Question 1

Which phase of the cell cycle is primarily responsible for DNA replication, and what is the main event that occurs during this phase?

Accepted Answer

S phase; DNA is duplicated

Question 2

During which phase of the cell cycle do most cells in the human body remain if they are not actively dividing, and what is a real-life example of a cell type that stays in this phase permanently?

Accepted Answer

G0 phase; neurons

Question 3

What is the correct sequence of events in the cell cycle for a cell that is actively dividing?

Accepted Answer

G1 → S → G2 → Mitotic phase

Question 4

If a mutation prevents the formation of histone proteins, what would be the most immediate effect on DNA structure during interphase?

Accepted Answer

DNA would not be able to compact into chromatin

Question 5

A scientist observes a cell with visible chromosomes, each consisting of two identical sister chromatids joined at a centromere. Which phase is this cell most likely in?

Accepted Answer

Mitotic phase

Question 6

How many chromosomes are present in a typical human somatic cell during G2 phase, and why?

Accepted Answer

$$92$$; because each of the $$46$$ chromosomes has been duplicated but not yet divided

Question 7

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

Accepted Answer

It holds sister chromatids together until they are separated during mitosis

Question 8

A patient’s bone cells (osteocytes) are found to be in a non-dividing state for decades. Which phase of the cell cycle are these cells most likely in?

Accepted Answer

G0 phase

Question 9

Which of the following statements about genes is correct?

Accepted Answer

A gene is a short segment of DNA that contains the code for making one or more proteins

Question 10

If a cell spends 8 hours in S phase, 6 hours in G1, and 6 hours in G2, how long does it spend in interphase?

Accepted Answer

$$20$$ hours

Question 11

Which of the following best explains why chromosomes are not visible during interphase?

Accepted Answer

They exist as long, thin chromatin fibers that are not condensed

Question 12

What is the primary function of cytokinesis in the cell cycle?

Accepted Answer

To divide the cytoplasm and form two new cells

Question 13

A mutation causes a cell to skip the G2 phase. Which of the following is a likely consequence?

Accepted Answer

The cell may not properly prepare for division, leading to errors in mitosis

Question 14

Which of the following equations correctly represents the number of base pairs in the human genome?

Accepted Answer

$$3 	imes 10^9$ base pairs

Question 15

If a cell fails to duplicate its DNA during S phase but proceeds to mitosis, what is the most likely outcome?

Accepted Answer

The daughter cells will have incomplete or missing genetic material

Question 16

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

Accepted Answer

Chromatin is DNA wrapped around histones; chromosomes are condensed chromatin; genes are segments of DNA

Question 17

A researcher is studying a fruit fly cell and observes 8 chromosomes during mitosis. How many chromosomes would you expect to find in a human cell during the same phase?

Accepted Answer

$$46$$ chromosomes

Question 18

Which phase of the cell cycle is characterized by the cell growing to its largest size and preparing for DNA replication?

Accepted Answer

G1 phase

Question 19

If a cell spends 45 minutes in the mitotic phase and 23 hours in interphase, what percentage of the cell cycle is spent in mitosis? (Round to the nearest whole number)

Accepted Answer

$$3\%$$

Question 20

Which of the following statements about the cell cycle is FALSE?

Accepted Answer

Most cell growth occurs during the S phase

Cell Cycle, DNA Structure, and Chromosome Organization

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