Question 1

Which of the following statements correctly describes the composition of pseudomurein found in some archaeal cell walls?

Accepted Answer

It is composed of N-acetylglucosamine and N-acetylalosaminuronic acid linked by $$\beta(1,3)$$ bonds.

Question 2

Which feature makes pseudomurein in archaeal cell walls resistant to lysozyme?

Accepted Answer

Presence of $$\beta(1,3)$$ glycosidic bonds between N-acetylglucosamine and N-acetylalosaminuronic acid.

Question 3

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

Accepted Answer

Gram-negative bacteria have an outer membrane containing LPS and a thin peptidoglycan layer.

Question 4

Endotoxin, a toxic component of Gram-negative bacteria, is associated with which part of the cell wall?

Accepted Answer

Lipid A portion of lipopolysaccharide (LPS)

Question 5

A researcher isolates a microorganism with a cell wall composed of N-acetylglucosamine and N-acetylalosaminuronic acid, and it is lysozyme-insensitive. What type of organism is most likely being studied?

Accepted Answer

Archaeon with pseudomurein cell wall

Question 6

Which cell surface structure enables bacteria to adhere to surfaces and form pellicles?

Accepted Answer

Fimbriae

Question 7

Which of the following is NOT a function of gas vesicles in planktonic microorganisms?

Accepted Answer

Enable movement toward light (phototaxis)

Question 8

Endospores are highly differentiated cells found in some bacteria. Which of the following is NOT a property of endospores?

Accepted Answer

They are present in all Gram-negative bacteria.

Question 9

Which of the following cell inclusions is used by bacteria for magnetic orientation?

Accepted Answer

Magnetosomes

Question 10

A bacterium is observed to move toward a source of oxygen. This behavior is best described as:

Accepted Answer

Aerotaxis

Question 11

Which of the following correctly describes the process and outcome of meiosis in eukaryotic cells?

Accepted Answer

Chromosome number is halved, resulting in four haploid gametes.

Question 12

Which organelle is responsible for respiration and oxidative phosphorylation in eukaryotic cells?

Accepted Answer

Mitochondrion

Question 13

According to the endosymbiotic theory, which evidence supports the idea that mitochondria and chloroplasts originated from ancient prokaryotic cells?

Accepted Answer

They contain circular DNA and their own ribosomes.

Question 14

Which of the following is a storage polymer used by bacteria to store carbon?

Accepted Answer

Poly-$$\beta-$$hydroxybutyric acid (PHB)

Question 15

A Gram-negative bacterium is exposed to a chemical that disrupts the LPS layer. Which of the following consequences is most likely?

Accepted Answer

Loss of endotoxin activity

Question 16

Which of the following structures is found in eukaryotic cells but NOT in prokaryotic cells?

Accepted Answer

Nucleus

Question 17

Which of the following is true regarding S-layers in Archaea?

Accepted Answer

They are the most common cell wall type in Archaea.

Question 18

Which of the following best explains why Gram-negative bacteria are generally more resistant to certain antibiotics than Gram-positive bacteria?

Accepted Answer

Gram-negative bacteria possess an outer membrane that acts as a barrier to many antibiotics.

Question 19

A scientist observes a cell with circular DNA, its own ribosomes, and a double membrane. Which organelle is most likely being observed?

Accepted Answer

Mitochondrion

L3 Microbial Cell Structure and Function: Cell Walls, Membranes, and Surface Structures

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