The most toxic introgenous waste excreted by many bony fishes, aquatic amphibians and aquatic insect is

Options

A. Ammonia
B. Urea
C. Uric acid
D. Both 2 & 3

Answer

To solve the question about the most toxic nitrogenous waste excreted by many bony fishes, aquatic amphibians, and aquatic insects, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Types of Nitrogenous Wastes**:
- Nitrogenous wastes are products of protein metabolism and can be classified into three main types: ammonia, urea, and uric acid.

2. **Understand the Toxicity Levels**:
- Ammonia is known to be the most toxic form of nitrogenous waste.
- Urea is less toxic than ammonia but more toxic than uric acid.
- Uric acid is the least toxic among the three.

3. **Consider the Organisms in Question**:
- The question specifies bony fishes, aquatic amphibians, and aquatic insects.
- These organisms typically excrete ammonia because they live in water, which allows them to dilute the ammonia and eliminate it efficiently.

4. **Define Ammonotelic Organisms**:
- Organisms that excrete ammonia as their primary nitrogenous waste are referred to as ammonotelic organisms.
- Bony fishes are prime examples of ammonotelic organisms.

5. **Conclude the Answer**:
- Given that ammonia is the most toxic nitrogenous waste and is excreted by the specified organisms, the answer to the question is **ammonia**.

### Final Answer:
The most toxic nitrogenous waste excreted by many bony fishes, aquatic amphibians, and aquatic insects is **ammonia**.

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