Question 1

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

Accepted Answer

DNA replication occurs during the S phase, allowing each chromosome to consist of two sister chromatids for accurate segregation during mitosis.

Question 2

Which structure is responsible for organizing the mitotic spindle in animal cells, and what is its role during mitosis?

Accepted Answer

The centrosome organizes the spindle microtubules, ensuring proper chromosome segregation.

Question 3

What is the function of the kinetochore during mitosis?

Accepted Answer

The kinetochore is a protein complex that attaches chromosomes to spindle microtubules, facilitating their movement during anaphase.

Question 4

Which equation best represents the change in chromosome number during mitosis in a human somatic cell?

Accepted Answer

$$2n \rightarrow 2n$$

Question 5

A researcher observes a cell with condensed chromosomes aligned at the center of the cell. Which phase is the cell in, and what is the significance of this alignment?

Accepted Answer

The cell is in metaphase, and the alignment ensures equal distribution of chromosomes to daughter cells.

Question 6

How does cytokinesis differ between plant and animal cells?

Accepted Answer

Animal cells form a cleavage furrow, while plant cells form a cell plate.

Question 7

Which checkpoint ensures that all chromosomes are properly attached to the spindle before proceeding to anaphase?

Accepted Answer

M checkpoint

Question 8

What is the role of cyclin-dependent kinases (Cdks) in the cell cycle?

Accepted Answer

Cdks phosphorylate target proteins only when bound to cyclins, regulating cell cycle transitions.

Question 9

A mutation in the p53 tumor suppressor gene can lead to cancer. Which of the following best explains why?

Accepted Answer

p53 normally activates DNA repair and cell cycle arrest; its loss allows cells with damaged DNA to divide uncontrollably.

Question 10

Which of the following is a plausible consequence of a mutation that converts a proto-oncogene to an oncogene?

Accepted Answer

Increased cell division due to hyperactive signaling pathways.

Question 11

Binary fission in bacteria differs from mitosis in eukaryotes in which major way?

Accepted Answer

Binary fission does not involve a mitotic spindle, while mitosis does.

Question 12

A cell is exposed to a chemotherapeutic drug that inhibits microtubule depolymerization. What is the most likely effect on mitosis?

Accepted Answer

Chromosomes will fail to move to opposite poles during anaphase.

Question 13

Which of the following best describes the relationship between chromatin, chromosomes, and chromatids?

Accepted Answer

Chromatin is the DNA-protein complex; chromosomes are condensed chromatin; chromatids are duplicated chromosomes joined at the centromere.

Question 14

Which equation represents the change in chromosome number during meiosis in humans?

Accepted Answer

$$2n \rightarrow n$$

Question 15

A patient inherits a mutant allele of the BRCA1 gene. What is the most likely consequence?

Accepted Answer

Increased risk of developing certain cancers due to impaired DNA repair.

Question 16

Which of the following is a real-world example of cell division functioning in tissue repair?

Accepted Answer

Skin cells dividing to heal a cut.

Question 17

What is the primary difference between benign and malignant tumors?

Accepted Answer

Malignant tumors invade surrounding tissues and can metastasize, while benign tumors remain localized.

Question 18

Which of the following best explains why cancer incidence increases with age?

Accepted Answer

Multiple mutations accumulate over time, increasing the likelihood of cancer development.

Question 19

Which of the following is a function of tumor-suppressor proteins?

Accepted Answer

Repairing damaged DNA and inhibiting cell cycle progression.

The Cell Cycle and Molecular Biology of Cancer: Study Notes for General Biology

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