12

A cell is observed to have its nuclear envelope breaking down and microtubules attaching to kinetochores. Which phase is this?

Accepted Answer

Prometaphase

Question 13

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

Accepted Answer

Sister chromatids are identical copies formed by DNA replication; homologous chromosomes are similar but may have different alleles

Question 14

Which of the following is NOT a factor that affects passage through the G1 checkpoint?

Accepted Answer

Attachment of spindle fibers

Question 15

What is the main function of the spindle apparatus during mitosis?

Accepted Answer

To move and separate chromosomes

Question 16

Which of the following best explains why cancer cells can divide uncontrollably?

Accepted Answer

They have defects in cell cycle control genes, such as oncogenes and tumor suppressors

Question 17

Which process is most similar to bacterial binary fission in eukaryotic cells?

Accepted Answer

Mitosis

Question 18

A cell fails to remove the inhibitory phosphate from MPF at the G2 checkpoint. What is the likely outcome?

Accepted Answer

The cell will remain in G2 phase

Question 19

Which of the following is a real-world example of the importance of cell cycle checkpoints?

Accepted Answer

The prevention of tumor formation by detecting and repairing DNA damage before cell division

Question 20

Which of the following best describes the role of cohesins during mitosis?

Accepted Answer

They hold sister chromatids together until anaphase

The Eukaryotic Cell Cycle: Mitosis, Regulation, and Cancer

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