Function of rectal papillae of cockroach is

Options

A. absorption of amino acids
B. absorption of fats
C. absorption of glucose
D. absorption of water

Answer

### Step-by-Step Solution:

1. **Understanding the Structure**: The rectal papillae are located in the hindgut of the cockroach, which is part of its elementary canal. The elementary canal is divided into three sections: the foregut, midgut, and hindgut.

2. **Identifying the Parts of the Hindgut**: The hindgut is further divided into three parts: the ileum, colon, and rectum. The rectum is the final part of the hindgut and has an opening to the exterior through the anus.

3. **Composition of the Rectum**: The inner layer of the rectum consists of epithelial tissue, which includes aggregations of columnar cells. These aggregations form structures known as rectal papillae.

4. **Function of Rectal Papillae**: The primary function of the rectal papillae is to regulate the absorption of water and ions. They play a crucial role in the reabsorption process, allowing the cockroach to conserve water and maintain homeostasis.

5. **Eliminating Incorrect Options**: In the context of the question, options such as absorption of amino acids, fats, and glucose are incorrect. These nutrients are absorbed earlier in the digestive process, specifically in the foregut and midgut, and do not reach the rectum.

6. **Final Answer**: Therefore, the correct answer to the question regarding the function of rectal papillae in cockroaches is the absorption of water.