Of the following statements, which one is correct regarding the biconcave shape of the red blood cell (RBC)?

• A. The biconcave shape allows RBCs to carry more mitochondria for energy production.
• B. The biconcave shape is due to the presence of a rigid cell wall.
• C. The biconcave shape increases the surface area-to-volume ratio, enhancing gas exchange.
• D. The biconcave shape prevents RBCs from passing through narrow capillaries.

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the structure of a red blood cell (RBC). RBCs are specialized cells in the blood responsible for transporting oxygen and carbon dioxide. They lack organelles such as mitochondria and a nucleus, and their unique biconcave shape is a key feature.
2. Step 2: Analyze the biconcave shape of RBCs. This shape is not due to a rigid cell wall, as RBCs do not have a cell wall. Instead, they have a flexible plasma membrane that allows them to deform and pass through narrow capillaries.
3. Step 3: Consider the functional advantage of the biconcave shape. The biconcave shape increases the surface area-to-volume ratio, which is crucial for efficient gas exchange. This allows oxygen and carbon dioxide to diffuse more effectively across the cell membrane.
4. Step 4: Evaluate the incorrect statements. RBCs do not carry mitochondria because they rely on anaerobic metabolism for energy. Additionally, the biconcave shape does not prevent RBCs from passing through narrow capillaries; it actually facilitates their movement through these small spaces.
5. Step 5: Conclude that the correct statement is: 'The biconcave shape increases the surface area-to-volume ratio, enhancing gas exchange.' This is the primary reason for the unique shape of RBCs and its importance in their function.