Match the scientists in Column I with their key discoveries or propositions in Column II.
| Column I (Scientist) | Column II (Discovery/Proposition) |
|---|---|
| a) Schleiden | 1. Proposed that cells arise from pre-existing cells |
| b) Schwann | 2. First saw and described a live cell |
| c) Leeuwenhoek | 3. Observed that all plants are composed of cells |
| d) Robert Brown | 4. Discovered the nucleus |
| e) Rudolf Virchow | 5. Stated that animal cells have a thin outer plasma membrane |