Question 1

Which of the following statements best describes a key difference between the domains Bacteria and Archaea?

Accepted Answer

Bacteria possess peptidoglycan in their cell walls, whereas Archaea do not.

Question 2

A bacterium is observed to have a thick peptidoglycan layer, teichoic acids, and no outer membrane. What color would it appear after Gram staining, and why?

Accepted Answer

Purple, because the thick peptidoglycan layer retains the crystal violet stain.

Question 3

Which structure is primarily responsible for the corkscrew motility observed in spirochetes?

Accepted Answer

Periplasmic flagella (axial filaments)

Question 4

During binary fission, which event occurs immediately after the chromosome is replicated?

Accepted Answer

The chromosome is drawn to opposite ends of the cell.

Question 5

Which of the following best explains why Gram-negative bacteria are generally more resistant to antibiotics like penicillin?

Accepted Answer

Their outer membrane contains lipopolysaccharide, which acts as a barrier to many drugs.

Question 6

A scientist isolates a bacterium that grows slowly and is resistant to many drugs. Staining reveals red/pink cells after an acid-fast stain. What is the most likely explanation for these observations?

Accepted Answer

The bacterium has a waxy cell wall rich in mycolic acids.

Question 7

Which of the following best describes the function of fimbriae in bacteria?

Accepted Answer

Attachment to surfaces and formation of biofilms.

Question 8

A bacterial cell is exposed to a hypotonic environment. Which feature of its cell wall helps prevent lysis?

Accepted Answer

Peptidoglycan layer

Question 9

Which equation best represents the relationship between surface area and volume for a spherical bacterial cell, and why is this relationship important?

Accepted Answer

$$SA = 4\pi r^2$, V$$ = \frac{4}{3}\pi $$r^3$$; a higher surface area-to-volume ratio allows efficient nutrient uptake.

Question 10

Which of the following is NOT a function of the bacterial glycocalyx?

Accepted Answer

Facilitation of gene transfer between cells

Question 11

Which of the following best explains why Mycoplasma bacteria are unique among prokaryotes?

Accepted Answer

They lack a cell wall entirely.

Question 12

Which structure allows bacteria to transfer genetic material during conjugation?

Accepted Answer

Pili

Question 13

A Gram-negative bacterium is exposed to anionic detergents. What is the expected outcome and why?

Accepted Answer

The bacterium will be less susceptible because its outer membrane acts as a barrier.

Question 14

Which of the following is a correct sequence of events in binary fission?

Accepted Answer

Chromosome replication → cell elongation → septum formation → cell separation

Question 15

Which feature is present in Gram-negative bacteria but absent in Gram-positive bacteria?

Accepted Answer

Outer membrane containing lipopolysaccharide

Question 16

A bacterium is observed to move toward a chemical attractant. Which process is responsible for this behavior?

Accepted Answer

Chemotaxis

Question 17

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

Accepted Answer

They form protein channels in the outer membrane, allowing passage of small molecules.

Question 18

Which of the following arrangements describes a chain of rod-shaped bacterial cells?

Accepted Answer

Streptobacilli

Question 19

Which of the following is a consequence of a low surface area-to-volume ratio in large bacterial cells?

Accepted Answer

Limited nutrient uptake and slower growth

Question 20

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

Accepted Answer

Maintaining cell shape and aiding in cell division

Introduction to Prokaryotes: Structure, Classification, and Key Features

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