Question 1

Which of the following best describes an auxotrophic bacterial mutant?

Accepted Answer

A bacterium that requires additional nutrients because it cannot synthesize a specific compound due to a mutation.

Question 2

During bacterial conjugation, what is the primary role of the F factor?

Accepted Answer

It allows the bacterium to form a sex pilus and transfer DNA to another cell.

Question 3

Which experimental result would indicate that two bacterial genes are closely linked on the chromosome during a transformation experiment?

Accepted Answer

A high frequency of cotransformation for the two genes.

Question 4

In an interrupted mating experiment, which gene will be transferred to the F- cell first?

Accepted Answer

The gene closest to the integrated F factor.

Question 5

A bacterium that can take up free DNA from its environment is described as:

Accepted Answer

Competent

Question 6

Which of the following statements about Hfr cells is correct?

Accepted Answer

They have the F factor integrated into their chromosome and can transfer chromosomal genes at high frequency.

Question 7

What is the expected outcome when an F' cell conjugates with an F- cell?

Accepted Answer

The F- cell becomes F' and is partial diploid for some genes.

Question 8

Which process involves the transfer of bacterial genes by a bacteriophage?

Accepted Answer

Transduction

Question 9

In a generalized transduction experiment, which genes are most likely to be cotransduced?

Accepted Answer

Genes that are close together on the chromosome.

Question 10

A bacteriophage that can integrate its DNA into the host genome and remain dormant is called:

Accepted Answer

Temperate phage

Question 11

Which of the following best explains why cotransformation frequency is higher for genes that are close together?

Accepted Answer

They are more likely to be present on the same DNA fragment taken up by the recipient cell.

Question 12

Which of the following is a key step in the CRISPR-Cas bacterial immune system?

Accepted Answer

Integration of viral DNA fragments into the CRISPR array.

Question 13

A partial diploid (merozygote) in bacteria is produced when:

Accepted Answer

An F' plasmid carrying chromosomal genes is transferred to an F- cell.

Question 14

Which of the following equations correctly predicts the expected cotransformation frequency if two genes are transformed independently?

Accepted Answer

$$0.026 	imes 0.04 = 0.00104$$

Question 15

Which of the following is true about the lytic cycle of a bacteriophage?

Accepted Answer

The host cell is lysed, releasing new phage particles.

Question 16

In a gene mapping experiment using phage, what does the presence of recombinant plaques indicate?

Accepted Answer

Crossing over occurred between viral chromosomes.

Question 17

Which of the following best describes a minimal medium?

Accepted Answer

A medium containing only a carbon source, salts, and requiring bacteria to synthesize most compounds.

Question 18

Which of the following is NOT a method of gene transfer in bacteria?

Accepted Answer

Translation

Question 19

A student observes that after mixing two auxotrophic strains of E. coli, prototrophic colonies appear. What is the most likely explanation?

Accepted Answer

Genetic recombination between the two strains.

Question 20

Which of the following best explains why an F- cell does not become Hfr after conjugation with an Hfr cell?

Accepted Answer

The entire chromosome, including the integrated F factor, is rarely transferred during conjugation.

Bacterial and Viral Genetic Systems: Mechanisms and Mapping

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