Question 1

Which of the following is NOT a possible fate for DNA that enters a bacterial cell during horizontal gene transfer?

Accepted Answer

It is incorporated as an autonomous genetic element, such as a plasmid.

Question 2

Fredrick Griffith's experiment with Streptococcus pneumoniae demonstrated which genetic transfer process?

Accepted Answer

Transformation

Question 3

Which of the following best describes a merodiploid bacterial strain?

Accepted Answer

A strain carrying two copies of a particular chromosomal segment, one on the chromosome and one on a plasmid or phage.

Question 4

During bacterial transformation, which protein is primarily responsible for mediating homologous recombination?

Accepted Answer

RecA protein

Question 5

In the context of conjugation, what is the function of the tra genes found on the F plasmid?

Accepted Answer

They encode transfer functions necessary for plasmid mobilization.

Question 6

Which of the following statements about generalized transduction is correct?

Accepted Answer

Any portion of the host genome can be packaged inside the virion and transferred.

Question 7

A bacterium is exposed to a temperate phage that lysogenizes the cell. Which of the following is a possible outcome of phage conversion?

Accepted Answer

The host cell acquires immunity to further infection by the same phage.

Question 8

Which mechanism of horizontal gene transfer involves cell-to-cell contact and a plasmid-encoded system?

Accepted Answer

Conjugation

Question 9

What is the role of oriT in the F plasmid?

Accepted Answer

It is the origin of transfer during conjugation.

Question 10

Why does an Hfr x F- mating not yield two Hfr cells?

Accepted Answer

Because only a portion of the integrated F plasmid is transferred, not the whole chromosome.

Question 11

Which of the following best explains the concept of complementation in bacterial genetics?

Accepted Answer

A mutant phenotype is restored by a functional wild-type gene supplied on a plasmid or phage.

Question 12

In the detection of genetic recombination using Trp- and Trp+ cells, what outcome indicates successful recombination?

Accepted Answer

Formation of colonies on agar medium lacking tryptophan.

Question 13

Which of the following is TRUE regarding specialized transduction?

Accepted Answer

DNA from a specific region of the host chromosome is integrated into the virus genome and transferred.

Question 14

What is the primary barrier to horizontal gene transfer in bacteria as depicted in CRISPR-Cas systems?

Accepted Answer

CRISPR-Cas system specifically recognizes foreign DNA and degrades it.

Question 15

Which of the following statements about F' plasmids is correct?

Accepted Answer

F' plasmids are formed when an integrated F plasmid excises and captures some chromosomal genes.

Question 16

Which equation best represents the probability $$P of a $$recipient cell acquiring a new trait via transformation, given the concentration of free DNA $$[DNA]$$ and the competence factor $$C$$?

Accepted Answer

$$P = C 	imes [DNA]$$

Question 17

Which of the following is a real-world consequence of phage conversion in bacteria?

Accepted Answer

Production of toxins resulting in a pathogenic strain.

Question 18

In conjugation, what is the difference between an F+ cell and an Hfr cell?

Accepted Answer

F+ cells possess a nonintegrated F plasmid, while Hfr cells have the F plasmid integrated into the chromosome.

Question 19

Which of the following mechanisms is regulated by quorum sensing in Bacillus subtilis and Vibrio cholerae?

Accepted Answer

Competence for transformation

Question 20

A researcher wants to increase the efficiency of transformation in a bacterial population. Which strategy would most likely be effective?

Accepted Answer

Increase the expression of pili and competence factors.

Mechanisms of Genetic Variation in Prokaryotes: Horizontal Gene Transfer and Recombination

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