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.
Which of the following statements regarding the fundamental nature of cells and cell theory are NOT correct? S1: Antonie Von Leeuwenhoek first saw and described a live cell, demonstrating that unicellular organisms are capable of independent existence. S2: Robert Brown is credited with the discovery of the nucleus within a cell in 1831. S3: Theodore Schwann's studies on plant tissues led him to conclude that the presence of cell wall is a unique character of animal cells. S4: The cell theory, initially proposed by Schleiden and Schwann, did not address the mechanism of how new cells are formed. S5: Rudolf Virchow's contribution, "Omnis cellula-e cellula," implies that all living organisms are composed of cells and products of cells.
Correct answer: B — S3 and S5 only
The core concept tested is the foundational principles of cell biology, including the definition of a cell and the historical development of the cell theory, as provided in NCERT. S1: Antonie Von Leeuwenhoek first saw and described a live cell. Unicellular organisms are indeed capable of independent existence and performing essential life functions. This statement is correct. (NCERT Page 88). S2: Robert Brown discovered the nucleus in 1831. This statement is correct. (NCERT Page 88 and Page 100). S3: Theodore Schwann, based on his studies on plant tissues, concluded that the presence of cell wall is a unique character of *plant* cells, not animal cells. Therefore, this statement is NOT correct. (NCERT Page 88). S4: The cell theory formulated by Schleiden and Schwann did not explain how new cells were formed. This was later elucidated by Rudolf Virchow. This statement is correct. (NCERT Page 88). S5: Rudolf Virchow's phrase "Omnis cellula-e cellula" means "all cells arise from pre-existing cells". The idea that "all living organisms are composed of cells and products of cells" was part of the original hypothesis proposed by Schwann and then formulated by Schleiden and Schwann. Therefore, this statement is NOT correct. (NCERT Page 88). Statements S3 and S5 are NOT correct. Final Answer: The final answer is B because statements S3 and S5 are incorrect.
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