Question 1

Which of the following best describes the structure of DNA as depicted in the first image?

Accepted Answer

A double helix with antiparallel strands, where cytosine pairs with guanine and thymine pairs with adenine via hydrogen bonds.

Question 2

Given an organism with 18% thymine in its DNA, what is the G+C content of its genome?

Accepted Answer

$$G + C = 64\%$$

Question 3

Which enzyme is responsible for joining Okazaki fragments on the lagging strand during DNA replication?

Accepted Answer

DNA ligase

Question 4

What is the main difference between the leading and lagging strands during DNA replication?

Accepted Answer

The leading strand is synthesized continuously, while the lagging strand is synthesized in short fragments.

Question 5

Which type of plasmid carries genes for antibiotic resistance?

Accepted Answer

R plasmid

Question 6

Which of the following best describes the process shown in the third image?

Accepted Answer

Conjugation, where DNA is transferred from a donor to a recipient cell via a pilus.

Question 7

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

Accepted Answer

Regulation of gene expression and protection against restriction enzymes.

Question 8

Which of the following statements about mRNA is correct?

Accepted Answer

mRNA carries the genetic code from DNA to the ribosome for protein synthesis.

Question 9

What is the effect of a frameshift mutation on a protein-coding gene?

Accepted Answer

It alters the reading frame, potentially changing every amino acid downstream of the mutation.

Question 10

Which of the following best describes the Ames test, as shown in the second image?

Accepted Answer

A test that uses Salmonella to detect mutagenic chemicals by measuring the reversion rate to histidine prototrophy.

Question 11

Which of the following is true about generalized transduction?

Accepted Answer

A bacteriophage transfers random segments of bacterial DNA to another bacterium.

Question 12

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

Accepted Answer

Prokaryotes can couple transcription and translation, while eukaryotes cannot.

Question 13

Which of the following best describes an auxotroph?

Accepted Answer

A mutant organism that requires a specific additional nutrient that the wild type does not.

Question 14

Which of the following is a base analog mutagen?

Accepted Answer

5-bromouracil

Question 15

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

Accepted Answer

It is normally off and is induced in the presence of lactose.

Question 16

Which of the following is a function of small interfering RNA (siRNA) in bacteria?

Accepted Answer

Gene silencing by binding to complementary mRNA and promoting its degradation.

Question 17

Which of the following is a characteristic of an F plasmid?

Accepted Answer

It carries genes for conjugation (tra genes) and can transfer itself to other bacteria.

Question 18

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

Accepted Answer

Uptake of naked DNA from the environment by a competent cell.

Question 19

Which of the following is true about the repair of pyrimidine dimers?

Accepted Answer

Light repair uses photolyase to break the dimer, while dark repair uses endonuclease to remove the damaged DNA segment.

Microbial Genetics: Structure, Function, and Genetic Variation

Study Guide - Practice Questions