Give one difference between the RBCs of frog and those of rat.

Explanation

**Step-by-Step Solution:**

1. **Identify the Organisms**: The question asks for a difference between the red blood cells (RBCs) of two different organisms: frogs and rats. Frogs belong to the class Amphibia, while rats belong to the class Mammalia.

2. **Examine the Structure of RBCs**:
- **Frog RBCs**: The red blood cells in frogs are biconvex in shape, meaning they have a bulging appearance on both sides.
- **Rat RBCs**: In contrast, the red blood cells in rats are concave, which means they have a dimpled or indented shape.

...