Which layer has more cellulose ?

Options

A. Primary wall
B. Secondary wall
C. Cell membrance
D. Middle lamella

Answer

To determine which layer has more cellulose, we need to analyze the composition of the different layers of plant cells: the primary wall, secondary wall, cell membrane, and middle lamella.

### Step-by-Step Solution:

1. **Identify the Layers**: The layers we need to consider are the primary wall, secondary wall, cell membrane, and middle lamella.

2. **Analyze the Primary Wall**:
- The primary cell wall is primarily composed of cellulose, hemicellulose, and pectin.
- The cellulose content in the primary wall is approximately 20% to 30%.

3. **Analyze the Secondary Wall**:
- The secondary cell wall is made up of cellulose and a substance called lignin, along with hemicellulose.
- The cellulose content in the secondary wall is higher than that of the primary wall, ranging from 35% to 50%.

4. **Consider the Cell Membrane**:
- The cell membrane is not composed of cellulose; it is primarily made of phospholipids and proteins, thus it contains no cellulose.

5. **Consider the Middle Lamella**:
- The middle lamella is primarily made of pectin and does not contain cellulose.

6. **Compare the Cellulose Content**:
- Based on the analysis, the secondary wall has a higher cellulose content (35% to 50%) compared to the primary wall (20% to 30%) and the other layers which do not contain cellulose.

7. **Conclusion**:
- Therefore, the layer that has more cellulose is the **secondary wall**.

### Final Answer:
The layer that has more cellulose is the **secondary wall**.

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