Question 1

Which of the following best describes a key structural difference between bacterial and archaeal cytoplasmic membranes?

Accepted Answer

Bacterial membranes have ester linkages in their phospholipids, while archaeal membranes have ether linkages.

Question 2

A researcher isolates a prokaryote with a cell wall that lacks peptidoglycan but contains pseudopeptidoglycan. Which domain does this organism most likely belong to?

Accepted Answer

Archaea

Question 3

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

Accepted Answer

It acts as a selective barrier and contributes to the pathogenicity of the bacterium.

Question 4

A patient is infected with a Gram-negative bacterium. Which component of the cell envelope is most likely to trigger a strong immune response, potentially leading to septic shock?

Accepted Answer

Lipopolysaccharide (LPS)

Question 5

Which of the following cell surface structures is primarily involved in bacterial attachment to surfaces and biofilm formation?

Accepted Answer

Fimbriae

Question 6

A bacterium is observed to have a thick, gelatinous layer outside its cell wall that helps it evade phagocytosis. What is this structure called?

Accepted Answer

Capsule

Question 7

Which of the following inclusions allows aquatic prokaryotes to regulate their buoyancy?

Accepted Answer

Gas vesicles

Question 8

During the sporulation cycle, which structure forms first to protect the developing endospore's genetic material?

Accepted Answer

Core wall

Question 9

Which of the following statements best explains why endospores are more resistant to environmental stresses than vegetative cells?

Accepted Answer

Endospores contain dipicolinic acid and calcium ions, which stabilize DNA and proteins.

Question 10

A microbiologist discovers a prokaryote with a crystalline protein layer outside its cell wall. This structure is most likely a(n):

Accepted Answer

S-layer

Question 11

Which of the following best describes the main function of polyhydroxyalkanoate (PHA) granules in prokaryotic cells?

Accepted Answer

They store carbon and energy for later use.

Question 12

A Gram-positive bacterium is exposed to lysozyme, which hydrolyzes the glycosidic bonds in peptidoglycan. What is the most likely outcome?

Accepted Answer

The cell will lyse due to osmotic pressure.

Question 13

Which of the following equations best represents the chemical structure of a phospholipid found in bacterial membranes?

Accepted Answer

$$\mathrm{Glycerol} + 2\ \mathrm{Fatty\ acids} + \mathrm{Phosphate}$$

Question 14

Which of the following is a key difference between the cell walls of Gram-positive and Gram-negative bacteria?

Accepted Answer

Gram-positive bacteria have a thick peptidoglycan layer, while Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane.

Question 15

A bacterium stores excess phosphate in the form of polyphosphate granules. Which of the following best describes the role of these inclusions?

Accepted Answer

They act as a reserve of phosphate for nucleic acid and ATP synthesis.

Question 16

Which of the following best explains why archaeal membranes are more stable in extreme environments compared to bacterial membranes?

Accepted Answer

Archaeal membranes contain ether-linked isoprenoid chains, which are more chemically stable.

Question 17

During the sporulation cycle, which of the following events occurs after the formation of the forespore but before the release of the mature endospore?

Accepted Answer

Engulfment of the forespore by the mother cell

Question 18

A clinical sample contains rod-shaped cells that survive boiling and are resistant to desiccation. Which structure is most likely responsible for this resistance?

Accepted Answer

Endospore

Question 19

Which of the following best describes the function of magnetosomes in certain prokaryotes?

Accepted Answer

They allow the cell to orient along magnetic fields.

Question 20

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

Accepted Answer

The cell will lose its ability to maintain selective permeability and may lyse.

Microbial Cell Structure and Function: Study Notes

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