RBCs have biconcave, disc-like structure and they are tiny and flexible. Give reason.

Explanation

**Step-by-Step Solution:**

1. **Definition of RBCs**: Red Blood Cells (RBCs) are the cells in our blood responsible for transporting oxygen from the lungs to the rest of the body and returning carbon dioxide from the body back to the lungs.

2. **Shape of RBCs**: RBCs have a biconcave, disc-like structure. This means they are shaped like a doughnut without a hole, which provides them with a unique form.

3. **Reason for Biconcave Shape**: The biconcave shape increases the surface area of the RBCs. A larger surface area allows for more efficient absorption and transport of oxygen. This is crucial because the primary function of RBCs is to carry oxygen to tissues and organs.

...