Question 1

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

Accepted Answer

It acts as a selective permeability barrier, controlling the transport of nutrients and waste.

Question 2

Which structural feature distinguishes the cytoplasmic membrane of Archaea from that of Bacteria?

Accepted Answer

Archaeal membranes can be monolayers with isoprenoid chains, while bacterial membranes are always bilayers with fatty acids.

Question 3

A scientist isolates a cell envelope with a thick peptidoglycan layer and teichoic acids. Which type of cell is this most likely from?

Accepted Answer

Gram-positive bacterium

Question 4

Which of the following is TRUE regarding the peptide cross-linking in peptidoglycan of Gram-negative bacteria?

Accepted Answer

Cross-linking occurs between DAP and D-alanine residues.

Question 5

Which component of the Gram-negative outer membrane is responsible for its toxic effects in humans?

Accepted Answer

Lipid A of lipopolysaccharide (LPS)

Question 6

Which of the following statements about pseudomurein in Archaea is correct?

Accepted Answer

It contains N-acetyltalosaminuronic acid (NAT) and is insensitive to lysozyme.

Question 7

Which of the following best explains why some Archaea can survive in extreme environments such as hydrothermal vents?

Accepted Answer

Their cytoplasmic membranes may be monolayers with isoprenoid chains, providing increased stability.

Question 8

Which of the following is NOT a function of bacterial capsules and slime layers?

Accepted Answer

Serving as the main permeability barrier of the cell

Question 9

A bacterium is observed to form a pellicle on the surface of a liquid culture. Which structure is most likely responsible for this behavior?

Accepted Answer

Pili

Question 10

Which of the following statements about endospores is FALSE?

Accepted Answer

Endospores are a form of active cell division and growth.

Question 11

Which of the following best describes the process of endospore germination?

Accepted Answer

It involves activation, germination, and outgrowth upon nutrient availability.

Question 12

Which of the following is a strengthening agent found in bacterial cytoplasmic membranes?

Accepted Answer

Hopanoid

Question 13

Which of the following correctly matches the cell envelope structure to the organism?

Accepted Answer

Gram-negative bacteria: thin peptidoglycan, outer membrane, lipopolysaccharide

Question 14

Which of the following is TRUE about the glycan backbone of peptidoglycan?

Accepted Answer

It is composed of alternating units of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM).

Question 15

Which of the following structures is NOT considered part of the bacterial outer membrane?

Accepted Answer

Capsule

Question 16

A patient is infected with a bacterium that is highly resistant to dehydration and forms biofilms on medical devices. Which structure is most likely contributing to these properties?

Accepted Answer

Capsule or slime layer

Question 17

Which of the following statements about S-layers is correct?

Accepted Answer

S-layers are paracrystalline protein or glycoprotein shells that can be the outermost layer of the cell envelope.

Question 18

Which of the following is a function of small acid-soluble spore proteins (SASPs) in bacterial endospores?

Accepted Answer

They bind and protect DNA and serve as a carbon and energy source during outgrowth.

Question 19

Which of the following best explains why lysozyme is effective against bacterial cell walls but not against pseudomurein?

Accepted Answer

Lysozyme cleaves glycosidic bonds between NAG and NAM, which are not present in pseudomurein.

Question 20

Which of the following is a correct sequence of events in the sporulation cycle of Bacillus subtilis?

Accepted Answer

Asymmetric cell division, forespore formation, engulfment by mother cell

Microbial Cell Structure: Cell Membranes and Cell Walls in Prokaryotes

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