Question 1

Which of the following statements best explains why the cytoplasmic membrane is considered a good permeability barrier in bacterial cells?

Accepted Answer

The hydrophobic fatty acid tails in the phospholipid bilayer prevent the free passage of polar and charged molecules.

Question 2

Which feature distinguishes archaeal cytoplasmic membranes from those of bacteria and eukaryotes?

Accepted Answer

Archaeal membranes contain isoprenoid chains and ether linkages in their phospholipids.

Question 3

A bacterium is found to have a thick peptidoglycan layer, teichoic acids, and no outer membrane. Which type of cell envelope does it most likely possess?

Accepted Answer

Gram-positive

Question 4

Which of the following best describes the function of the proton motive force in bacterial cells?

Accepted Answer

It drives the active transport of solutes and powers flagellar rotation.

Question 5

Which transport system in bacteria involves the chemical modification of the transported substance and is driven by phosphoenolpyruvate?

Accepted Answer

Group translocation (phosphotransferase system)

Question 6

Why are ABC transporters particularly advantageous for bacteria living in nutrient-poor environments?

Accepted Answer

Their substrate-binding proteins have high affinity for solutes, allowing efficient uptake at low concentrations.

Question 7

Which of the following statements about peptidoglycan is correct?

Accepted Answer

It consists of alternating N-acetylglucosamine and N-acetylmuramic acid residues joined by $$\beta-1$$,4 linkages.

Question 8

A researcher treats a bacterial culture with penicillin. Which of the following best explains why Gram-positive bacteria are more susceptible to penicillin than Gram-negative bacteria?

Accepted Answer

Gram-positive bacteria have a thick peptidoglycan layer that is the primary target of penicillin, while Gram-negative bacteria have an outer membrane that limits access.

Question 9

Which component of the Gram-negative bacterial cell envelope is responsible for its toxicity in humans?

Accepted Answer

Lipid A portion of lipopolysaccharide (LPS)

Question 10

Which of the following is NOT a function of S-layers in prokaryotes?

Accepted Answer

Serving as the main site of ATP synthesis

Question 11

A bacterium is found to survive extreme desiccation and heat. Microscopy reveals a refractile structure inside the cell. Which adaptation is most likely responsible for this resistance?

Accepted Answer

Formation of endospores containing dipicolinic acid and small acid-soluble spore proteins (SASPs)

Question 12

Which of the following best describes the role of magnetosomes in certain bacteria?

Accepted Answer

They allow the cell to orient and migrate along magnetic field lines (magnetotaxis).

Question 13

Which of the following cell surface structures is primarily involved in the formation of biofilms and attachment to surfaces?

Accepted Answer

Capsules and slime layers

Question 14

Which statement best explains why lysozyme is ineffective against most archaeal cell walls?

Accepted Answer

Archaeal cell walls lack peptidoglycan and, if present, contain pseudomurein with $$\beta-1$$,3 linkages.

Question 15

Which of the following is a key difference between bacterial flagella and archaeal archaella?

Accepted Answer

Bacterial flagella are composed of flagellin and powered by the proton motive force, while archaella are composed of unrelated proteins and powered by ATP hydrolysis.

Question 16

A bacterium exhibits 'run and tumble' behavior in response to a chemical gradient. What is the primary advantage of this behavior?

Accepted Answer

It enables the bacterium to bias its movement toward attractants or away from repellents, enhancing survival.

Question 17

Which of the following is a function of eukaryotic mitochondria?

Accepted Answer

Respiration and oxidative phosphorylation to produce ATP

Question 18

Which evidence supports the endosymbiotic origin of mitochondria and chloroplasts?

Accepted Answer

They contain circular DNA genomes and ribosomes similar to those of Bacteria.

Question 19

Which cytoskeletal element is primarily responsible for the movement of chromosomes during eukaryotic cell division?

Accepted Answer

Microtubules

Question 20

Which of the following statements about eukaryotic flagella is correct?

Accepted Answer

They are composed of a bundle of nine pairs of microtubules surrounding a central pair and move by a whiplike motion powered by ATP.

Microbial Cell Structure and Function: Study Notes for Microbiology Students

Study Guide - Practice Questions

Study Guide - Flashcards