CMLA Microbiology Basics 2

Question 1

Which staining technique differentiates bacteria based on cell wall peptidoglycan thickness?

Accepted Answer

Gram stain

Answer

The Gram stain exploits differences in peptidoglycan layer thickness: thick walls in Gram-positive bacteria retain crystal violet, while Gram-negative bacteria decolorize and take up safranin.

Question 2

A culture plate shows hemolysis where red blood cells are completely lysed, leaving a clear zone around colonies. This is classified as:

Accepted Answer

Beta hemolysis

Answer

Beta hemolysis indicates complete lysis of red blood cells, producing a clear, transparent zone around the colony on blood agar.

Question 3

Which organism is responsible for causing tuberculosis?

Accepted Answer

Mycobacterium tuberculosis

Answer

Mycobacterium tuberculosis is the causative agent of tuberculosis and is identified by its acid-fast staining property due to mycolic acids in its cell wall.

Question 4

What is the purpose of a Mueller-Hinton agar plate in microbiology?

Accepted Answer

Performing antimicrobial susceptibility testing

Answer

Mueller-Hinton agar is the standard medium used for disk diffusion (Kirby-Bauer) antimicrobial susceptibility testing per CLSI guidelines.

Question 5

Which component of a bacterial cell is the primary target of penicillin?

Accepted Answer

Cell wall peptidoglycan synthesis

Answer

Penicillin inhibits transpeptidase enzymes involved in cross-linking peptidoglycan strands during cell wall synthesis, causing cell lysis.

(CMLA) Certified Medical Laboratory Assistant Practice Test

(CMLA) Certified Medical Laboratory Assistant Practice Test

CMLA Microbiology Basics 2