Amphibians have :-

Options

A. Incomplete double circulation
B. Complete double circulation
C. Open circulation
D. Single circulation

Answer

**Step-by-Step Text Solution:**

1. **Understanding the Circulatory System**: Amphibians possess a unique circulatory system that is characterized by a three-chambered heart. This heart consists of two atria and one ventricle.

2. **Oxygenated and Deoxygenated Blood**: In amphibians, the right atrium receives deoxygenated blood from the body, while the left atrium receives oxygenated blood from the lungs. Both types of blood mix in the single ventricle.

3. **Incomplete Double Circulation**: Due to the mixing of oxygenated and deoxygenated blood in the ventricle, amphibians exhibit what is known as "incomplete double circulation." This means that while they have two circuits (one for the lungs and one for the body), the blood is not completely separated.

4. **Comparison with Other Circulatory Systems**:
- **Complete Double Circulation**: This is found in organisms with a four-chambered heart, such as birds and mammals, where oxygenated and deoxygenated blood do not mix.
- **Open Circulation**: This type is found in arthropods and mollusks, where blood is not confined to vessels.
- **Single Circulation**: This is typical in fish, where blood passes through the heart only once during each complete circuit of the body.

5. **Conclusion**: Therefore, the correct answer to the question "Amphibians have:" is "incomplete double circulation."

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