The venous system of frog differs from that of rat in having

Options

A. Hepatic vein
B. Three vena cavae
C. Renal portal system
D. Hepatic portal system

Answer

**Step-by-Step Solution:**

1. **Identify the Organisms**: The question compares the venous systems of two different organisms: the frog (an amphibian) and the rat (a mammal).

2. **Understand the Venous System**: The venous system is responsible for returning deoxygenated blood back to the heart. In different organisms, this system can have variations based on their physiology and evolutionary adaptations.

3. **Key Features of Frog's Venous System**:
- Frogs possess a **renal portal system**. This system is unique to amphibians and is responsible for transporting blood from the internal organs (especially the hind limbs and kidneys) back to the kidneys.
- The renal portal system allows for the filtration of blood that comes from the digestive and urinary tracts before it returns to the heart.

4. **Key Features of Rat's Venous System**:
- Rats, being mammals, do not have a renal portal system. Instead, they have a more developed venous system that includes a hepatic portal system, which directs blood from the digestive organs to the liver before it returns to the heart.
- The waste elimination in rats occurs through separate structures: the anus and urethra.

5. **Conclusion**: The main difference in the venous system between frogs and rats is the presence of the renal portal system in frogs, which is absent in rats.

6. **Final Answer**: The venous system of frogs differs from that of rats in having a **renal portal system**.

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