Question 1

Which molecular marker is currently used as the primary basis for assigning organisms into the three domains of life: Bacteria, Archaea, and Eukarya?

Accepted Answer

16S rRNA gene sequences

Question 2

A Gram-positive bacterium is observed under the microscope with a chain-like arrangement of round cells. Which term best describes this arrangement?

Accepted Answer

Streptococcus

Question 3

Which of the following is NOT a typical advantage for bacteria living in a biofilm?

Accepted Answer

Increased predation by amoeba and other eukaryotic microbes

Question 4

Which of the following best describes the initial step in biofilm formation?

Accepted Answer

Free-floating cells attach to a surface

Question 5

A patient with a prosthetic heart valve develops a persistent infection. Which property of bacterial biofilms most likely contributes to the difficulty in treating this infection?

Accepted Answer

Biofilms confer increased resistance to antibiotics

Question 6

Which of the following statements about biofilms is TRUE?

Accepted Answer

In biofilms, there is often metabolic cooperation among bacteria

Question 7

Which bacterial structure is primarily responsible for motility in planktonic cells?

Accepted Answer

Flagellum

Question 8

A laboratory uses crystal violet staining to detect biofilm formation. What does the dye bind to in the biofilm?

Accepted Answer

Extracellular polysaccharides in the matrix

Question 9

Which of the following best explains why sari cloth filtration reduces cholera cases in rural Bangladesh?

Accepted Answer

The cloth traps Vibrio bacteria attached to marine snow particles

Question 10

Which phase in the bacterial life cycle is associated with the formation of fruiting bodies in myxobacteria?

Accepted Answer

Starvation and aggregation

Question 11

Which of the following is a medically relevant example of a biofilm?

Accepted Answer

Dental plaque leading to caries

Question 12

Which of the following cell shapes is described as 'curved rod'?

Accepted Answer

Vibrio

Question 13

Which of the following is a distinguishing feature of Actinomycetes compared to Myxobacteria?

Accepted Answer

Actinomycetes form aerial mycelia and spores

Question 14

A researcher observes a bacterial sample with the following arrangement: a grouping of four cocci arranged in a square. What is this arrangement called?

Accepted Answer

Tetrad

Question 15

Which of the following best describes the function of bacterial endospores?

Accepted Answer

Enable survival under extreme environmental conditions

Question 16

Which of the following is a correct statement about the composition of a bacterial capsule versus a biofilm matrix?

Accepted Answer

Capsules are tightly bound to individual cells, while biofilm matrices are diffuse and can be washed away

Question 17

Which of the following equations best describes the exponential phase of bacterial growth?

Accepted Answer

$$N_t = N_0$ e$$^{\mu t}$$

Question 18

Which of the following is a real-world consequence of biofilm formation in water systems?

Accepted Answer

Biofilms can harbor pathogens like Legionella, leading to diseases such as Legionnaire’s disease

Question 19

Which of the following best explains why bacteria in biofilms are more resistant to antibiotics than planktonic cells?

Accepted Answer

The extracellular matrix limits antibiotic penetration and creates microenvironments

Question 20

Which of the following is a benefit of biofilms in the human body?

Accepted Answer

Biofilms in the intestinal tract aid in digestion and protect against pathogens

Prokaryotes: Structure, Classification, and Biofilms

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