Cell theory was put forward by: (JRF Plant Science 2020)

✅ Explanation: Matthias Schleiden and Theodor Schwann are credited with formulating the cell theory, which states that all living organisms are composed of cells, and cells are the basic unit of life.
📌 Other Options Explanations:● (A) Singh & Nicolson: They proposed the fluid mosaic model of the cell membrane.● (B) Leeuwenhoek: He is known for his improvements to the microscope and observations of microorganisms.● (D) Calvin & Melvin: Melvin Calvin is known for his work on the Calvin cycle in photosynthesis.
🔑Key Points::• The cell theory was proposed by Schleiden and Schwann.• Matthias Schleiden was a German botanist who examined a large number of plants and observed that all plants are composed of different kinds of cells that form the tissues of the plant.• Theodore Schwann was a British Zoologist who studied different types of animal cells and reported that cells had a thin outer layer which is today known as the plasma membrane. He also concluded, based on his studies on plant tissues, that the presence of a cell wall is a unique character of the plant cells.• Schleiden and Schwann together formulated the cell theory.

🔴 Related Information::• Rudolf Virchow gave the concept of Omnis cellula – e – cellula which means new cells arise from the pre-existing cells.• He modified the hypothesis of Schleiden and Schwann to give the cell theory a final shape. Cell theory as understood today is:
-All living organisms are composed of cells and products of cells.
-All cells arise from pre-existing cells.• Robert Brown, a British Biologist discovered the nucleus in the year 1831.• Anton van Leeuwenhoek discovered the first living cell in 1674. Algae Spirogyra was the first living cell observed under a microscope by him.