Question 1

Which of the following best explains why the cytoplasmic membrane is an effective barrier to ions and polar molecules?

Accepted Answer

The hydrophobic core of the phospholipid bilayer blocks ions and polar molecules.

Question 2

A bacterium is found to have a thick peptidoglycan layer, teichoic acids, and no outer membrane. Which of the following is most likely true about this organism?

Accepted Answer

It is Gram-positive and will stain purple in a Gram stain.

Question 3

Which component of the Gram-negative outer membrane is responsible for its endotoxin activity?

Accepted Answer

Lipid A

Question 4

Which of the following statements about archaeal cell walls is correct?

Accepted Answer

Methanogens may have pseudomurein with β-1,3 bonds.

Question 5

A patient is infected with a bacterium that resists phagocytosis and forms biofilms on medical devices. Which structure is most likely responsible for these properties?

Accepted Answer

Capsule

Question 6

Which of the following best describes the function of Type IV pili?

Accepted Answer

Motility via twitching and surface attachment

Question 7

Which of the following is a unique feature of Gram-negative bacteria?

Accepted Answer

Outer membrane containing lipopolysaccharide (LPS)

Question 8

A scientist isolates a microbe with ether-linked isoprenoid chains in its membrane. Which domain does this organism most likely belong to?

Accepted Answer

Archaea

Question 9

Which of the following best explains why penicillin is ineffective against most Archaea?

Accepted Answer

Archaea lack peptidoglycan in their cell walls.

Question 10

Which of the following structures is responsible for the buoyancy of aquatic bacteria, allowing them to optimize access to light and nutrients?

Accepted Answer

Gas vesicles

Question 11

A Gram-positive bacterium is exposed to lysozyme. What is the most likely outcome?

Accepted Answer

The cell wall is degraded, leading to osmotic lysis.

Question 12

Which of the following best describes the arrangement and Gram reaction of Staphylococcus?

Accepted Answer

Gram-positive cocci in clusters

Question 13

Which of the following is a key difference between endospores and fungal spores?

Accepted Answer

Endospores are for survival; fungal spores are for reproduction.

Question 14

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

Accepted Answer

Peptidoglycan synthesis

Question 15

Which of the following best describes the evidence supporting the endosymbiotic theory for the origin of mitochondria?

Accepted Answer

Mitochondria have circular DNA and bacterial-like ribosomes.

Question 16

Which of the following is the correct formula for the glycosidic bond found in bacterial peptidoglycan?

Accepted Answer

$$\beta-1$$,4 glycosidic bond

Question 17

Which of the following is a function of magnetosomes in bacteria?

Accepted Answer

Magnetotaxis (orientation to magnetic fields)

Question 18

A bacterium moves toward a nutrient source by alternating runs and tumbles. This behavior is best described as:

Accepted Answer

Chemotaxis

Question 19

Which of the following is true about the arrangement of flagella in Salmonella?

Accepted Answer

Peritrichous

Question 20

Which of the following is a correct statement about the function of teichoic acids?

Accepted Answer

They are found in Gram-positive bacteria and contribute to cell wall stability.

Microbial Cell Structure and Function: Study Guide

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