Question 1

Which of the following best explains why microbes bound to surfaces (such as in biofilms) have greater access to nutrients compared to planktonic (free-floating) cells?

Accepted Answer

Biofilms trap nutrients within a polysaccharide matrix, increasing local nutrient concentration.

Question 2

Which of the following is NOT a reason bacteria form biofilms?

Accepted Answer

To increase the rate of horizontal gene transfer.

Question 3

During biofilm formation, which stage involves the production of an adhesive matrix primarily composed of polysaccharides?

Accepted Answer

Colonization

Question 4

The signaling molecule cyclic di-Guanosine Monophosphate ($$c$$-$$di$$-$$GMP) is $$important in biofilm formation because:

Accepted Answer

It regulates the switch between motility and biofilm formation.

Question 5

Pseudomonas aeruginosa is particularly problematic in clinical settings because its biofilm:

Accepted Answer

Contains polysaccharides that increase pathogenicity and prevent antibiotic penetration.

Question 6

Which of the following medical conditions is NOT commonly associated with biofilm formation?

Accepted Answer

Influenza

Question 7

Why are biofilms more tolerant to antibiotics compared to planktonic cells?

Accepted Answer

The polysaccharide matrix limits antibiotic penetration and cells may be dormant.

Question 8

Quorum sensing allows bacteria to:

Accepted Answer

Assess their population density and coordinate group behaviors.

Question 9

Which molecule is typically used by bacteria as an autoinducer in quorum sensing?

Accepted Answer

Acyl homoserine lactone (AHL)

Question 10

Quorum sensing was first discovered as a mechanism regulating which process in Aliivibrio fischeri?

Accepted Answer

Bioluminescence

Question 11

Which of the following is a correct example of quorum sensing regulating virulence factors?

Accepted Answer

Toxin production in Escherichia coli O157:H7

Question 12

Antibiotics are best defined as:

Accepted Answer

Antimicrobials naturally produced by microbes that kill or inhibit bacterial growth.

Question 13

Which of the following is NOT a common target of antibiotics?

Accepted Answer

Mitochondria

Question 14

A microorganism is considered antibiotic resistant if it:

Accepted Answer

Can resist the effects of an antibiotic produced by another microbe.

Question 15

Which of the following is NOT a natural mechanism of antibiotic resistance?

Accepted Answer

Increased uptake of antibiotics

Question 16

The AcrAB-TolC efflux pump in Escherichia coli is upregulated under which condition?

Accepted Answer

When cells enter biofilm growth mode

Question 17

Methicillin-resistant Staphylococcus aureus (MRSA) is resistant to methicillin because:

Accepted Answer

It has a mecA gene that encodes a modified penicillin-binding protein.

Question 18

Persistence in bacterial populations refers to:

Accepted Answer

A subpopulation of genetically identical but dormant cells that are transiently tolerant to antibiotics.

Question 19

Which of the following best describes why persister cells survive antibiotic treatment?

Accepted Answer

They are dormant, so antibiotics targeting active processes are ineffective.

Question 20

In an industrial setting, biofilms can cause which of the following problems?

Accepted Answer

Accelerate corrosion of pipes and slow the flow of liquids.

8, 20, 7: Surfaces, Biofilms, Quorum Sensing, and Antibiotic Resistance in Microbiology

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