Question 1

Which of the following best describes horizontal gene transfer in bacteria?

Accepted Answer

The transfer of genetic material between cells of the same generation

Question 2

Which mechanism of horizontal gene transfer involves the uptake of 'naked' DNA from the environment by a bacterial cell?

Accepted Answer

Transformation

Question 3

A researcher is studying a bacterial strain that can metabolize an unusual sugar not commonly found in its environment. Which genetic element is most likely responsible for this new metabolic capability?

Accepted Answer

Dissimilation plasmid

Question 4

Which of the following statements about transposons is correct?

Accepted Answer

Transposons are segments of DNA that can move from one region of DNA to another

Question 5

During bacterial conjugation, what is the role of the F (fertility) plasmid?

Accepted Answer

It encodes for sex pili and enables the transfer of plasmid DNA to a recipient cell

Question 6

Which of the following best explains why Bacillus anthracis is highly virulent?

Accepted Answer

It possesses two plasmids encoding a capsule and a tripartite exotoxin complex

Question 7

A laboratory experiment uses electroporation to introduce a plasmid into E. coli. Which of the following best describes the principle behind electroporation?

Accepted Answer

Applying a high-voltage pulse creates temporary pores in the cell membrane, allowing DNA to enter

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 specific genes near the prophage site

Question 9

In Griffith's experiment, which combination of bacterial strains led to the death of the mouse and the recovery of encapsulated bacteria from its tissues?

Accepted Answer

Living nonencapsulated and heat-killed encapsulated bacteria

Question 10

Which of the following best describes the function of the protective antigen (PA) component of the Bacillus anthracis exotoxin?

Accepted Answer

It binds to host cell receptors and facilitates entry of other toxin components

Question 11

A patient presents with severe nausea and vomiting after eating rice left at room temperature overnight. Which bacterial species and toxin are most likely responsible?

Accepted Answer

Bacillus cereus, cereulide

Question 12

Which of the following is a real-world application of Bacillus thuringiensis (Bt) toxins?

Accepted Answer

Bt toxins are used as environmentally friendly insecticides in agriculture

Question 13

Which of the following best explains why genetically modified (GM) crops expressing Bt toxin genes are effective against specific insect pests?

Accepted Answer

Bt toxins require specific receptors in the insect gut to be effective

Question 14

Which of the following equations best represents the probability $P$ of a recipient cell acquiring a new gene via transformation, given the concentration of extracellular DNA $[DNA]$, the competence factor $C$, and a proportionality constant $k$?

Accepted Answer

$P = k \cdot [DNA] \cdot C$

Question 15

Which of the following is NOT a typical feature of R (resistance) plasmids?

Accepted Answer

They encode for proteins needed for the catabolism of unusual sugars

Question 16

A scientist observes that a bacterial strain has acquired resistance to multiple antibiotics after exposure to another strain. Which genetic element is most likely responsible for this rapid acquisition?

Accepted Answer

A resistance plasmid (R factor)

Question 17

Which of the following best explains why the mortality rate of inhalational anthrax is so high, even with treatment?

Accepted Answer

The tripartite exotoxin complex rapidly disrupts host immune and cellular functions

Question 18

Which of the following statements about natural transformation in bacteria is correct?

Accepted Answer

Competence allows bacteria to actively transport environmental DNA into the cytoplasm

Question 19

Which of the following is a plausible consequence of horizontal gene transfer for bacterial evolution?

Accepted Answer

It enables rapid acquisition of new traits such as antibiotic resistance or metabolic capabilities

Question 20

A researcher is studying a bacterial population exposed to a new antibiotic. After several generations, some bacteria survive and are found to carry a plasmid. Which process most likely led to the spread of antibiotic resistance in this population?

Accepted Answer

Horizontal gene transfer via conjugation

Horizontal Gene Transfer in Bacteria: Mechanisms and Genetic Elements

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