Question 1

Which of the following best describes the main function of the bacterial cell wall?

Accepted Answer

It provides tensile strength and protection against mechanical and osmotic stress.

Question 2

A scientist observes a bacterium that stains purple with Gram stain and contains teichoic acids in its cell wall. Which of the following statements is most accurate about this bacterium?

Accepted Answer

It is Gram-positive and has a thick peptidoglycan layer.

Question 3

Which of the following is a unique feature of bacterial plasma membranes compared to eukaryotic plasma membranes?

Accepted Answer

Presence of hopanoids instead of cholesterol for membrane stability.

Question 4

Which of the following best explains why bacteria with a higher surface area-to-volume ratio are more efficient at nutrient uptake?

Accepted Answer

They can increase the rate of diffusion of molecules across the membrane.

Question 5

A bacterium is placed in a hypotonic solution and treated with lysozyme. What is the most likely outcome?

Accepted Answer

The cell will lyse due to osmotic pressure.

Question 6

Which of the following is a function of the S-layer in bacteria?

Accepted Answer

It protects the cell from ion and pH fluctuations.

Question 7

Which of the following best describes group translocation in bacteria?

Accepted Answer

It involves the chemical modification of a molecule as it is transported into the cell.

Question 8

Which of the following structures is responsible for the motility of spirochetes?

Accepted Answer

Axial filaments (endoflagella) located within the periplasmic space.

Question 9

Which of the following statements about bacterial ribosomes is correct?

Accepted Answer

They are 70S in size and found in the cytoplasm and attached to the plasma membrane.

Question 10

A bacterium is found to survive in the absence of a cell wall in an isotonic environment. Which of the following best explains this observation?

Accepted Answer

The plasma membrane is more resistant to osmotic pressure.

Question 11

Which of the following is a correct description of the structure of peptidoglycan?

Accepted Answer

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

Question 12

Which of the following best describes the function of bacterial plasmids?

Accepted Answer

They carry genes that can confer a selective advantage, such as antibiotic resistance.

Question 13

Which of the following is a property of bacterial endospores that contributes to their resistance to environmental stresses?

Accepted Answer

Presence of calcium-dipicolinic acid (Ca-DPA) and small, acid-soluble, DNA-binding proteins (SASPs).

Question 14

Which of the following best describes the process of chemotaxis in bacteria?

Accepted Answer

Movement toward or away from a chemical gradient by altering the frequency of runs and tumbles.

Question 15

Which of the following is a function of extracellular vesicles (EVs) in bacteria?

Accepted Answer

They transfer genetic information and toxins between cells.

Question 16

Which of the following best describes the role of siderophores in bacterial iron uptake?

Accepted Answer

They are small organic molecules that bind ferric iron (Fe3+) and facilitate its transport into the cell.

Question 17

Which of the following is true regarding the arrangement of cocci in Staphylococcus aureus?

Accepted Answer

They form grape-like clusters due to division in random planes.

Question 18

Which of the following is a distinguishing feature of Gram-negative bacteria compared to Gram-positive bacteria?

Accepted Answer

Presence of an outer membrane containing lipopolysaccharides (LPS).

Question 19

Which of the following best describes the function of bacterial capsules?

Accepted Answer

They protect bacteria from phagocytosis and desiccation.

Question 20

Which of the following is a correct statement about the bacterial nucleoid?

Accepted Answer

It contains a single, usually circular, double-stranded DNA molecule.

Bacterial Cell Structure and Function: Study Notes for Microbiology

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