Question 1

Which of the following best describes the difference between a chromosome, chromatid, and chromatin in eukaryotic cells?

Accepted Answer

A chromosome is a structure made of DNA and protein, a chromatid is one of two identical halves of a duplicated chromosome, and chromatin is the less condensed form of DNA and protein found during interphase.

Question 2

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

Accepted Answer

DNA replication occurs during the S phase, resulting in duplicated chromosomes composed of sister chromatids.

Question 3

Which checkpoint in the cell cycle is primarily responsible for ensuring that all chromosomes are properly attached to the spindle before anaphase begins?

Accepted Answer

M checkpoint

Question 4

What is the primary function of the mitotic spindle during mitosis?

Accepted Answer

To separate sister chromatids and move them to opposite poles of the cell

Question 5

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

Accepted Answer

They ignore cell cycle checkpoints due to mutations in genes such as proto-oncogenes and tumor suppressor genes.

Question 6

A mutation in the ras proto-oncogene can lead to which of the following outcomes?

Accepted Answer

Uncontrolled cell division due to a hyperactive Ras protein.

Question 7

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

Accepted Answer

Plant cells form a cell plate, while animal cells form a cleavage furrow.

Question 8

Which of the following is a function of the p53 tumor suppressor protein?

Accepted Answer

Prevents cells with damaged DNA from dividing by activating DNA repair, cell cycle arrest, or apoptosis.

Question 9

Which of the following best describes the process of binary fission in bacteria?

Accepted Answer

The chromosome replicates, and the plasma membrane pinches inward to divide the cell into two.

Question 10

A cell is observed with chromosomes aligned at the center of the cell, attached to spindle fibers from opposite poles. Which phase is this cell in?

Accepted Answer

Metaphase

Question 11

Which of the following equations correctly represents the change in chromosome number during mitosis in a human somatic cell (2n = 46)?

Accepted Answer

$$46 \rightarrow 92 \rightarrow 46$$

Question 12

Which of the following is NOT a typical function of tumor suppressor genes?

Accepted Answer

Stimulating cell division

Question 13

Which of the following best explains why multiple mutations are usually required for the development of cancer?

Accepted Answer

Multiple mutations are needed to activate oncogenes and inactivate several tumor suppressor genes, disrupting cell cycle control.

Question 14

Which of the following best describes the role of cyclin-dependent kinases (Cdks) in the cell cycle?

Accepted Answer

Cdks must bind to cyclins to become active and regulate progression through cell cycle checkpoints.

Question 15

A researcher observes a cell with a disassembled nuclear envelope, chromosomes attached to spindle microtubules at kinetochores, and chromosomes beginning to move toward the center of the cell. Which phase is this?

Accepted Answer

Prometaphase

Question 16

Which of the following scenarios would most likely result from a loss-of-function mutation in a tumor suppressor gene?

Accepted Answer

The cell divides uncontrollably, increasing the risk of cancer.

Question 17

Which of the following is a real-world example of how cell division is important for tissue renewal?

Accepted Answer

The healing of a skin wound through the production of new skin cells.

Question 18

Which of the following best describes the difference between benign and malignant tumors?

Accepted Answer

Malignant tumors can metastasize to other parts of the body, while benign tumors remain localized.

Question 19

Which of the following is a direct consequence of a cell failing to pass the G1 checkpoint?

Accepted Answer

The cell enters the G0 phase and stops dividing.

Question 20

Which of the following genetic changes can convert a proto-oncogene into an oncogene?

Accepted Answer

A point mutation that increases the activity of the protein product.

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

Guida di studio - Domande di pratica

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