Which one of the following animals has two separate circulatory pathways?

Options

A. Shark
B. Frog
C. Lizard
D. Whale

Answer

To determine which animal has two separate circulatory pathways, we need to analyze the circulatory systems of the given options:

1. **Shark**:
- The shark is a cartilaginous fish (Pisces) and has a two-chambered heart, consisting of one atrium and one ventricle.
- This type of heart leads to mixing of oxygenated and deoxygenated blood, meaning it does not have two separate circulatory pathways.
- **Conclusion**: Incorrect option.

2. **Frog**:
- Frogs are amphibians and have a three-chambered heart, which includes two atria and one ventricle.
- This arrangement also results in some mixing of oxygenated and deoxygenated blood, so it does not possess two separate circulatory pathways.
- **Conclusion**: Incorrect option.

3. **Lizard**:
- Lizards are reptiles and also have a three-chambered heart.
- Similar to frogs, this heart structure allows for some mixing of blood, which means it does not have two distinct circulatory pathways.
- **Conclusion**: Incorrect option.

4. **Whale**:
- Whales are mammals and possess a four-chambered heart, which includes two atria and two ventricles.
- This structure prevents the mixing of oxygenated and deoxygenated blood, allowing for two separate circulatory pathways: the pulmonary pathway (where deoxygenated blood is sent to the lungs) and the systemic pathway (where oxygenated blood is distributed to the body).
- **Conclusion**: Correct option.

**Final Answer**: The animal that has two separate circulatory pathways is the **whale**.

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