Question 1

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

Accepted Answer

Gram-negative bacteria possess an outer membrane containing lipopolysaccharide (LPS) that acts as a barrier to many antibiotics.

Question 2

A laboratory technician stains a bacterial sample and observes pink/red rod-shaped cells and blue cocci under the microscope after performing a Ziehl-Neelsen acid-fast stain. Which of the following is the most accurate interpretation?

Accepted Answer

The sample contains acid-fast rods (likely Mycobacterium) and non-acid-fast cocci.

Question 3

Which of the following structures is primarily responsible for the selective permeability of the bacterial plasma membrane?

Accepted Answer

Phospholipid bilayer with embedded proteins

Question 4

A patient is diagnosed with a urinary tract infection caused by Proteus species. Which structure is most likely involved in the bacteria's ability to colonize and move within the urinary tract?

Accepted Answer

Fimbriae and flagella

Question 5

Which of the following best describes the function of bacterial endospores?

Accepted Answer

They allow bacteria to survive harsh environmental conditions such as heat, radiation, and desiccation.

Question 6

Which component of the Gram-negative bacterial cell wall is considered an endotoxin and can trigger a strong immune response in humans?

Accepted Answer

Lipid A of lipopolysaccharide (LPS)

Question 7

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

Accepted Answer

Phototaxis

Question 8

Which of the following statements about facilitated diffusion and active transport in bacteria is correct?

Accepted Answer

Active transport moves substances against their concentration gradient and requires energy.

Question 9

A bacterial cell is placed in a hypertonic solution. What is the most likely outcome?

Accepted Answer

Water will flow out of the cell, causing plasmolysis.

Question 10

Which of the following best explains why Streptococcus pneumoniae with a capsule is more virulent than non-capsulated strains?

Accepted Answer

The capsule enables the bacterium to evade phagocytosis by host immune cells.

Question 11

Which of the following is a distinguishing feature of the cell wall of Gram-positive bacteria?

Accepted Answer

Thick peptidoglycan layer with teichoic acids

Question 12

Which of the following best describes the genetic material in most bacterial cells?

Accepted Answer

A single circular double-stranded DNA molecule located in the nucleoid region

Question 13

A laboratory identifies a bacterial strain as E. coli O157:H7. The 'O' antigen refers to which cell structure?

Accepted Answer

O polysaccharide of lipopolysaccharide (LPS)

Question 14

Which of the following is NOT a function of the bacterial plasma membrane?

Accepted Answer

Site of protein synthesis

Question 15

Which of the following best describes the arrangement and function of bacterial flagella?

Accepted Answer

Flagella are composed of a filament, hook, and basal body, and are responsible for motility.

Question 16

Which of the following statements about bacterial ribosomes is correct?

Accepted Answer

Bacterial ribosomes are 70S and are the site of protein synthesis.

Question 17

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

Accepted Answer

Protects against desiccation and aids in adherence to surfaces

Question 18

A patient is infected with a bacterium that can survive boiling water and harsh chemicals. Which structure is most likely responsible for this resistance?

Accepted Answer

Endospore

Question 19

Which of the following best describes group translocation in bacteria?

Accepted Answer

A process where a transported substance is chemically modified as it passes through the membrane

Question 20

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

Accepted Answer

Pili are involved in genetic exchange and can transfer antibiotic resistance genes.

Prokaryotic Cell Structure, Function, and Staining in Microbiology

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