Question 1

Which of the following best describes the sequence of events in biofilm formation as depicted in the provided images?

Accepted Answer

Planktonic cell → Attached cell → Microcolony → Biofilm → Detached cell

Question 2

Which cellular structure is primarily responsible for the initial movement of bacteria toward a surface during biofilm formation?

Accepted Answer

Flagella

Question 3

What is the main function of exopolysaccharide production during biofilm development?

Accepted Answer

To stabilize the three-dimensional structure of the biofilm

Question 4

Which of the following statements about gene expression in biofilm-associated cells is correct?

Accepted Answer

Gene expression profiles in biofilm-associated cells are distinct from planktonic cells.

Question 5

In the context of biofilm formation, what is the role of acyl-homoserine lactones (acyl-HSLs)?

Accepted Answer

They mediate intercellular communication and regulate biofilm architecture.

Question 6

Why are biofilm-associated bacteria generally more resistant to antibiotics than planktonic bacteria?

Accepted Answer

They are protected by decreased diffusion, slower growth rates, and exopolysaccharide barriers.

Question 7

Which of the following best explains why bacteria in nutrient-poor environments preferentially attach to nutritive surfaces like chitin?

Accepted Answer

Chitin induces expression of specific attachment and degradation genes, maximizing nutrient access.

Question 8

What is the significance of horizontal gene transfer in biofilms?

Accepted Answer

It accelerates the spread of antibiotic resistance and virulence factors.

Question 9

Which of the following is a plausible reason for the detachment of cells from a mature biofilm?

Accepted Answer

Degradation of exopolysaccharide by polysaccharide lyase during starvation

Question 10

In a multispecies biofilm, how do bacteria typically organize themselves?

Accepted Answer

According to who can survive best in each microenvironment and based on symbiotic relationships

Question 11

Which of the following equations best represents the relationship between the rate of horizontal gene transfer ($$R_{HGT}) $$and the density of cells ($$D) in a $$biofilm?

Accepted Answer

$$R_{HGT} = k \cdot D$$

Question 12

Which of the following is NOT a function of exopolysaccharide in biofilms?

Accepted Answer

Increasing flagellar motility

Question 13

A mutant strain of Pseudomonas aeruginosa lacks the ability to produce acyl-HSLs. What is the most likely phenotype regarding its biofilm structure?

Accepted Answer

It forms biofilms with closely packed cells that are easily disrupted.

Question 14

Which of the following best describes the role of type IV pili in biofilm formation?

Accepted Answer

They generate force for initial surface approach and facilitate movement along the surface.

Question 15

Which of the following is a likely consequence of the negative regulation of flagellum synthesis by the alternative sigma factor $$\$$sigma^{22}$$ in Pseudomonas aeruginosa?

Accepted Answer

Stabilization of the biofilm structure due to increased alginate production

Question 16

Which of the following best explains why biofilm-associated cells may exhibit zero population growth in mature biofilms?

Accepted Answer

Spatial constraints and exopolysaccharide encasement impede cell division.

Question 17

Which of the following is a real-world example of lethal interspecies bacterial communication in biofilms?

Accepted Answer

Production of bacteriocins that kill closely related species

Question 18

Which of the following best describes the effect of nutrient-rich versus nutrient-poor environments on bacterial surface attachment?

Accepted Answer

In nutrient-poor environments, bacteria attach preferentially to nutritive surfaces like chitin.

Question 19

Which of the following is a plausible adaptive advantage of storing energy in exopolysaccharide within a biofilm?

Accepted Answer

It provides a digestible scaffold that can be used as an energy source during nutrient scarcity.

Biofilm Formation and Microbial Communities: Structure, Function, and Genetic Regulation

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