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 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?

Accepted Answer

Helicase

Question 4

In the lac operon, what happens when lactose is present and glucose is absent?

Accepted Answer

cAMP levels increase, CAP binds to the promoter, and the operon is highly expressed.

Question 5

Which of the following is a consequence of a nonsense mutation?

Accepted Answer

A premature stop codon is introduced, truncating the protein.

Question 6

Which process describes the transfer of genetic material from one bacterium to another via a bacteriophage?

Accepted Answer

Transduction

Question 7

What is the role of DNA ligase during DNA replication?

Accepted Answer

It joins Okazaki fragments on the lagging strand.

Question 8

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

Accepted Answer

Frameshift mutations alter the reading frame, changing every amino acid downstream.

Question 9

A gene is normally expressed, but when a corepressor is present, the gene is turned off. This describes which type of operon?

Accepted Answer

Repressible operon

Question 10

Which of the following statements about bacterial chromosomes is correct?

Accepted Answer

They are typically single, circular DNA molecules.

Question 11

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

Accepted Answer

It brings specific amino acids to the ribosome based on codon-anticodon pairing.

Question 12

Which of the following is true regarding the genetic code?

Accepted Answer

It is degenerate, meaning multiple codons can code for the same amino acid.

Question 13

Which of the following is a real-world consequence of bacterial gene alteration?

Accepted Answer

Development of antibiotic resistance in pathogens.

Question 14

Which enzyme is responsible for synthesizing a short RNA primer during DNA replication?

Accepted Answer

Primase

Question 15

A scientist exposes bacteria to UV light, resulting in the formation of thymine dimers. Which repair mechanism is most likely to fix this damage?

Accepted Answer

Nucleotide excision repair

Question 16

Which of the following best describes the process of transformation in bacteria?

Accepted Answer

Uptake of naked DNA from the environment by a recipient cell

Question 17

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

Accepted Answer

They often carry genes for antibiotic resistance.

Question 18

A mutation changes the codon UAU (tyrosine) to UAA. What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 19

Which of the following best explains why the Ames test uses liver extract?

Accepted Answer

Many chemicals are not directly mutagenic but are converted to mutagens by liver enzymes.

Question 20

Which of the following statements about transposons is correct?

Accepted Answer

They are mobile genetic elements that can move within and between DNA molecules.

Microbial Genetics: Structure, Function, and Regulation

Study Guide - Practice Questions