Question 1

Which of the following best describes a biofilm?

Accepted Answer

A community of microorganisms attached to a surface and embedded in a self-produced extracellular matrix.

Question 2

What is the primary function of quorum sensing in biofilm formation?

Accepted Answer

To enable bacteria to detect cell density and coordinate gene expression for group behaviors.

Question 3

Which of the following is NOT an advantage of living in a biofilm compared to a planktonic state?

Accepted Answer

Faster growth rates for all cells in the biofilm.

Question 4

Dental caries (cavities) are primarily caused by which process in dental biofilms?

Accepted Answer

Fermentation of sugars by bacteria, leading to acid production and enamel demineralization.

Question 5

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

Accepted Answer

Antibiotics are often inactivated or poorly penetrate the EPS matrix, and many cells are metabolically slow.

Question 6

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

Accepted Answer

Slime on river rocks.

Question 7

What is the main role of extracellular DNA in a biofilm?

Accepted Answer

It is fundamental to the stability of the biofilm matrix.

Question 8

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

Accepted Answer

Biofilm bacteria are protected from immune cells and antibiotics by the EPS matrix.

Question 9

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

Accepted Answer

Rough surfaces provide increased surface area and protection from flow, aiding attachment.

Question 10

Which step in biofilm development is most directly regulated by quorum sensing?

Accepted Answer

Production of EPS and maturation of the biofilm.

Question 11

A mutant strain of Streptococcus mutans cannot produce glucans. What is the most likely consequence for dental biofilm formation?

Accepted Answer

The mutant will have impaired biofilm formation due to lack of EPS matrix.

Question 12

Which of the following equations best represents the process of acid production in dental biofilms?

Accepted Answer

$$	ext{Sucrose} \xrightarrow{	ext{fermentation}} 	ext{Lactic acid} + 	ext{other acids}$$

Question 13

Which of the following is a plausible reason why biofilms are implicated in chronic infections such as those seen in cystic fibrosis or on prosthetic joints?

Accepted Answer

Biofilms protect bacteria from antibiotics and immune attack, allowing persistent infection.

Question 14

Which of the following interventions could most directly disrupt biofilm formation on medical devices?

Accepted Answer

Coating the device with nanospikes to physically disrupt bacterial attachment.

Question 15

In the context of biofilms and Alzheimer’s disease, what is the hypothesized role of biofilms in the brain?

Accepted Answer

Biofilms may trigger inflammation by activating white blood cells, which then damage surrounding neural tissue.

Question 16

Which of the following best distinguishes a biofilm from a bacterial colony?

Accepted Answer

Biofilms are surface-attached communities in an EPS matrix with coordinated behaviors, while colonies are visible clonal masses on solid media.

Question 17

Which of the following is a key feature of the extracellular polymeric substance (EPS) in biofilms?

Accepted Answer

It contains polysaccharides, proteins, lipids, and extracellular DNA, providing structure and protection.

Question 18

Which of the following scenarios best illustrates the concept of 'persister cells' in a biofilm?

Accepted Answer

Metabolically slow cells within a biofilm that survive antibiotic treatment and can regrow the biofilm.

Question 19

Which of the following factors does NOT promote biofilm formation?

Accepted Answer

Presence of anti-adherent chemicals on the surface.

slides #7 -Biofilms: Structure, Formation, and Clinical Importance in Microbiology

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