Question 1

Which of the following best describes the main advantage of biofilm formation for bacteria in a medical context?

Accepted Answer

Biofilms provide a protective matrix that increases resistance to antibiotics and immune responses.

Question 2

During which stage of the biofilm life cycle are bacteria most easily removed by rinsing or light cleaning?

Accepted Answer

Initial Attachment (Reversible)

Question 3

Dental plaque is an example of a biofilm. Which of the following statements about dental plaque is correct?

Accepted Answer

It is a biofilm that can lead to cavities and gum disease if not removed.

Question 4

Which of the following is NOT a typical role of cells within a mature biofilm?

Accepted Answer

All cells in a biofilm perform the same function regardless of location

Question 5

Quorum sensing in bacteria involves which of the following processes?

Accepted Answer

The use of chemical signals to coordinate group behaviors based on cell density

Question 6

Which chemical signal is primarily used by Gram-negative bacteria for quorum sensing?

Accepted Answer

Acyl-homoserine lactones (AHLs)

Question 7

A patient with cystic fibrosis develops a chronic lung infection with Pseudomonas aeruginosa. Which feature of P. aeruginosa biofilms makes this infection particularly difficult to treat?

Accepted Answer

The biofilm matrix protects bacteria from antibiotics and immune cells.

Question 8

Which of the following best explains why synthetic fabrics like polyester are more prone to 'permastink' compared to natural fibers like cotton?

Accepted Answer

Polyester traps oils and provides microscopic spaces for biofilm formation, making odors persistent.

Question 9

Which of the following strategies is an example of quorum quenching?

Accepted Answer

Adding enzymes that degrade signaling molecules to disrupt bacterial communication

Question 10

In the context of biofilm treatment, why is a combination of physical disruption and enzymatic 'slime breakers' often necessary?

Accepted Answer

The biofilm matrix must be broken down to expose bacteria to antibiotics and allow for effective removal.

Question 11

Which equation best represents the positive feedback loop in quorum sensing, where $$S is $$the concentration of signaling molecules and $$N is $$the number of bacteria?

Accepted Answer

$$\frac{dS}{dt} = \alpha N + \beta S$$

Question 12

Which of the following is a real-world example of a beneficial biofilm in the human body?

Accepted Answer

Lactobacilli biofilms in the vagina preventing growth of harmful microbes

Question 13

A researcher wants to disrupt the communication between Gram-positive bacteria in a biofilm. Which type of signaling molecule should they target?

Accepted Answer

Autoinducing peptides (AIPs)

Question 14

Which of the following best describes the function of persister cells in a biofilm?

Accepted Answer

They enter a dormant state, making them highly resistant to antibiotics.

Question 15

Why are most antibiotics less effective against bacteria in the Maturation II (3D structure) stage of a biofilm?

Accepted Answer

The thick EPS matrix limits antibiotic penetration and creates a protective environment.

Question 16

Which of the following is a correct sequence of the biofilm life cycle?

Accepted Answer

Initial attachment → Irreversible adhesion → Maturation I → Maturation II → Dispersion

Question 17

A hospital is experiencing frequent infections related to catheters. Which of the following is the most likely explanation based on biofilm biology?

Accepted Answer

Biofilms on catheters protect bacteria from antibiotics, making infections persistent.

Question 18

Which of the following is a function of the PQS system in Pseudomonas aeruginosa quorum sensing?

Accepted Answer

Links the Las and Rhl systems and helps regulate biofilm formation and iron uptake

Question 19

A laundry detergent claims to eliminate 'permastink' by breaking down biofilms in synthetic fabrics. Which ingredient would most likely contribute to this effect?

Accepted Answer

Enzymes that degrade the extracellular polymeric substances (EPS)

Question 20

Which of the following best explains the 're-stink' effect in synthetic athletic wear?

Accepted Answer

Residual biofilm bacteria are reactivated by heat and sweat, rapidly producing odor again.

lec 23:Biofilms: Structure, Function, and Clinical Relevance

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