Question 1

Which of the following best explains why bacteria are particularly useful for genetic analysis?

Accepted Answer

They have haploid genomes, short generation times, and can produce large numbers of progeny.

Question 2

A bacterial strain that can grow on minimal medium but not on medium lacking leucine is best described as:

Accepted Answer

An auxotroph for leucine

Question 3

Which of the following statements about plasmids is FALSE?

Accepted Answer

All plasmids replicate independently of the bacterial chromosome.

Question 4

During bacterial conjugation, what is the role of the relaxosome?

Accepted Answer

It binds to the origin of transfer (oriT) and nicks one strand of the F factor DNA.

Question 5

In an interrupted mating experiment, the order of gene transfer is determined by:

Accepted Answer

The time at which each gene first appears in exconjugants.

Question 6

Which of the following best describes the outcome of an Hfr × F− conjugation?

Accepted Answer

The recipient cell remains F− but may acquire one or more donor alleles by homologous recombination.

Question 7

A bacterium that has acquired a segment of donor DNA via transformation is called a:

Accepted Answer

Transformant

Question 8

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

Accepted Answer

Generalized transduction can transfer any bacterial gene, while specialized transduction transfers only genes adjacent to the prophage integration site.

Question 9

Which of the following equations best represents the relationship between cotransduction frequency and gene distance?

Accepted Answer

$$f_{cotransduction} \propto \frac{1}{d}$$

Question 10

A researcher observes that a genomic island in a bacterial genome has a much higher G-C content than the rest of the genome. What is the most likely explanation?

Accepted Answer

The region was acquired by lateral gene transfer from a distantly related species.

Question 11

Which of the following best describes the process of rolling circle replication during bacterial conjugation?

Accepted Answer

One DNA strand is nicked and transferred to the recipient, while the donor synthesizes a replacement strand.

Question 12

Which of the following is a real-world consequence of lateral gene transfer in bacteria?

Accepted Answer

Acquisition of antibiotic resistance genes, leading to the emergence of multidrug-resistant pathogens.

Question 13

In a cotransduction experiment, which result would indicate that two genes are very close together on the bacterial chromosome?

Accepted Answer

A high frequency of cotransduction.

Question 14

Which of the following is TRUE regarding F′ (F prime) plasmids?

Accepted Answer

They carry F factor genes plus a segment of bacterial chromosomal DNA.

Question 15

Which of the following best describes the lysogenic cycle of a temperate bacteriophage?

Accepted Answer

The phage integrates its DNA into the host chromosome and remains dormant until triggered.

Question 16

A bacterium is resistant to streptomycin due to an R plasmid. In a conjugation experiment, which medium would you use to select for exconjugants?

Accepted Answer

Medium containing streptomycin

Question 17

Which of the following is a direct application of time-of-entry mapping in bacterial genetics?

Accepted Answer

Estimating the relative distances between genes based on the timing of their transfer during conjugation.

Question 18

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

Accepted Answer

Binary fission

Question 19

Which of the following best explains why multiple Hfr strains are needed to construct a complete genetic map of E. coli?

Accepted Answer

Each Hfr strain transfers genes in only one direction from its unique integration site.

Genetic Analysis and Mapping in Bacteria and Bacteriophages

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