Cell wall was first observed by

Options

A. Robert Brown
B. Robert Hooke
C. Schleiden
D. Robert Hill

Answer

To answer the question, "Cell wall was first observed by," we will analyze the options provided and determine the correct answer step by step.

### Step-by-Step Solution:

1. **Identify the Options**: The options given are Robert Brown, Robert Hook, Skledon, and Robert Hill.

2. **Evaluate Robert Brown**:
- Robert Brown is known for discovering the nucleus in cells.
- Since he did not discover the cell wall, this option is incorrect.

3. **Evaluate Skledon**:
- Skledon, along with Schwann, contributed to the development of the cell theory, which emphasizes the importance of cells in living organisms.
- However, he did not specifically discover the cell wall, making this option incorrect as well.

4. **Evaluate Robert Hill**:
- Robert Hill is known for Hill's reaction, which is related to photosynthesis and involves the transfer of electrons from water to Hill's reagent.
- This does not pertain to the discovery of the cell wall, so this option is also incorrect.

5. **Evaluate Robert Hook**:
- Robert Hook is credited with the discovery of cork cells in 1665.
- He used a microscope to examine thin slices of cork and observed tiny hollow compartments, which he named "cells."
- These compartments correspond to what we now understand as cell walls, particularly in plant cells. Therefore, Robert Hook is indeed the first to observe the cell wall.

6. **Conclusion**:
- Based on the evaluations, the correct answer is Robert Hook, as he was the first to observe the cell walls in cork cells.

### Final Answer:
The cell wall was first observed by **Robert Hook**.