Question 1

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

Accepted Answer

Lipid A of lipopolysaccharide (LPS)

Question 2

A scientist isolates a microorganism with a cell wall composed of pseudomurein containing $\beta$-1,3 glycosidic bonds and only L-amino acids. Which domain does this organism most likely belong to?

Accepted Answer

Archaea

Question 3

Which structure is found only in Gram-positive bacteria and contributes to cell wall rigidity and ion regulation?

Accepted Answer

Teichoic acids

Question 4

A patient is infected with a bacterium that forms endospores and survives extreme heat. Which genus is most likely responsible?

Accepted Answer

Bacillus

Question 5

Which of the following best describes the arrangement of phospholipids in a bacterial cytoplasmic membrane?

Accepted Answer

Hydrophilic heads face outward, hydrophobic tails face inward

Question 6

Why are bacterial cell walls resistant to osmotic lysis?

Accepted Answer

Covalent peptide cross-linking in peptidoglycan

Question 7

Which of the following is NOT a function of the cytoplasmic membrane in bacteria?

Accepted Answer

Peptidoglycan synthesis

Question 8

A Gram-negative bacterium is exposed to lysozyme. What is the expected outcome?

Accepted Answer

Cell lysis due to breakdown of peptidoglycan

Question 9

Which cell surface structure is primarily responsible for bacterial conjugation (DNA transfer)?

Accepted Answer

Sex pili

Question 10

A microorganism is observed to move toward a light source. Which type of taxis is this?

Accepted Answer

Phototaxis

Question 11

Which of the following is a major difference between bacterial and archaeal cytoplasmic membranes?

Accepted Answer

Bacteria have ester-linked fatty acids; Archaea have ether-linked isoprenoids

Question 12

Which structure allows bacteria to control their buoyancy and optimize access to light and nutrients?

Accepted Answer

Gas vesicles

Question 13

Which of the following statements about endosymbiotic theory is correct?

Accepted Answer

Chloroplasts evolved from cyanobacteria

Question 14

Which cell inclusion is responsible for magnetotaxis in bacteria?

Accepted Answer

Magnetosomes

Question 15

A bacterium with a thick peptidoglycan layer and no outer membrane is most likely:

Accepted Answer

Gram-positive

Question 16

Which of the following is unique to Gram-negative bacteria?

Accepted Answer

Outer membrane with LPS

Question 17

Which arrangement of flagella would you expect to find in Salmonella species?

Accepted Answer

Peritrichous

Question 18

Which of the following is NOT a function of capsules in bacteria?

Accepted Answer

Provide motility

Question 19

Which of the following statements about endospores is FALSE?

Accepted Answer

Endospores are found in Gram-negative bacteria

Question 20

Which enzyme breaks the $\beta$-1,4 glycosidic bonds in bacterial peptidoglycan, leading to cell lysis?

Accepted Answer

Lysozyme

Microbial Cell Structure and Function: Study Guide

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