Question 1

Which of the following best describes the main structural difference between Gram-positive and Gram-negative bacterial cell envelopes, as shown in the provided diagrams?

Accepted Answer

Gram-positive bacteria have a thick peptidoglycan layer and no outer membrane, while Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane containing LPS.

Question 2

Which component is unique to the outer membrane of Gram-negative bacteria and contributes to their increased resistance to certain antibiotics?

Accepted Answer

Lipopolysaccharides (LPS)

Question 3

Which of the following statements about archaeal membrane lipids is correct?

Accepted Answer

Archaeal membranes contain isoprenoid side chains linked by ether bonds.

Question 4

A patient is diagnosed with a bacterial infection. The Gram stain is positive, and the physician prescribes penicillin. What is the most likely target of this antibiotic?

Accepted Answer

The cross-linking of peptidoglycan in the cell wall

Question 5

Which of the following best explains why Gram-negative bacteria are generally more resistant to antibiotics than Gram-positive bacteria?

Accepted Answer

Their outer membrane acts as a barrier to many drugs and contains porins that regulate entry.

Question 6

Which of the following is a function of the S-layer found in some prokaryotes?

Accepted Answer

Protection against phagocytosis and acting as a molecular sieve

Question 7

Which of the following best describes the energy source for the rotation of the bacterial flagellum?

Accepted Answer

A proton (H$$^+) or $$sodium (Na$$^+) $$motive force across the membrane

Question 8

Which of the following is a key difference between the flagella of Bacteria and Archaea?

Accepted Answer

Bacterial flagella are hollow and assembled at the tip, while archaeal flagella are solid and assembled at the base.

Question 9

Which of the following best describes the role of the protein FtsZ in bacterial cell division?

Accepted Answer

It forms a ring at the cell center to guide septum formation during binary fission.

Question 10

A bacterium is observed to have flagella distributed all over its surface. What is the correct term for this arrangement?

Accepted Answer

Peritrichous

Question 11

Which of the following best explains why Mycobacterium species do not stain well with the Gram stain?

Accepted Answer

Their cell envelope contains mycolic acids and glycolipids that prevent dye penetration.

Question 12

Which of the following is a correct statement about the composition of archaeal membranes compared to bacterial membranes?

Accepted Answer

Archaeal membranes contain glycerol-1-phosphate backbones and isoprenoid chains linked by ether bonds.

Question 13

Which of the following best describes the function of ABC (ATP-Binding Cassette) transporters in prokaryotic cells?

Accepted Answer

They use the energy from ATP hydrolysis to transport nutrients against their concentration gradient.

Question 14

Which of the following is a micronutrient required by prokaryotes in trace amounts?

Accepted Answer

Zinc (Zn$$^{2+})$$

Question 15

During which phase of the bacterial growth curve is the generation time (doubling time) measured?

Accepted Answer

Log (exponential) phase

Question 16

Which of the following environmental factors does NOT directly affect prokaryotic cell growth?

Accepted Answer

Cell wall thickness

Question 17

Which protein is responsible for guiding the elongation of the peptidoglycan network during bacterial cell growth?

Accepted Answer

MreB

Question 18

A bacterium is found to grow optimally at 4$$^	ext{o}C. $$Which term best describes this organism?

Accepted Answer

Psychrophile

Question 19

Which of the following best describes the stationary phase of the bacterial growth curve?

Accepted Answer

Nutrients are depleted, waste accumulates, and cell division rate equals cell death rate.

Question 20

Which of the following is a correct description of the function of teichoic acids in Gram-positive bacteria?

Accepted Answer

They provide structural support and contribute to the negative charge of the cell wall.

The Prokaryote Cell Envelope and Growth: Structure, Function, and Clinical Relevance

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