Questions: Endotoxin Multiple Choice determines bacterial shape. is found in Gram-positive cells. is toxic due to the effects of the peptide side chains. consists of lipopolysaccharide. may have different effects depending on the bacterial species.

The answer is the fourth one (D): consists of lipopolysaccharide.

Explanation for each option:

1. Determines bacterial shape: This is incorrect. The shape of a bacterium is primarily determined by its cell wall structure and cytoskeleton, not by endotoxins.

2. Is found in Gram-positive cells: This is incorrect. Endotoxins are found in the outer membrane of Gram-negative bacteria, not Gram-positive bacteria.

3. Is toxic due to the effects of the peptide side chains: This is incorrect. The toxicity of endotoxins is primarily due to the lipid A component of the lipopolysaccharide, not the peptide side chains.

4. Consists of lipopolysaccharide: This is correct. Endotoxins are a component of the outer membrane of Gram-negative bacteria and consist of lipopolysaccharides (LPS).

5. May have different effects depending on the bacterial species: While this statement can be true, it is not the defining characteristic of endotoxins. The primary defining feature is that they consist of lipopolysaccharides.

Summary: Endotoxins are components of the outer membrane of Gram-negative bacteria and consist of lipopolysaccharides. Therefore, the correct answer is that endotoxins consist of lipopolysaccharide.