question_answer 45)

  Briefly give the contributions of the following scientists in formulating the cell theory (a) Rudolf Virchow (b) Schleiden and Schwann

Answer:

                   (a) Rudolf Virchow <1855) first explained that the cells divide and new cells are formedfrom the pre-existing cells (omniscellula e cellula). Virchow was the first to demonstrate that the cell theory applies to diseased tissue as wellas to healthy tissue. He also engaged his research in the fields of archeology andanthropology.             (b) Schleiden and Schwann observed the cells and cell membranes for the first time. Theyproposed the cell theory which explains that the animal and plant cells are composedof cells and product of cells. Theodore Schwann (1839) studied different types of animal cells and reported that cells hada thin outer layer which is called as plasma membrane. Schleiden also concluded on plant studies, i.e., the presence of cell wall is a unique character of plant cells. Thus, theyproposed that plants and animals are composed of cells and their products.