Question 1

Which of the following best describes the main function of the cytoplasmic membrane in prokaryotic cells?

Accepted Answer

It acts as a selective permeability barrier, allowing nutrients in and waste out.

Question 2

A researcher isolates a microorganism with a cell wall composed of pseudomurein. Which of the following statements about this organism is most likely true?

Accepted Answer

It is an archaeon, likely a methanogen.

Question 3

Which component of the Gram-negative bacterial cell envelope is responsible for the toxic effects associated with infections?

Accepted Answer

Lipid A of the lipopolysaccharide (LPS) layer

Question 4

A patient is infected with a bacterium that is resistant to penicillin and lysozyme. The cell wall contains alternating N-acetylglucosamine and N-acetyltalosaminuronic acid. What is the most likely explanation for this resistance?

Accepted Answer

The bacterium is an archaeon with a pseudomurein cell wall.

Question 5

Which of the following equations best represents the relationship between the rate of flagellar rotation ($$\omega) $$and the strength of the proton motive force ($$\Delta p) in $$bacteria?

Accepted Answer

$$\omega = k \cdot \Delta p$$

Question 6

Which of the following best explains why Mycoplasma species are resistant to antibiotics that target cell wall synthesis?

Accepted Answer

They lack a cell wall and only have a cytoplasmic membrane.

Question 7

A Gram-negative bacterium is exposed to a chemical that disrupts its outer membrane. Which of the following is the most likely immediate consequence?

Accepted Answer

Loss of selective permeability and increased sensitivity to toxic compounds.

Question 8

Which of the following structures is primarily responsible for the attachment of bacteria to surfaces and the formation of biofilms?

Accepted Answer

Fimbriae

Question 9

A bacterium is observed to move toward a higher concentration of glucose. This behavior is best described as:

Accepted Answer

Chemotaxis

Question 10

Which of the following statements about endospores is correct?

Accepted Answer

They are dormant, highly resistant cells formed by some Gram-positive bacteria.

Question 11

Which of the following best distinguishes Gram-positive from Gram-negative bacteria?

Accepted Answer

Gram-positive bacteria have teichoic acids in their cell wall.

Question 12

A scientist is studying a microorganism with an S-layer as its main cell wall component. Which group does this organism most likely belong to?

Accepted Answer

Archaea

Question 13

Which of the following is a function of the capsule in bacteria?

Accepted Answer

Protection against phagocytosis and desiccation

Question 14

Which of the following best explains why penicillin is effective against most Gram-positive bacteria but not against most Gram-negative bacteria?

Accepted Answer

Gram-negative bacteria have an outer membrane that restricts penicillin entry.

Question 15

A bacterium with electrically conductive pili is most likely to be involved in which of the following processes?

Accepted Answer

Electron transfer in biofilms or microbial fuel cells

Question 16

Which of the following is true regarding the structure of archaeal membranes compared to bacterial membranes?

Accepted Answer

Archaeal membranes often contain ether-linked lipids, while bacterial membranes have ester-linked lipids.

Question 17

A Gram-negative bacterium is exposed to a hypotonic solution after its cell wall is enzymatically removed. What is the most likely outcome?

Accepted Answer

The cell will lyse due to osmotic pressure.

Question 18

Which of the following best describes the role of the proton motive force ($$\Delta p) in $$bacterial cells?

Accepted Answer

It drives the rotation of flagella and ATP synthesis.

Question 19

Which of the following statements about the glycan tetrapeptide in bacterial cell walls is correct?

Accepted Answer

It is composed of alternating N-acetylglucosamine and N-acetylmuramic acid residues.

Question 20

A hospital-acquired infection is traced to a biofilm on a catheter. Which of the following structures most likely contributed to the initial attachment of bacteria to the catheter surface?

Accepted Answer

Fimbriae

Microbial Cell Structure and Function: Study Notes

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