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Question 596
Microbiology → General
Classification
Question
SSBAQuestion Header
Which feature is responsible for the ability of a bacterium to take up Gram stain?
Question Stem
A bacterial isolate is classified as Gram positive. Which structural feature accounts for this classification?
Options
A
Peptidoglycan in the cell wall
B
A spherical cellular shape
C
A rod-shaped cellular form
D
Ability to grow without oxygen
E
Ability to alter function according to oxygen availability
Explanation
Gram-positive bacteria take up Gram stain in association with peptidoglycan in the cell wall. Bacteria not capable of taking up Gram stain are classified as Gram negative. Morphology and oxygen requirement are separate methods of classification.
Option Validity
B) Spherical morphology defines cocci rather than Gram positivity.
C) Rod-shaped morphology defines bacilli rather than Gram positivity.
D) Growth without oxygen concerns anaerobic classification rather than Gram staining.
E) Altering function according to oxygen availability describes facultative anaerobic behaviour.
Further Reading
Saxena R. Textbook for MRCOG-1: Basic Sciences in Obstetrics and Gynaecology. Chapter 6 — Microbiology and Immunology: Bacteria. Printed page 183.