Question 1

During which subphase of interphase does DNA replication occur, and what is the significance of this process for cell division?

Accepted Answer

S (synthetic) phase; it duplicates the genetic material so each daughter cell receives a complete set of chromosomes.

Question 2

Which checkpoint in the cell cycle is considered the most important for determining whether a cell will proceed to division, and what happens if a cell does not pass this checkpoint?

Accepted Answer

G\_1 checkpoint (restriction point); the cell enters G\_0 phase and ceases division.

Question 3

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

Accepted Answer

They activate cyclins, which then trigger enzyme cascades preparing the cell for division.

Question 4

Which of the following best describes semiconservative DNA replication?

Accepted Answer

Each new DNA molecule consists of one old strand and one new strand.

Question 5

During mitosis, at which stage do the centromeres of chromosomes split and sister chromatids become separate chromosomes?

Accepted Answer

Anaphase

Question 6

A cell is observed to have condensed chromatin, a broken nuclear envelope, and microtubules attaching to kinetochores. Which phase of mitosis is this cell most likely in?

Accepted Answer

Late prophase

Question 7

Which of the following is a direct result of contact inhibition in normal cells?

Accepted Answer

Cells stop dividing when they come into contact with other cells.

Question 8

What is the function of telomerase, and why is its activity significant in cancer cells?

Accepted Answer

It lengthens telomeres, allowing unlimited cell division and contributing to cancer cell immortality.

Question 9

Which process involves the removal of nonfunctional organelles and cytoplasmic debris by forming autophagosomes?

Accepted Answer

Autophagy

Question 10

A protein is marked for destruction by ubiquitin and then disassembled. Which cellular structure is responsible for this process?

Accepted Answer

Proteasome

Question 11

Which of the following best describes the role of mRNA in protein synthesis?

Accepted Answer

It carries the DNA code from the nucleus to the cytoplasm for translation.

Question 12

What is the correct sequence of events in translation at the ribosome?

Accepted Answer

Initiation, elongation, termination

Question 13

If a tRNA has the anticodon UAU, which mRNA codon will it bind to during translation?

Accepted Answer

AUA

Question 14

Which of the following is true regarding the genetic code and codons?

Accepted Answer

There are 64 possible codons, but only 20 amino acids, so some amino acids are coded by multiple codons.

Question 15

During transcription, which enzyme synthesizes mRNA from the DNA template strand?

Accepted Answer

RNA polymerase

Question 16

Which of the following statements about exons and introns is correct?

Accepted Answer

Exons are coding regions that remain in mature mRNA after introns are removed.

Question 17

A cell is observed to have a cleavage furrow forming due to the contraction of actin microfilaments. Which process is occurring?

Accepted Answer

Cytokinesis

Question 18

Which theory of aging suggests that free radicals produced in mitochondria diminish energy production over time?

Accepted Answer

Mitochondrial theory of aging

Question 19

What is the primary function of the rough endoplasmic reticulum (ER) in protein synthesis?

Accepted Answer

It modifies and packages newly synthesized proteins for transport.

Question 20

Which equation correctly represents the number of possible codons given four bases and three positions in a codon?

Accepted Answer

$$4^3 = 64$

Cell Cycle, DNA Replication, and Protein Synthesis in Human Anatomy & Physiology

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