$$\text{Total chromosomes} = 2 \times 23 = 46$$

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

A human cell in the S phase of the cell cycle has just finished duplicating its DNA. How many chromatids are present in the cell at this point?

Accepted Answer

$$92$$

Question 3

Which of the following best describes the G0 phase of the cell cycle?

Accepted Answer

A non-dividing, non-growing stage that some cells enter permanently

Question 4

During which phase of the cell cycle do chromosomes become visible as distinct structures due to condensation?

Accepted Answer

Mitotic phase

Question 5

If a mutation prevents the synthesis of histone proteins, which process would be most directly affected?

Accepted Answer

Chromatin compaction

Question 6

Which of the following equations correctly represents the total number of chromosomes in a human somatic cell?

Accepted Answer

$$	ext{Total chromosomes} = 2 	imes 23 = 46$$

Question 7

Which of the following statements about genes is correct?

Accepted Answer

Genes are short segments of DNA that code for proteins

Question 8

A neuron in an adult human is most likely found in which phase of the cell cycle?

Accepted Answer

G0 phase

Question 9

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

Accepted Answer

Chromatin is condensed to form chromosomes during mitosis

Question 10

If a cell fails to complete the G2 phase, which of the following is the most likely consequence?

Accepted Answer

The cell will not prepare properly for division

Question 11

Which of the following base pairing rules is correct for DNA?

Accepted Answer

$$A = T, C = G$$

Question 12

A scientist observes a cell with 8 chromosomes (4 pairs) during the S phase. How many chromatids will be present after DNA replication?

Accepted Answer

$$16$$

Question 13

Which event marks the transition from interphase to the mitotic phase?

Accepted Answer

Chromosome condensation and nuclear division

Question 14

Which of the following is NOT a function of the G1 phase?

Accepted Answer

DNA duplication

Question 15

Which process ensures that each daughter cell receives an identical set of chromosomes during cell division?

Accepted Answer

Mitosis

Question 16

A mutation causes a cell to skip the S phase. What is the most likely outcome?

Accepted Answer

The cell will not duplicate its DNA and may produce daughter cells with incomplete genetic material

Question 17

Which of the following best explains why neurons and osteocytes rarely divide after adolescence?

Accepted Answer

They remain permanently in the G0 phase

Question 18

Which of the following is the correct sequence of events during the mitotic phase?

Accepted Answer

Mitosis, cytokinesis

Question 19

If a human cell is observed with condensed chromosomes aligned at the center of the cell, which phase is it most likely in?

Accepted Answer

Mitotic phase

Question 20

Which of the following statements about the human genome is correct?

Accepted Answer

It contains approximately 20,000–21,000 genes located on 46 chromosomes

Cell Cycle, DNA Structure, and Chromosomes: Study Notes for Human Biology

Study Guide - Practice Questions