Question 1

Which of the following statements best describes the semiconservative model of DNA replication?

Accepted Answer

Each new DNA molecule consists of one parental strand and one newly synthesized strand.

Question 2

A mutation changes the DNA sequence from $$	ext{AAA} to$$ $$	ext{AAG}$$, but both codons code for lysine. What type of mutation is this?

Accepted Answer

Silent mutation

Question 3

Which enzyme is responsible for unzipping the DNA double helix during replication?

Accepted Answer

DNA helicase

Question 4

In prokaryotic cells, what is the function of the F plasmid?

Accepted Answer

It carries instructions for conjugation and formation of sex pili.

Question 5

Which of the following best explains why erythromycin selectively targets bacterial cells without harming human cells?

Accepted Answer

It binds to the 70S ribosome found in bacteria, which is structurally different from the 80S ribosome in humans.

Question 6

A scientist exposes bacteria to UV light, which causes the formation of thymine dimers. What type of mutagen is UV light?

Accepted Answer

Nonionizing radiation

Question 7

Which of the following is a key difference between eukaryotic and prokaryotic transcription?

Accepted Answer

Eukaryotic mRNA is processed by capping, polyadenylation, and splicing before translation.

Question 8

A bacterial cell is exposed to a chemical that causes the insertion of a single nucleotide into a gene. What is the most likely result?

Accepted Answer

A frameshift mutation

Question 9

Which of the following best describes the function of tRNA during translation?

Accepted Answer

It delivers specific amino acids to the ribosome based on the codon-anticodon interaction.

Question 10

Which process is illustrated by the following scenario: A bacterium acquires a gene for toxin production from a virus that previously infected another bacterium?

Accepted Answer

Transduction

Question 11

Which of the following is true about the lac operon in E. coli?

Accepted Answer

It is an inducible operon activated in the presence of lactose.

Question 12

Which of the following best describes a missense mutation?

Accepted Answer

A mutation that changes one amino acid in the protein sequence.

Question 13

Which of the following is a function of DNA methylation in bacteria?

Accepted Answer

It plays a role in the initiation of DNA replication, gene expression, and protection against viral infection.

Question 14

A scientist discovers a segment of DNA that can move from one location to another within a genome, sometimes carrying antibiotic resistance genes. What is this segment called?

Accepted Answer

Transposon

Question 15

Which of the following is a real-world consequence of horizontal gene transfer via conjugation?

Accepted Answer

Spread of antibiotic resistance among bacterial populations

Question 16

Which of the following best describes the role of regulatory RNAs such as miRNA in eukaryotic cells?

Accepted Answer

They bind to mRNA to prevent translation or degrade the mRNA.

Question 17

A bacterial cell is able to take up free DNA from its environment and incorporate it into its genome. This process is known as:

Accepted Answer

Transformation

Question 18

Which of the following best explains why frameshift mutations are often more severe than point mutations?

Accepted Answer

They result in the insertion or deletion of nucleotides, altering the reading frame and potentially changing every amino acid downstream.

Question 19

Which of the following is a characteristic of an inducible operon?

Accepted Answer

It is activated by the presence of a substrate, such as lactose.

Question 20

Which of the following is a direct result of a nonsense mutation in a gene?

Accepted Answer

A truncated, usually nonfunctional protein due to an early stop codon

Microbial Genetics: Structure, Function, Mutation, and Genetic Transfer

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