Birds excrete nitrogenous waste as

Options

A. Uric acid
B. Urea
C. `NH_(3)`
D. Guanine

Answer

**Step-by-Step Solution:**

1. **Understanding Nitrogenous Wastes**:
- Nitrogenous wastes are products of protein metabolism that need to be excreted from the body. The main types of nitrogenous wastes are ammonia, urea, and uric acid.

2. **Types of Nitrogenous Wastes**:
- **Ammonia (NH3)**: Highly toxic and requires a lot of water to be safely excreted. It is primarily found in aquatic animals that can afford to lose large amounts of water.
- **Urea**: Less toxic than ammonia and requires a moderate amount of water for excretion. It is commonly excreted by amphibians (like frogs) and mammals (like humans).
- **Uric Acid**: The least toxic form of nitrogenous waste, which requires minimal water for excretion. This is particularly advantageous for organisms that need to conserve water.

3. **Adaptation in Birds**:
- Birds excrete nitrogenous waste in the form of uric acid. This adaptation is crucial for their survival, especially since they are often in flight and cannot afford to lose significant amounts of water.

4. **Form of Excretion**:
- Uric acid is excreted as a paste or pellet, which minimizes water loss. This is a significant adaptation for birds, allowing them to maintain hydration while flying.

5. **Conclusion**:
- Therefore, the correct answer to the question is that birds excrete nitrogenous waste as uric acid.

**Final Answer**: Birds excrete nitrogenous waste as uric acid.

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