Question 1

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

Accepted Answer

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

Question 2

A patient is diagnosed with pneumonia caused by Streptococcus pneumoniae. The strain is found to be highly virulent. Which structural feature is most likely responsible for this increased virulence?

Accepted Answer

Production of a thick capsule (glycocalyx) surrounding the cell wall

Question 3

Which of the following correctly matches the bacterial structure with its primary function?

Accepted Answer

Ribosomes – Protein synthesis

Question 4

A laboratory technician is using a Shaeffer-Fulton stain and observes highly refractile structures within Bacillus cells. What are these structures, and what is their main function?

Accepted Answer

Endospores; they allow survival in harsh environmental conditions

Question 5

Which of the following statements about peptidoglycan is TRUE?

Accepted Answer

It is composed of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) linked by $$\beta\ 1-4$$ glycosidic bonds.

Question 6

A researcher is studying a bacterium that lacks a cell wall. Which genus is most likely being studied, and what is a key implication for antibiotic treatment?

Accepted Answer

Mycoplasma; it is resistant to antibiotics that target peptidoglycan synthesis

Question 7

Which of the following best describes the function of porins in Gram-negative bacteria?

Accepted Answer

They serve as channels for the transport of small molecules across the outer membrane.

Question 8

A strain of Neisseria gonorrhoeae is able to adhere strongly to human epithelial cells. Which structure is primarily responsible for this adherence?

Accepted Answer

Common pili (fimbriae)

Question 9

Which of the following is a correct statement about the Gram-positive bacterial cell wall?

Accepted Answer

It contains a thick layer of peptidoglycan and teichoic acids.

Question 10

Which of the following best explains why Bacillus anthracis spores are difficult to eliminate from contaminated environments?

Accepted Answer

They contain a DPA-calcium complex that confers resistance to heat, chemicals, and radiation.

Question 11

A scientist is studying a bacterium with a star-like shape. To which group does this bacterium most likely belong?

Accepted Answer

Stellate bacteria

Question 12

Which of the following is a function of the bacterial capsule (glycocalyx)?

Accepted Answer

Protection against phagocytosis

Question 13

Which of the following best describes the genetic material found in the nucleoid of a typical bacterial cell?

Accepted Answer

A single, circular, double-stranded DNA molecule not surrounded by a nuclear envelope

Question 14

A bacterium is found to have a single, long, hollow projection used for conjugation. Which structure is this, and what is its genetic basis?

Accepted Answer

F pilus; coded for by plasmid genes

Question 15

Which of the following statements about bacterial ribosomes is correct?

Accepted Answer

They consist of 50S and 30S subunits and are the site of protein synthesis.

Question 16

A patient is infected with a Gram-negative bacterium. Upon cell lysis, the patient develops fever and shock. Which component is most likely responsible for these symptoms?

Accepted Answer

Lipopolysaccharide (LPS) layer (endotoxin)

Question 17

Which of the following best describes the action of lysozyme on bacterial cell walls?

Accepted Answer

It breaks $$\beta\ 1-4$$ glycosidic bonds between N-acetylglucosamine and N-acetylmuramic acid.

Question 18

Which of the following inclusions would you expect to find in a bacterium living in hot sulfur springs, and what is its function?

Accepted Answer

Sulfur granules; storage of sulfur for energy metabolism

Question 19

A bacterium is observed to have multiple flagella located at both poles of the cell. What is the correct term for this flagellar arrangement?

Accepted Answer

Amphitrichous

Question 20

Which of the following best explains why penicillins and cephalosporins are most effective against actively growing Gram-positive bacteria?

Accepted Answer

They inhibit the formation of peptidal bridges during cell wall synthesis, which is most active during binary fission.

Bacterial Cell Structure: An Overview

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