Q: Which equation best represents the fermentation process leading to acid production in dental biofilms?

$$\text{Sucrose} \xrightarrow{\text{Strep. mutans}} \text{Glucose polymer (biofilm)} + \text{Fructose (inside cell)}$$

Question 1

Which of the following best describes a biofilm?

Accepted Answer

A structured community of bacterial cells enclosed in a self-produced extracellular polymeric substance (EPS) and adherent to a surface

Question 2

Which of the following is NOT a common location for biofilm formation in medical settings?

Accepted Answer

Red blood cells

Question 3

What is the primary function of the extracellular polymeric substance (EPS) in a biofilm?

Accepted Answer

To protect bacteria from antibiotics, toxins, and immune cells

Question 4

Which process allows bacteria in a biofilm to coordinate gene expression based on cell density?

Accepted Answer

Quorum sensing

Question 5

Why are bacteria in biofilms generally more resistant to antibiotics than planktonic bacteria?

Accepted Answer

The EPS matrix limits antibiotic penetration and facilitates persister cell formation

Question 6

Which of the following is a real-world consequence of biofilm formation on medical devices?

Accepted Answer

Chronic infections such as urinary tract infections and endocarditis

Question 7

What role does extracellular DNA play in biofilm stability?

Accepted Answer

It is fundamental to the structural stability of the biofilm matrix

Question 8

Which of the following best explains why rough surfaces promote biofilm formation?

Accepted Answer

They provide increased surface area and protection from flow

Question 9

A patient develops a chronic infection after receiving a urinary catheter. Which property of biofilms most likely contributes to the persistence of this infection?

Accepted Answer

Biofilms prevent immune cells from engulfing and killing bacteria

Question 10

Which of the following is a key step in the development of dental caries due to biofilm formation?

Accepted Answer

Fermentation of sucrose by Streptococcus mutans leading to acid production

Question 11

Which equation best represents the fermentation process leading to acid production in dental biofilms?

Accepted Answer

$$	ext{Sucrose} \xrightarrow{	ext{Strep. mutans}} 	ext{Glucose polymer (biofilm)} + 	ext{Fructose (inside cell)}$$

Question 12

Which of the following is a plausible strategy for controlling biofilm formation on medical devices?

Accepted Answer

Coating devices with nanospikes to physically disrupt bacterial attachment

Question 13

How does quorum sensing contribute to the formation and maintenance of biofilms?

Accepted Answer

By triggering gene expression changes once a critical cell density is reached

Question 14

Which of the following best explains why biofilms are implicated in the development of Alzheimer’s disease?

Accepted Answer

Biofilms activate immune cells, which are unable to clear the bacteria and instead damage surrounding neural tissue

Question 15

Which of the following is a key difference between planktonic and sessile (biofilm) bacterial cells?

Accepted Answer

Sessile cells are embedded in EPS and function as a community, while planktonic cells are free-floating

Question 16

Which of the following factors does NOT promote biofilm formation?

Accepted Answer

Presence of anti-adherent chemicals

Question 17

A mutant strain of Pseudomonas aeruginosa lacks the gene for glucosyltransferase. What is the most likely consequence for biofilm formation?

Accepted Answer

The mutant forms normal biofilms but is more sensitive to antibiotics due to reduced glucan production

Question 18

Which of the following best explains why biofilm-associated infections are often chronic and difficult to eradicate?

Accepted Answer

Biofilms shield bacteria from antibiotics and immune responses, allowing persistent infection

Question 19

Which of the following is a real-world example of a device-related biofilm infection?

Accepted Answer

Urinary catheter-associated infection

Question 20

Which of the following is a plausible multi-step approach to controlling dental plaque biofilms?

Accepted Answer

Targeting Streptococcus mutans with a vaccine and disrupting quorum sensing

Biofilms: Structure, Formation, and Clinical Significance in Microbiology

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