Question 1

Which of the following best describes the central dogma of molecular biology?

Accepted Answer

DNA is transcribed into RNA, which is then translated into protein.

Question 2

A mutation that results in the insertion of a single nucleotide into a gene sequence is most likely to cause which of the following?

Accepted Answer

A frameshift mutation

Question 3

Which enzyme is responsible for unwinding the DNA double helix during replication in bacteria?

Accepted Answer

Helicase

Question 4

In the lac operon of E. coli, what happens when lactose is present?

Accepted Answer

The repressor is inactivated by an inducer, allowing transcription.

Question 5

Which of the following is a function of plasmids in bacteria?

Accepted Answer

They may carry genes for antibiotic resistance.

Question 6

A nonsense mutation is best described as:

Accepted Answer

A mutation that results in a stop codon.

Question 7

Which of the following statements about bacterial DNA replication is correct?

Accepted Answer

Replication is bidirectional and both daughter cells receive a copy of DNA.

Question 8

Which of the following best explains why UV radiation can be mutagenic?

Accepted Answer

It causes the formation of thymine dimers, disrupting DNA replication.

Question 9

In the context of the Ames test, what does a high reversion rate indicate?

Accepted Answer

The substance is highly mutagenic.

Question 10

Which of the following is true about horizontal gene transfer in bacteria?

Accepted Answer

It involves the transfer of genes between cells of the same generation.

Question 11

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

Accepted Answer

It transports amino acids to the ribosome and matches them to the mRNA codon.

Question 12

A bacterial cell is exposed to a chemical that causes the replacement of a cytosine with a thymine in a gene. This is an example of:

Accepted Answer

Base substitution (point mutation)

Question 13

Which of the following is a characteristic of repressible operons?

Accepted Answer

They are usually on but can be turned off by a corepressor.

Question 14

Which of the following enzymes is responsible for joining Okazaki fragments during DNA replication?

Accepted Answer

DNA ligase

Question 15

A bacterial cell that has acquired a new trait by taking up naked DNA from its environment has undergone:

Accepted Answer

Transformation

Question 16

Which of the following is NOT a possible outcome of a mutation in a bacterial gene?

Accepted Answer

Increased accuracy of DNA replication

Question 17

Which of the following statements about the genetic code is correct?

Accepted Answer

There are 64 possible codons and 20 amino acids.

Question 18

Which of the following best describes the role of the operator in an operon?

Accepted Answer

It is the site where repressors can bind to regulate transcription.

Question 19

Which of the following is a real-world consequence of horizontal gene transfer among bacteria?

Accepted Answer

Spread of antibiotic resistance genes in hospitals

Question 20

Which of the following is a correct statement about the proofreading function of DNA polymerase?

Accepted Answer

It ensures high accuracy by correcting mismatched bases.

Microbial Genetics: Structure, Function, and Mechanisms

Study Guide - Practice Questions