Question 1

Which component is unique to the cell envelope of Gram-negative bacteria and is responsible for its endotoxin activity?

Accepted Answer

Lipopolysaccharide (LPS)

Question 2

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

Accepted Answer

Archaea

Question 3

Which of the following best explains why lysozyme is ineffective against methanogenic Archaea?

Accepted Answer

They lack peptidoglycan and have β-1,3 bonds in pseudomurein.

Question 4

Which structure is primarily responsible for the selective permeability of microbial cells?

Accepted Answer

Cytoplasmic (cell) membrane

Question 5

A patient is infected with a bacterium that resists phagocytosis and forms biofilms. Which structure most likely contributes to these properties?

Accepted Answer

Capsule

Question 6

Which of the following is a function of the periplasmic space in Gram-negative bacteria?

Accepted Answer

Storage of enzymes and proteins

Question 7

Which arrangement of flagella would you expect to find in Pseudomonas species?

Accepted Answer

Polar

Question 8

A bacterium is observed to move toward a nutrient source. What is the term for this behavior, and what is the underlying mechanism in E. coli?

Accepted Answer

Chemotaxis; run and tumble

Question 9

Which of the following statements about endospores is TRUE?

Accepted Answer

They are survival structures found only in Gram-positive genera such as Bacillus and Clostridium.

Question 10

Which of the following best describes the chemical structure of bacterial peptidoglycan?

Accepted Answer

Alternating N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) linked by β-1,4 glycosidic bonds

Question 11

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

Accepted Answer

Thick peptidoglycan layer with teichoic acids

Question 12

Which of the following structures is responsible for DNA transfer during bacterial conjugation?

Accepted Answer

Sex pili

Question 13

A microbe is found to contain gas vesicles. What is the primary function of these structures?

Accepted Answer

Buoyancy regulation

Question 14

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

Accepted Answer

Prevention of osmotic lysis

Question 15

Which of the following statements about the endosymbiotic theory is supported by evidence?

Accepted Answer

Mitochondria and chloroplasts have circular DNA and bacterial-like ribosomes.

Question 16

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

Accepted Answer

Archaea lack peptidoglycan in their cell walls.

Question 17

Which of the following is a correct match between organism and its Gram reaction, shape, and arrangement?

Accepted Answer

Bacillus: Gram-positive, rod, chains

Question 18

Which of the following is a function of teichoic acids in Gram-positive bacteria?

Accepted Answer

Contributing to cell wall rigidity and ion regulation

Question 19

Which of the following is TRUE regarding the difference between fimbriae and pili?

Accepted Answer

Fimbriae are for attachment, while pili are involved in DNA transfer.

Question 20

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

Accepted Answer

Gram-positive, cocci, chains

Microbial Cell Structure and Function: Study Guide

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