Question 1

Which of the following best describes the structure and function of the bacterial cytoplasmic membrane?

Accepted Answer

It is a selectively permeable phospholipid bilayer embedded with proteins, functioning as a permeability barrier, protein anchor, and site of energy conservation.

Question 2

Which of the following statements about Gram-positive and Gram-negative bacterial cell walls is CORRECT?

Accepted Answer

Gram-positive bacteria have a thick peptidoglycan layer and may contain teichoic acids, while Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane containing LPS.

Question 3

Which of the following best explains why penicillin is generally ineffective against Gram-negative bacteria?

Accepted Answer

The outer membrane of Gram-negative bacteria acts as a barrier, preventing penicillin from reaching the peptidoglycan layer.

Question 4

Which of the following is a unique feature of archaeal cytoplasmic membranes compared to bacterial membranes?

Accepted Answer

Archaeal membranes may contain ether-linked isoprenoid chains and can form monolayers.

Question 5

A scientist treats a bacterial culture with lysozyme. What is the most likely outcome for the cells?

Accepted Answer

The cells will lose their peptidoglycan layer and become protoplasts.

Question 6

Which of the following best describes the function of the proton motive force (pmf) in bacteria?

Accepted Answer

It is used to synthesize ATP from ADP and inorganic phosphate via ATP synthase.

Question 7

Which of the following is TRUE regarding the Gram stain procedure?

Accepted Answer

Gram-positive cells retain the crystal violet stain due to their thick peptidoglycan layer.

Question 8

Which of the following is a function of bacterial capsules?

Accepted Answer

They protect bacteria from phagocytosis and desiccation.

Question 9

Which of the following best describes the structure of peptidoglycan?

Accepted Answer

It is a polymer of N-acetylglucosamine and N-acetylmuramic acid cross-linked by short peptides.

Question 10

Which of the following is a distinguishing feature of acid-fast bacterial cell walls?

Accepted Answer

They contain a thick layer of mycolic acids and are resistant to standard Gram staining.

Question 11

Which of the following transport systems directly uses ATP hydrolysis to move substances across the membrane?

Accepted Answer

ABC (ATP-binding cassette) transporter

Question 12

A bacterium is found to lack a cell wall but survives due to the presence of sterols in its membrane. Which genus does it most likely belong to?

Accepted Answer

Mycoplasma

Question 13

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

Accepted Answer

S-layers are arrays of protein or glycoprotein subunits that can serve as the primary surface structure in Archaea.

Question 14

Which of the following best explains why Mycoplasma species are classified as Firmicutes despite lacking a cell wall?

Accepted Answer

Genomic studies show they are closely related to Gram-positive bacteria.

Question 15

Which of the following is a correct equation for the synthesis of ATP via the proton motive force?

Accepted Answer

$$\mathrm{ADP} + \mathrm{P_i} \rightarrow \mathrm{ATP}$$

Question 16

Which of the following is a function of bacterial fimbriae?

Accepted Answer

Attachment to surfaces and host tissues

Question 17

Which of the following is TRUE regarding the function of pili in bacteria?

Accepted Answer

They allow attachment and facilitate DNA exchange between cells.

Question 18

Which of the following best describes the role of lipopolysaccharide (LPS) in Gram-negative bacteria?

Accepted Answer

It forms the outer leaflet of the outer membrane and contributes to structural integrity and immune evasion.

Question 19

Which of the following is a correct description of group translocation in bacterial transport systems?

Accepted Answer

A substance is chemically modified as it is transported across the membrane, often using phosphoenolpyruvate (PEP) as the phosphate donor.

Microbial Cell Structure and Function: Bacterial Cell Envelopes and Membranes

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