Who gave the cell theory?

Explanation

### Step-by-Step Solution:

1. **Identify the Scientists**: The cell theory was developed by two main scientists: Matthias Schleiden and Theodor Schwann. Schleiden was a German botanist, and Schwann was a British zoologist.

2. **Schleiden's Contribution**: In 1838, Matthias Schleiden proposed that all plants are made up of cells. He studied various plants and their cellular structures, which led him to conclude that cells are the fundamental building blocks of plant life.

3. **Schwann's Contribution**: In 1839, Theodor Schwann extended this idea to animals. He studied animal cells and discovered that they also consist of cells. He identified the presence of a membrane in animal cells, which is now known as the plasma membrane.

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