Question 1

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

Accepted Answer

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

Question 2

A researcher observes a cell with chromosomes aligned at the center of the cell, attached to spindle fibers from opposite poles. Which phase of mitosis is being observed, and what is the biological importance of this arrangement?

Accepted Answer

Metaphase; this arrangement ensures that each daughter cell will receive an identical set of chromosomes when the chromatids are separated.

Question 3

Which of the following best describes the role of cyclins in the regulation of the cell cycle?

Accepted Answer

Cyclins are regulatory proteins whose concentrations fluctuate throughout the cell cycle, activating checkpoints and allowing progression to the next phase.

Question 4

A mutation in the p53 gene is found in a patient's tumor cells. What is the most likely consequence of this mutation?

Accepted Answer

Cells will be unable to undergo apoptosis, increasing the risk of uncontrolled cell division and cancer.

Question 5

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

Accepted Answer

Animal cells form a contractile ring that pinches the cell in two, while plant cells build a cell plate that becomes the new cell wall.

Question 6

Which of the following best explains why nerve and muscle cells typically do not divide after reaching maturity?

Accepted Answer

They remain permanently in the $$G_0$$ phase, performing specialized functions without re-entering the cell cycle.

Question 7

A scientist is studying a cell that has lost contact inhibition and is forming a disorganized, multilayered mass. Which process has most likely failed in this cell?

Accepted Answer

Cell cycle regulation, resulting in uncontrolled cell division characteristic of cancer.

Question 8

Which of the following statements about homologous chromosomes is correct?

Accepted Answer

They are pairs of chromosomes, one from each parent, that carry genes for the same traits at the same loci.

Question 9

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

Accepted Answer

M checkpoint

Question 10

A cell is observed to have a high level of telomerase activity. What is the most likely consequence of this observation in the context of cancer biology?

Accepted Answer

The cell will be able to divide indefinitely, contributing to tumor formation.

Question 11

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

Accepted Answer

It is a form of asexual reproduction where the circular DNA replicates and the cell splits into two identical daughter cells.

Question 12

Which of the following is a key difference between benign and malignant tumors?

Accepted Answer

Malignant tumors can metastasize to distant organs, while benign tumors remain localized.

Question 13

Which of the following best explains why apoptosis is considered an important process in multicellular organisms?

Accepted Answer

It removes abnormal or damaged cells, preventing the development of cancer and maintaining tissue health.

Question 14

A cell is exposed to a growth factor at its plasma membrane. This is an example of which type of cell cycle control signal?

Accepted Answer

External signal

Question 15

During which phase of mitosis do sister chromatids separate and move toward opposite poles of the cell?

Accepted Answer

Anaphase

Question 16

Which of the following is a function of mitosis in multicellular organisms?

Accepted Answer

Growth, repair, and maintenance of tissues

Question 17

A cell is observed to have a single, circular DNA molecule attached to the plasma membrane. Which type of cell division will this cell most likely undergo?

Accepted Answer

Binary fission

Question 18

Which of the following best describes the relationship between mitosis and apoptosis in tissue homeostasis?

Accepted Answer

Mitosis increases cell number, while apoptosis decreases cell number, maintaining tissue balance.

Question 19

A cell is unable to proceed past the $$G_2$$ checkpoint. Which of the following is the most likely reason for this arrest?

Accepted Answer

The cell has not completed DNA replication or has detected DNA damage.

Question 20

Which of the following equations best represents the relationship between the number of chromosomes ($$n) $$and the number of chromatids ($$c) in a $$human cell during the S phase?

Accepted Answer

$$c = 2n$$

Chapter 9: The Cell Cycle & Cellular Reproduction – Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard