Question 1

Which of the following best describes the process of bacterial transformation?

Accepted Answer

A bacterial cell takes up free DNA released from another cell into its own cytoplasm.

Question 2

Which mechanism of horizontal gene transfer in bacteria requires cell-to-cell contact and is often mediated by a plasmid?

Accepted Answer

Conjugation

Question 3

During generalized transduction, which type of DNA is packaged into the phage particle?

Accepted Answer

Random fragments of host bacterial DNA

Question 4

What is the role of RecA protein in homologous recombination in bacteria?

Accepted Answer

It mediates strand invasion and facilitates exchange between homologous DNA sequences.

Question 5

Which of the following is NOT a requirement for a bacterial cell to be competent for transformation?

Accepted Answer

Ability to package DNA into phage particles

Question 6

In specialized transduction, which DNA is transferred to the recipient cell?

Accepted Answer

Specific regions of host DNA adjacent to the integrated viral genome

Question 7

Which equation best represents the process of homologous recombination between two DNA molecules?

Accepted Answer

$$A + B \rightarrow AB^*$$

Question 8

A researcher wants to transfer antibiotic resistance genes from one bacterial species to another distantly related species. Which horizontal gene transfer mechanism is most likely to succeed?

Accepted Answer

Conjugation

Question 9

Which of the following statements about CRISPR/Cas9 in prokaryotes is TRUE?

Accepted Answer

It provides adaptive immunity by targeting specific nucleic acids from invading viruses.

Question 10

Which of the following is a plausible fate for DNA transferred into a bacterial cell via horizontal gene transfer?

Accepted Answer

The DNA replicates independently as a plasmid.

Question 11

Which protein is essential for the development of cross-strand exchange during homologous recombination?

Accepted Answer

RecA

Question 12

A bacterial cell is exposed to DNA fragments from a lysed cell in its environment. What process allows the cell to acquire new genetic traits from these fragments?

Accepted Answer

Transformation

Question 13

Which of the following best explains why not all genes acquired by horizontal gene transfer are retained in bacteria and archaea?

Accepted Answer

Mechanisms exist to maintain genomic integrity and selectively retain beneficial genes.

Question 14

Which of the following is a difference between generalized and specialized transduction?

Accepted Answer

Generalized transduction transfers random host DNA, while specialized transduction transfers specific DNA adjacent to the prophage.

Question 15

Which of the following is a function of the SSB (single-stranded binding) protein during homologous recombination?

Accepted Answer

It binds and stabilizes single-stranded DNA to prevent secondary structure formation.

Question 16

In the context of CRISPR/Cas9, what is the role of the spacer DNA integrated into the host genome?

Accepted Answer

It serves as a genetic memory of past viral infections.

Question 17

Which of the following equations represents the process of DNA nicking by an endonuclease during recombination?

Accepted Answer

$$DNA_{ds} \xrightarrow{endonuclease} DNA_{ss} + DNA_{ss}$$

Question 18

Which of the following statements about horizontal gene transfer in Archaea is correct?

Accepted Answer

Transformation, transduction, and conjugation have all been observed in Archaea.

Question 19

A bacterial cell receives DNA via conjugation. What must occur for the transferred DNA to be stably maintained in the recipient cell?

Accepted Answer

The DNA must either replicate independently or recombine with the host chromosome.

Question 20

Which of the following best describes the role of quorum sensing in bacterial competence for transformation?

Accepted Answer

It regulates the expression of genes required for DNA uptake.

Chapter 9

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