Question 1

Which of the following best describes the difference between chromatin and chromosomes in eukaryotic cells?

Accepted Answer

Chromatin is unwound DNA packaged with proteins and is invisible under a microscope, while chromosomes are condensed and visible only during cell division.

Question 2

A human somatic cell in G1 phase contains 46 chromosomes. After DNA replication in S phase, how many sister chromatids are present in the cell?

Accepted Answer

$$92$$

Question 3

Which phase of the cell cycle is the longest and what major event occurs during this phase?

Accepted Answer

G1 phase; cell grows and carries out normal functions

Question 4

During which phase of mitosis do chromosomes align 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 5

Which structure is responsible for organizing the mitotic spindle in animal cells?

Accepted Answer

Centrosome

Question 6

What is the primary difference between cytokinesis in plant and animal cells?

Accepted Answer

Plant cells form a cell plate from Golgi-derived vesicles, while animal cells form a cleavage furrow that pinches the cell in two.

Question 7

Which checkpoint in the cell cycle is known as the 'restriction point' and what is its significance?

Accepted Answer

G1 checkpoint; it determines whether the cell will commit to division based on external signals

Question 8

A mutation in a gene encoding a cyclin-dependent kinase (CDK) that prevents it from binding cyclin would most likely result in which outcome?

Accepted Answer

Cell cycle arrest at a checkpoint

Question 9

Which of the following best explains why errors in cell cycle regulation can lead to cancer?

Accepted Answer

They allow cells to divide uncontrollably due to failure of checkpoints and tumor suppressors.

Question 10

In binary fission, how do bacterial cells ensure that each daughter cell receives a copy of the chromosome?

Accepted Answer

The two copies of the chromosome attach to opposite sides of the plasma membrane before the cell divides.

Question 11

Which of the following is true about the role of cyclins in the cell cycle?

Accepted Answer

Cyclins are only expressed during certain phases and activate CDKs to drive the cell cycle forward.

Question 12

A scientist observes a cell with condensed chromosomes, a dissolving nuclear envelope, and spindle fibers attaching to kinetochores. Which phase is this cell in?

Accepted Answer

Prometaphase

Question 13

If a cell's DNA is damaged and the damage is not repaired, what is the most likely outcome at the cell cycle checkpoint?

Accepted Answer

The cell will halt at the checkpoint and not proceed to the next phase.

Question 14

Which of the following best describes the relationship between oncogenes and tumor suppressors?

Accepted Answer

Oncogenes promote cell growth and division, while tumor suppressors restrain cell growth and division.

Question 15

During which phase of mitosis do sister chromatids become independent chromosomes and move toward opposite poles?

Accepted Answer

Anaphase

Question 16

A cell is observed to have two nuclei forming and chromosomes beginning to de-condense. Which phase is this cell most likely in?

Accepted Answer

Telophase

Question 17

Which of the following events occurs during the S phase of the cell cycle?

Accepted Answer

DNA is replicated, resulting in two identical sister chromatids for each chromosome.

Question 18

Which of the following best explains why nerve and muscle cells rarely divide in mature animals?

Accepted Answer

They are typically in the G0 (quiescent) phase and do not re-enter the cell cycle.

Question 19

If a mutation caused the G1 checkpoint to be nonfunctional, what would be a likely consequence for the cell?

Accepted Answer

The cell might divide uncontrollably, increasing the risk of cancer.

Question 20

Which of the following is a correct sequence of events during mitosis?

Accepted Answer

Prophase → Prometaphase → Metaphase → Anaphase → Telophase

ch 7Cell Division and the Cell Cycle: Structure, Function, and Regulation

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