Cockroach mainly excretes___________.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question:** The question asks what substance is primarily excreted by cockroaches. We need to identify the main nitrogenous waste product they excrete.

2. **Identifying Excretion in Cockroaches:** Cockroaches are known to excrete nitrogenous waste. The primary form of nitrogenous waste in many terrestrial organisms, including cockroaches, is uric acid.

3. **Uric Acid as a Waste Product:** Uric acid is a moderately toxic nitrogenous waste that is less soluble in water. This characteristic is important because it allows cockroaches to conserve water, which is crucial for their survival in terrestrial environments.

4. **Uricotelic Organism:** Cockroaches are classified as uricotelic organisms, meaning they primarily excrete uric acid. This adaptation helps them minimize water loss.

5. **Formation of Uric Acid:** Uric acid is synthesized in the body from ammonia, which is a more toxic nitrogenous waste. The conversion of ammonia to uric acid allows cockroaches to safely excrete nitrogen without losing excessive amounts of water.

6. **Conclusion:** Therefore, the blank in the question can be filled with "uric acid."

**Final Answer:** Cockroach mainly excretes **uric acid**.

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