Which of the following timelines best represents the major milestones in the development of cell theory?

• A. Virchow states all cells come from pre-existing cells → Robert Hooke observes cells → Schleiden and Schwann propose cell theory
• B. Robert Hooke observes cells → Virchow states all cells come from pre-existing cells → Schleiden and Schwann propose cell theory
• C. Schleiden and Schwann propose cell theory → Robert Hooke observes cells → Virchow states all cells come from pre-existing cells
• D. Robert Hooke observes cells → Schleiden and Schwann propose cell theory → Virchow states all cells come from pre-existing cells

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, including their origin and role as the basic unit of life.
2. Step 2: Recall the contributions of Robert Hooke. In 1665, Robert Hooke was the first to observe and describe cells using a microscope. He coined the term 'cell' after observing the structure of cork.
3. Step 3: Recognize the contributions of Schleiden and Schwann. In 1838-1839, Matthias Schleiden and Theodor Schwann proposed the foundational principles of cell theory, stating that all living organisms are composed of cells and that the cell is the basic unit of life.
4. Step 4: Understand the role of Rudolf Virchow. In 1855, Rudolf Virchow added to cell theory by stating that all cells arise from pre-existing cells, a concept known as 'Omnis cellula e cellula.'
5. Step 5: Arrange the milestones in chronological order: (1) Robert Hooke observes cells, (2) Schleiden and Schwann propose cell theory, and (3) Virchow states all cells come from pre-existing cells. This timeline reflects the correct sequence of events in the development of cell theory.