Which of the following is not correct? (a) Robert Brown discovered the cell. (b) Schleiden and Schwann formulated the cell theory. (c) Virchow explained that cells are formed from pre-existing cells. (d) A unicellular organism carries out its life activities within a single cell.

Statement (a) Robert Brown discovered the cell is not correct

• The term cell was first coined by Robert Hooke in 1665 when he described “cellulae” in cork under a microscope

• Robert Brown’s landmark contribution in 1831 was the recognition and naming of the cell nucleus, not the discovery of the cell itself

Statement (b) Schleiden and Schwann formulated the cell theory is correct

• In 1838 Matthias Schleiden concluded that all plant tissues are composed of cells

• In 1839 Theodor Schwann extended this principle to animals, together founding the unified cell theory

Statement (c) Virchow explained that cells are formed from pre-existing cells is correct

• In 1855 Rudolf Virchow asserted omnis cellula ex cellula, establishing that new cells arise only by division of existing cells

Statement (d) A unicellular organism carries out its life activities within a single cell is correct

• Unicellular organisms such as bacteria and protozoa perform all metabolic, reproductive, and homeostatic functions within one cell