Question

Cell theory was formulated by ____________.

• A. Antonie Von Leeuwenhoek
• B. Schleiden and Schwann
• C. Robert Brown
• D. Singer and Nicolson

Hint:

While Schleiden and Schwann formulated the baseline Cell Theory, it had a major limitation: it could not explain *how* new cells are created. This missing link was resolved in 1855 by Rudolf Virchow, who introduced the phrase: \[ \text{\textit{Omnis cellula-e cellula}} \quad \Longrightarrow \quad \text{New cells arise only from pre-existing cells} \] Together, these contributions define the modern cell theory.

Answer 1

The Correct Option is B

Step 1: Know what cell theory is.
Cell theory states the basic principles that all living things are made of cells.
Step 2: Recall the botanist.
Matthias Schleiden, a German botanist, concluded in 1838 that all plants are made of cells.
Step 3: Recall the zoologist.
Theodor Schwann, a German zoologist, found in 1839 that animals too are made of cells and their products.
Step 4: Combine their work.
Together Schleiden and Schwann formulated the classic cell theory, so this pair is the answer.
Step 5: Reject the others, part one.
Leeuwenhoek first saw live cells, and Robert Brown discovered the nucleus, but neither framed the cell theory.
Step 6: Reject the others, part two and conclude.
Singer and Nicolson gave the fluid mosaic model of the membrane, not the cell theory. So the answer is Schleiden and Schwann.
\[ \boxed{\text{Schleiden and Schwann}} \]