Question 1

Which of the following statements best describes the primary structural difference between prokaryotic and eukaryotic cells?

Accepted Answer

Prokaryotic cells lack a membrane-bound nucleus, while eukaryotic cells possess one.

Question 2

Which component of the bacterial cell envelope is primarily responsible for protecting the cell from osmotic shock in a hypotonic environment?

Accepted Answer

Cell wall

Question 3

Penicillin is most effective against which type of bacteria, and why?

Accepted Answer

Gram-positive bacteria, because they have a thick peptidoglycan layer exposed to the environment.

Question 4

Which of the following best describes the chemical structure of peptidoglycan?

Accepted Answer

Repeating units of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) cross-linked by short peptides

Question 5

A bacterium is found to have a thick peptidoglycan layer, teichoic acids, and no outer membrane. Which Gram reaction will it show and why?

Accepted Answer

Gram-positive, because the thick peptidoglycan retains the crystal violet stain.

Question 6

Which component of the Gram-negative cell wall is responsible for its toxicity and can trigger a strong immune response in humans?

Accepted Answer

Lipid A portion of lipopolysaccharide (LPS)

Question 7

Why are Gram-negative bacteria generally more resistant to antibiotics like penicillin compared to Gram-positive bacteria?

Accepted Answer

Their outer membrane acts as a permeability barrier, preventing antibiotics from reaching the peptidoglycan layer.

Question 8

Which of the following best describes the function of the bacterial glycocalyx when present as a capsule?

Accepted Answer

Protection from phagocytosis by host immune cells

Question 9

A bacterium with peritrichous flagella would be best described as having:

Accepted Answer

Flagella distributed all around its surface

Question 10

Which structure is primarily responsible for the transfer of genetic material between bacterial cells during conjugation?

Accepted Answer

Pilus

Question 11

Which of the following statements about bacterial ribosomes is correct?

Accepted Answer

Prokaryotic ribosomes are 70S, while eukaryotic ribosomes are 80S.

Question 12

Which of the following best explains why Mycobacterium tuberculosis is difficult to stain using the Gram stain?

Accepted Answer

Its cell wall contains mycolic acid, which is hydrophobic and resists standard stains.

Question 13

Which of the following is NOT a function of the bacterial cell wall?

Accepted Answer

Site of protein synthesis

Question 14

A patient is infected with a bacterium that survives boiling and can remain dormant for years. Which structure is most likely responsible for this resistance?

Accepted Answer

Endospore

Question 15

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

Accepted Answer

Movement toward or away from chemical stimuli using flagella

Question 16

Which of the following is a correct statement about plasmids in bacteria?

Accepted Answer

They are extra-chromosomal DNA that can encode antibiotic resistance.

Question 17

Which enzyme found in human saliva and tears specifically breaks the bond between NAG and NAM in peptidoglycan?

Accepted Answer

Lysozyme

Question 18

Which of the following storage inclusions would you expect to find in Azotobacter species?

Accepted Answer

Polyhydroxybutyrate granules

Question 19

A bacterium is observed to have a loosely organized, gelatinous outer layer that helps it adhere to surfaces. What is this structure called?

Accepted Answer

Slime layer

Question 20

Which of the following best explains why Mycoplasma species are resistant to antibiotics that target cell wall synthesis?

Accepted Answer

They lack a cell wall entirely.

Prokaryotic Cell Structure and Function: Microbiology Study Guide

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