Which of the following statements are correct about the modes of excretion ?

Options

A. All bony fishes are ammonotelic.
B. Aquatic mammals are ureotelic
C. Insects such as cockroach are ammonotelic.
D. Tadpole of frog is ureotelic

Answer

To solve the question regarding the modes of excretion, we need to analyze each statement provided in the options carefully.

### Step-by-Step Solution:

1. **Understanding Modes of Excretion**:
- Excretion is the process by which waste products are eliminated from the body. Different organisms have different modes of excretion based on their habitat and physiology.

2. **Analyzing Each Statement**:
- **Statement 1**: "All bony fishes are ammonotelic."
- This statement is **incorrect**. While many bony fishes excrete ammonia (ammonotelic), freshwater bony fishes primarily excrete ammonia, but not all bony fishes do. Some, like certain marine bony fishes, may excrete urea.

- **Statement 2**: "Aquatic mammals are ureotelic."
- This statement is **correct**. Aquatic mammals, such as whales and dolphins, excrete urea as their primary nitrogenous waste, making them ureotelic.

- **Statement 3**: "Insects such as Cockroach are ammonotelic."
- This statement is **incorrect**. Cockroaches and most insects are uricotelic, meaning they excrete uric acid, which conserves water.

- **Statement 4**: "Tadpole of frog is ureotelic."
- This statement is **incorrect**. Tadpoles primarily excrete ammonia, making them ammonotelic. As they mature into adult frogs, their mode of excretion changes to ureotelic.

3. **Conclusion**:
- The only correct statement among the options provided is the second one: "Aquatic mammals are ureotelic."

### Final Answer:
- The correct statement about the modes of excretion is: **Aquatic mammals are ureotelic.**