California Cosmetology Written ExamSafety and Infection ControlEasy
A cosmetology instructor is teaching students to identify bacteria by shape under a microscope. Round bacteria that appear singly, in pairs, or in clusters and chains are classified as which shape?
- AVibrio
- BSpirilla
- CCocci
- DBacilli
Show answer & explanationAnswer & explanation
Correct answer: C. Cocci
Cocci are round-shaped bacteria that can appear singly or grouped as diplococci, staphylococci, or streptococci. Bacilli are rod-shaped and spirilla are spiral/curved, so they do not match the description.
Why the other options are wrong
- A. Vibrio is a comma-shaped subtype of spiral bacteria, not round.
- B. Spirilla are spiral or corkscrew-shaped.
- D. Bacilli are rod-shaped, not round.
Bacteria Shapes
Bacteria are classified into three basic shapes: round (cocci), rod-shaped (bacilli), and spiral (spirilla).
- Cocci: round, can cluster (staph) or chain (strep)
- Bacilli: rod-shaped, cause tetanus/tuberculosis
- Spirilla: spiral/wavy, cause syphilis/Lyme-type diseases
Memory trick: Cocci = Circles, Bacilli = Bars, Spirilla = Springs