Q.Identify the incorrect statement about the Gram positive bacteria.

Gram-positive bacterial cell walls are thick, single-layered, rich in peptidoglycan, and contain teichoic acid; they have no outer membrane and therefore no lipopolysaccharide (LPS), which is instead a hallmark of Gram-negative cell walls.

Check each statement against the true structure of a Gram-positive cell wall:

1. "Teichoic acid absent" — teichoic acids are polymers of glycerol/ribitol phosphate that are woven through the peptidoglycan mesh specifically in Gram-positive walls; their presence (not absence) is one of the standard identifying features of Gram-positive bacteria. So this statement is factually incorrect.
2. "High percentage of peptidoglycan is found in cell wall" — correct; Gram-positive walls can be 40-90% peptidoglycan by weight, far more than Gram-negative walls (5-20%).
3. "Cell wall is single layered" — correct in the usual textbook sense: the Gram-positive wall is a single thick peptidoglycan layer directly outside the plasma membrane, unlike the Gram-negative wall which has a thin peptidoglycan layer PLUS a separate outer membrane (making it effectively multilayered). …

The bacterial cell wall is built of peptidoglycan (murein), not cellulose.

The cell wall of bacteria is composed of peptidoglycan (also called murein) — a mesh-like polymer of two alternating sugar derivatives, N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM), cross-linked by short peptide chains. This rigid layer:

• gives the bacterial cell its shape and mechanical strength,
• protects it from osmotic lysis, …