Questions: What type of blood cell is biconcave and lacks a nucleus when they are mature? Multiple Choice Platelets Red blood cells White blood cells Macrophages

The answer is the second one (or B): Red blood cells.

Explanation for each option:

• Platelets: These are small cell fragments involved in blood clotting and do not have a biconcave shape.
• Red blood cells: These cells are indeed biconcave and lack a nucleus when they are mature. This shape increases their surface area for gas exchange and allows them to deform as they pass through narrow capillaries.
• White blood cells: These cells are part of the immune system and have a nucleus. They are not biconcave.
• Macrophages: These are a type of white blood cell that engulfs and digests cellular debris and pathogens. They have a nucleus and are not biconcave.

Summary: Red blood cells are the type of blood cell that is biconcave and lacks a nucleus when they are mature.