Question 1

Which of the following best explains why Gram-positive bacteria retain the crystal violet stain during the Gram stain procedure?

Accepted Answer

Their thick peptidoglycan layer is dehydrated by alcohol, trapping the crystal violet-iodine complex.

Question 2

A patient is infected with a bacterium that is resistant to penicillin. Based on cell wall structure, which type of bacterium is most likely responsible?

Accepted Answer

Gram-negative bacteria, due to their outer membrane and low susceptibility to penicillin.

Question 3

Which of the following statements about the plasma membrane is correct?

Accepted Answer

It is a phospholipid bilayer with embedded proteins, some of which are glycoproteins and glycolipids.

Question 4

Which antimicrobial agent acts primarily by disrupting the bacterial plasma membrane, causing leakage of cell contents?

Accepted Answer

Polymyxin

Question 5

Why are mycoplasmas resistant to antibiotics that interfere with cell wall synthesis?

Accepted Answer

They lack a cell wall and have sterols in their plasma membrane.

Question 6

Which of the following inclusions is correctly matched with its function?

Accepted Answer

Metachromatic granules—phosphate reserves

Question 7

A bacterium is observed to survive boiling, desiccation, and exposure to radiation. Which structure is most likely responsible for this resistance?

Accepted Answer

Endospore

Question 8

Which of the following best describes the function of the nucleoid in a prokaryotic cell?

Accepted Answer

It contains the cell’s genetic information in a circular DNA molecule.

Question 9

Which of the following is a significant difference between prokaryotic and eukaryotic ribosomes?

Accepted Answer

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

Question 10

Which of the following best explains why acid-fast bacteria retain carbolfuchsin after acid-alcohol rinsing?

Accepted Answer

They have a waxy lipid (mycolic acid) bound to peptidoglycan.

Question 11

Which of the following is NOT a function of the prokaryotic cytoskeleton?

Accepted Answer

Photosynthesis

Question 12

Which of the following is true regarding the endosymbiotic theory?

Accepted Answer

Mitochondria and chloroplasts have circular DNA and 70S ribosomes, supporting their bacterial origin.

Question 13

Which of the following is a key difference between prokaryotic and eukaryotic flagella?

Accepted Answer

Eukaryotic flagella are composed of microtubules and move in a wavelike manner.

Question 14

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

Accepted Answer

Outer membrane containing lipopolysaccharide

Question 15

Which process allows a eukaryotic cell to engulf large particles by extending pseudopods?

Accepted Answer

Phagocytosis

Question 16

A bacterium is found to have magnetosomes. What is the most likely function of these structures?

Accepted Answer

Orientation along the Earth's magnetic field

Question 17

Which of the following best describes the function of group translocation in prokaryotes?

Accepted Answer

It chemically modifies a substance as it is transported into the cell.

Question 18

Which of the following is NOT a characteristic of eukaryotic plasma membranes compared to prokaryotic plasma membranes?

Accepted Answer

Presence of peptidoglycan

Question 19

Which of the following antibiotics specifically targets the 50S subunit of prokaryotic ribosomes, inhibiting protein synthesis?

Accepted Answer

Erythromycin

Question 20

Which of the following organelles is NOT associated with the Golgi complex and what does this suggest about its evolutionary origin?

Accepted Answer

Mitochondria; they likely originated from endosymbiotic bacteria.

Cell Structure and Function: Prokaryotic and Eukaryotic Cells

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