What is the main difference in human and frog RBCs?

Options

A. Human RBC are nonnucleated
B. Hemoglobin is found only in human RBC
C. Human RBC have nucleus
D. Human RBC are multinucleate

Answer

To answer the question about the main difference between human and frog red blood cells (RBCs), we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Red Blood Cells (RBCs)**:
- RBCs, or erythrocytes, are crucial components of blood responsible for transporting oxygen and carbon dioxide. They contain hemoglobin, which binds to oxygen.

2. **RBC Characteristics in Humans**:
- In humans (and most mammals), RBCs are **non-nucleated**. This means that they do not have a nucleus when they are mature.
- The loss of the nucleus occurs during the reticulocyte stage of development, allowing for more space to carry hemoglobin and, consequently, more oxygen.

3. **RBC Characteristics in Frogs**:
- In contrast, frog RBCs are **nucleated**. They retain their nucleus even in their mature form.
- Frog RBCs are also larger and have an oval shape, whereas human RBCs are typically biconcave.

4. **Comparison of Oxygen Needs**:
- Humans require more oxygen than frogs due to higher metabolic demands. Therefore, the adaptation of losing the nucleus in human RBCs allows for increased hemoglobin content and oxygen transport efficiency.

5. **Conclusion**:
- The main difference between human and frog RBCs is that **human RBCs are non-nucleated**, while frog RBCs are nucleated.

### Final Answer:
The main difference in human and frog RBCs is that **human RBCs are non-nucleated**, whereas frog RBCs are nucleated.

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