Which of the following prevents the rupture of bacterial cells by internal osmotic pressure?

• A. Capsule
• B. Plasma membrane
• C. Flagella
• D. Peptidoglycan layer

Answer: (D)

Verified step by step guidance

1. Understand the concept of osmotic pressure in bacterial cells: Osmotic pressure is the force exerted by the movement of water across a semipermeable membrane due to differences in solute concentration inside and outside the cell.
2. Identify the structural components of a bacterial cell relevant to maintaining cell integrity: These include the capsule, plasma membrane, flagella, and the peptidoglycan layer.
3. Analyze the function of each component: The capsule mainly protects against desiccation and immune responses; the plasma membrane controls substance passage but is flexible; flagella are for motility and do not provide structural support.
4. Focus on the peptidoglycan layer: This is a rigid, mesh-like structure surrounding the plasma membrane that provides mechanical strength and prevents the cell from bursting due to internal osmotic pressure.
5. Conclude that the peptidoglycan layer acts as a protective barrier against osmotic lysis by maintaining the cell's shape and resisting internal pressure.