Who concluded that all plants are composed of cells?

• A. Rudolf Virchow
• B. Theodor Schwann
• C. Robert Hooke
• D. Matthias Schleiden

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the historical context of cell theory development. Cell theory is a fundamental principle in biology that describes the properties of cells as the basic unit of life.
2. Step 2: Learn about Matthias Schleiden's contribution to cell theory. Schleiden was a German botanist who concluded that all plants are composed of cells, which was a significant step in the development of cell theory.
3. Step 3: Differentiate between the contributions of other scientists mentioned in the problem. For example, Theodor Schwann extended Schleiden's work to animals, Rudolf Virchow proposed that cells arise from pre-existing cells, and Robert Hooke was the first to observe cells under a microscope.
4. Step 4: Recognize that Schleiden's work focused specifically on plant cells, making him the correct answer to the question.
5. Step 5: Use this information to reinforce your understanding of the collaborative nature of scientific discoveries, as cell theory was developed through the contributions of multiple scientists.