Question

Which of the following statements is correct?

• A. Gram negative bacteria are colored purple after Gram staining
• B. Gram negative bacteria are commonly more resistant to antibiotics than Gram positive bacteria
• C. Gram negative bacteria cell wall consists of a thick layer of peptidoglycan outside the plasma membrane
• D. Cell wall of Gram negative bacteria does not contain an outer membrane

Hint:

Think: Gram-negative = thin wall + outer membrane → higher antibiotic resistance.

Answer 1

The Correct Option is B

Step 1: Reviewing Gram-negative bacteria properties.
Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane rich in lipopolysaccharides. This outer membrane forms a barrier, making them more resistant to antibiotics compared to Gram-positive bacteria.
Step 2: Analyzing the options.
(A) Incorrect — Gram-negative bacteria turn pink, not purple, after staining.
(B) Correct — Their outer membrane increases antibiotic resistance.
(C) Incorrect — They have a thin, not thick, peptidoglycan layer.
(D) Incorrect — They DO contain an outer membrane, which is a key feature.
Step 3: Conclusion.
Option (B) correctly describes Gram-negative bacteria.