Q: Which of the following equations best represents the semiconservative nature of DNA replication?

$$\text{Parent DNA} \rightarrow \text{1 old strand} + \text{1 new strand}$$

Question 1

Which of the following best describes the structure of a typical bacterial chromosome?

Accepted Answer

A closed circular, double-helical DNA molecule located in the nucleoid

Question 2

Which mechanism of horizontal gene transfer requires a bacteriophage as a vector?

Accepted Answer

Transduction

Question 3

A laboratory strain of E. coli is treated with calcium chloride ($$\mathrm{$$CaCl_2$$}) $$and then exposed to free DNA. What process is being utilized to introduce new genetic material?

Accepted Answer

Transformation

Question 4

Which type of plasmid is responsible for encoding antibiotic resistance genes?

Accepted Answer

Resistance (R) plasmids

Question 5

In Frederick Griffith’s experiment with Streptococcus pneumoniae, what was the key finding that demonstrated transformation?

Accepted Answer

Live R strain mixed with heat-killed S strain killed the mice and live S strain was recovered

Question 6

Which of the following statements about plasmids is FALSE?

Accepted Answer

Plasmids are essential for bacterial survival under all conditions

Question 7

During bacterial conjugation, what is the role of the sex pilus?

Accepted Answer

It attaches the donor cell to the recipient cell to facilitate DNA transfer

Question 8

Which of the following best explains why an Hfr cell does NOT convert an F- cell into an F+ cell during conjugation?

Accepted Answer

The entire F plasmid is not transferred before the mating bridge breaks

Question 9

Which of the following is a real-world consequence of horizontal gene transfer among bacteria?

Accepted Answer

Development of antibiotic-resistant bacterial strains

Question 10

A bacterium that cannot synthesize arginine is called an auxotroph. After conjugation with an Hfr cell, the recipient can now synthesize arginine. What genetic event most likely occurred?

Accepted Answer

The recipient cell received the arginine synthesis genes from the donor's chromosome

Question 11

Which of the following best describes generalized transduction?

Accepted Answer

A bacteriophage transfers random fragments of bacterial DNA during the lytic cycle

Question 12

Which of the following equations best represents the semiconservative nature of DNA replication?

Accepted Answer

$$	ext{Parent DNA} ightarrow 	ext{1 old strand} + 	ext{1 new strand}$$

Question 13

Which of the following is a function of virulence plasmids?

Accepted Answer

They encode factors such as toxins, adhesins, and invasins that enhance pathogenicity

Question 14

A bacterium is exposed to a temperate phage, which integrates into its genome. What is the bacterium now called?

Accepted Answer

Lysogen

Question 15

Which of the following is required for bacterial transformation to occur?

Accepted Answer

Free DNA in the environment and a competent recipient

Question 16

Which of the following best explains why some bacteria can survive antibiotic treatment?

Accepted Answer

They have acquired resistance genes via horizontal gene transfer

Question 17

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

Accepted Answer

Generalized transduction transfers random DNA fragments; specialized transduction transfers specific DNA fragments

Question 18

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

Accepted Answer

Replication starts at the origin of transfer (oriT) and one strand of the plasmid is transferred to the recipient

Question 19

Which of the following bacteria is known for acquiring Shiga toxin genes via horizontal gene transfer, leading to severe disease outbreaks?

Accepted Answer

Escherichia coli O157:H7

Question 20

Which of the following is NOT a type of plasmid found in bacteria?

Accepted Answer

Lysogenic plasmid

Microbial Genetics: Mechanisms of Genetic Exchange in Bacteria

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