Question 1

Which of the following best describes the main purpose of mitosis in multicellular eukaryotes?

Accepted Answer

To enable growth, development, and tissue repair by producing genetically identical cells

Question 2

During which phase of the cell cycle does DNA replication occur, and what is the result?

Accepted Answer

S phase; each chromosome consists of two sister chromatids

Question 3

A scientist observes a cell with condensed chromosomes aligned at the center of the cell, spindle fibers attached to kinetochores, and the nuclear envelope completely dissolved. Which stage of mitosis is this cell in?

Accepted Answer

Metaphase

Question 4

Which structure is responsible for holding sister chromatids together until anaphase?

Accepted Answer

Cohesin proteins

Question 5

What is the primary difference between binary fission in prokaryotes and mitosis in eukaryotes?

Accepted Answer

Binary fission does not involve mitotic spindle or distinct chromosome alignment stages

Question 6

A cell is observed to have exited the cell cycle and is no longer dividing but remains metabolically active. Which phase is this cell in?

Accepted Answer

G₀ phase

Question 7

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

Accepted Answer

M (spindle) checkpoint

Question 8

A mutation causes a cell to ignore density-dependent inhibition and anchorage dependence. What is the most likely outcome?

Accepted Answer

The cell may become cancerous and divide uncontrollably

Question 9

Which of the following best explains why mitosis evolved in eukaryotes but not in prokaryotes?

Accepted Answer

Eukaryotes have a nucleus and multiple linear chromosomes, requiring a more organized division system

Question 10

A patient is treated with a chemotherapy drug that prevents microtubule depolymerization. What stage of mitosis will be directly affected, and what is the likely cellular outcome?

Accepted Answer

Anaphase; sister chromatids will not separate properly

Question 11

Which of the following equations correctly represents the relationship between the number of chromosomes ($$n) $$and chromatids ($$c) in a $$human somatic cell during metaphase?

Accepted Answer

$$n = 46,\ c = 92$$

Question 12

Which event marks the transition from G₂ phase to mitosis in the cell cycle?

Accepted Answer

Activation of the cyclin-dependent kinase (Cdk) by cyclin to form MPF

Question 13

A researcher observes a cell with two nuclei, each containing a complete set of chromosomes, but the cytoplasm has not yet divided. Which process has occurred, and which has not?

Accepted Answer

Mitosis has occurred; cytokinesis has not

Question 14

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

Accepted Answer

It attaches spindle microtubules to the centromere of each chromatid

Question 15

In plant cells, cytokinesis is accomplished by which of the following mechanisms?

Accepted Answer

Formation of a cell plate from vesicles derived from the Golgi apparatus

Question 16

A mutation in a cell causes the G₁ checkpoint to be nonfunctional. Which of the following is a likely consequence?

Accepted Answer

Cells may divide uncontrollably, increasing cancer risk

Question 17

Which of the following best explains why cancer cells can divide indefinitely in culture?

Accepted Answer

They ignore normal regulatory signals such as checkpoints and density-dependent inhibition

Question 18

Which of the following is a direct result of the loss of function in tumor suppressor genes?

Accepted Answer

Cells fail to stop the cell cycle in response to DNA damage

Question 19

A cell is exposed to a growth factor such as PDGF after an injury. What is the most immediate effect on the cell cycle?

Accepted Answer

The cell passes the G₁ checkpoint and enters S phase

Cell Cycle and Mitosis: Structure, Function, and Regulation

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