_______________ discovered cells while looking at a piece of cork under the micro-scope.

Explanation

**Step-by-Step Solution:**

1. **Identify the Context**: The question asks about the scientist who discovered cells while examining cork under a microscope.

2. **Recall Historical Facts**: Remember that the discovery of cells is a significant event in biology, linked to the development of microscopy.

3. **Name the Scientist**: The scientist who is credited with this discovery is Robert Hooke.

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