Which one of the following statements is in- correct?

Options

A. In cockroaches and prawns excretion of waste material occurs through malpighian tubules
B. In ctenophores, locomotion is mediated by comb plates.
C. In Fasciala flame cells take part in excretion
D. Earthworms are hermaphrodites and yet cross fertilization take place among them.

Answer

To solve the question "Which one of the following statements is incorrect?", we will analyze each statement provided in the video transcript step by step.

### Step 1: Analyze the first statement
**Statement:** In cockroaches and prawns, excretion of waste material occurs through malpighian tubules.

- **Explanation:**
- In cockroaches, the excretory system does indeed utilize malpighian tubules for the excretion of waste.
- However, in prawns, the excretory function is performed by the green glands, not malpighian tubules.
- Therefore, this statement is incorrect.

### Step 2: Analyze the second statement
**Statement:** In stenophores, locomotion is mediated by comb plates.

- **Explanation:**
- This statement is correct. Stenophores, also known as ctenophores, use comb plates (or ctenes) for locomotion.

### Step 3: Analyze the third statement
**Statement:** In flatworms, flame cells take part in excretion.

- **Explanation:**
- This statement is also correct. Flame cells are specialized excretory cells found in flatworms that help in the removal of waste.

### Step 4: Analyze the fourth statement
**Statement:** Earthworms are hermaphrodites and yet cross-fertilization takes place among them.

- **Explanation:**
- This statement is correct as well. Earthworms possess both male and female reproductive organs (hermaphroditic) and typically engage in cross-fertilization.

### Conclusion
After analyzing all the statements, we find that the first statement regarding cockroaches and prawns is incorrect. Hence, the answer to the question is:

**Answer:** The incorrect statement is the first one.

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