where do the casparian bands occur

Options

A. Endodermis
B. Pericycle
C. Periderm
D. Cortex

Answer

To answer the question "Where do the Casparian bands occur?", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Structure of Plant Tissues**:
- Plant tissues are categorized into different types, including epidermis, cortex, endodermis, pericycle, and periderm. Each has distinct characteristics and functions.

2. **Identifying the Role of the Endodermis**:
- The endodermis is a layer of cells that forms the innermost part of the cortex in roots. It acts as a selective barrier regulating the movement of water and nutrients into the vascular system.

3. **Recognizing the Casparian Bands**:
- Casparian bands are specialized structures found in the endodermis. They consist of suberin, a waxy substance that creates a waterproof barrier.

4. **Locating the Casparian Bands**:
- The Casparian bands are located on the radial and tangential walls of the endodermal cells. This thickening prevents passive flow of substances and forces them to pass through the cell membranes, allowing for selective absorption.

5. **Conclusion**:
- Based on the information, we conclude that Casparian bands occur in the endodermis.

### Final Answer:
- The Casparian bands occur in **Option A: Endodermis**.

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