Question 1

Which of the following best describes the role of histone proteins in eukaryotic cells?

Accepted Answer

They package DNA into nucleosomes, regulate gene expression, and protect DNA from damage.

Question 2

During which phase of the cell cycle does DNA replication occur, and what is the consequence if this phase is skipped?

Accepted Answer

DNA replication occurs during S phase; skipping it results in daughter cells lacking complete genomes.

Question 3

A cell is observed with chromosomes aligned at the metaphase plate, spindle fibers fully attached, and maximal chromosome condensation. Which checkpoint is active at this stage, and what is its primary function?

Accepted Answer

M checkpoint; ensures all chromosomes are properly attached to spindle fibers to prevent unequal chromosome separation.

Question 4

What is the function of the kinetochore during mitosis?

Accepted Answer

It serves as the attachment point for spindle microtubules, enabling chromosome movement.

Question 5

Which equation correctly represents the chromosome number in somatic cells versus gametes for a species with $$2n = 46$$?

Accepted Answer

$$2n = 46$$ for somatic cells, $$n = 23$$ for gametes

Question 6

A mutation prevents the degradation of cyclin during anaphase. What is the most likely outcome for the cell?

Accepted Answer

The cell will fail to terminate the M phase, potentially leading to uncontrolled division.

Question 7

Which of the following is NOT a function of cell division in multicellular eukaryotes?

Accepted Answer

Production of oxygen for cellular respiration

Question 8

What is the primary difference between mitosis and meiosis as shown in the diagram?

Accepted Answer

Mitosis produces two genetically identical daughter cells, while meiosis produces four genetically nonidentical daughter cells with half the chromosome number.

Question 9

Which of the following best explains why cancer cells can form tumors?

Accepted Answer

They do not respond to normal cell cycle control mechanisms and can divide indefinitely.

Question 10

During anaphase, which enzyme is activated to cleave cohesin and allow sister chromatids to separate?

Accepted Answer

Separase

Question 11

A cell is exposed to platelet-derived growth factor (PDGF) in culture. What is the expected response?

Accepted Answer

The cell will begin dividing in response to the external growth factor.

Question 12

Which checkpoint is most likely to prevent a cell with damaged DNA from entering mitosis?

Accepted Answer

G2 checkpoint

Question 13

If a cell fails to receive a go-ahead signal at the G1 checkpoint, what happens?

Accepted Answer

It exits the cell cycle and enters a nondividing state called G0.

Question 14

Which of the following is a real-world consequence of chromosome mis-segregation during mitosis?

Accepted Answer

Development of genetic disorders such as Down syndrome.

Question 15

Which of the following best describes the relationship between cyclins and Cdks?

Accepted Answer

Cyclins activate Cdks, which then phosphorylate target proteins to drive cell cycle progression.

Question 16

Which type of microtubule is responsible for elongating the cell during anaphase?

Accepted Answer

Non-kinetochore microtubules

Question 17

In plant cells, cytokinesis occurs by the formation of a cell plate. What is the equivalent structure in animal cells?

Accepted Answer

Cleavage furrow

Question 18

Which phase of mitosis is characterized by the reformation of the nuclear envelope and decondensation of chromosomes?

Accepted Answer

Telophase

Question 19

A cell is observed to have two sets of chromosomes, each set at opposite poles, and chromosomes are decondensing. What process is likely occurring?

Accepted Answer

Telophase

Question 20

Which of the following best describes the function of the spindle assembly checkpoint (SAC)?

Accepted Answer

It ensures all kinetochores are attached and under tension before anaphase begins.

The Cell Cycle: Structure, Function, and Regulation

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