AP-Micro Microbiology: Cell Structure and Function 2

Question 1

Which structural feature allows gram-negative bacteria to be inherently resistant to many antibiotics like penicillin?

Accepted Answer

Outer membrane containing LPS

Answer

The outer membrane of gram-negative bacteria acts as a permeability barrier that excludes many antibiotics, including penicillin, from reaching the peptidoglycan layer.

Question 2

Bacterial flagella rotate to produce movement. Which component anchors the flagellum to the cell membrane and generates torque?

Accepted Answer

Basal body

Answer

The basal body is embedded in the cell membrane and wall, functioning as a motor that uses proton motive force to rotate the flagellum.

Question 3

A microbiologist observes a bacterium with fimbriae. What is the PRIMARY function of these structures?

Accepted Answer

Attachment to host cell surfaces

Answer

Fimbriae (also called pili) are short, hair-like appendages that mediate adhesion of bacteria to host tissues and surfaces.

Question 4

What is the function of porins found in the outer membrane of gram-negative bacteria?

Accepted Answer

Form channels that allow passive diffusion of small molecules

Answer

Porins are transmembrane proteins that form water-filled channels permitting passive diffusion of small hydrophilic molecules across the outer membrane.

Question 5

Which of the following correctly describes the nucleoid region of a prokaryotic cell?

Accepted Answer

A region containing circular DNA not enclosed by a membrane

Answer

The nucleoid is an irregularly shaped region in prokaryotes where the circular chromosomal DNA is compacted, but it lacks a surrounding membrane.

AP Practice Test

AP Practice Test

AP-Micro Microbiology: Cell Structure and Function 2