Frequency of bowel movements varies widely among individuals, as well as varying widely for any single individual. In studies on the subject, approximately 50 to 70 percent of people surveyed report having a single daily bowel movement. Outliers range from one movement every three days to three movements a day.
Cell theory was eventually formulated in 1839. This is usually credited to Matthias Schleiden and Theodor Schwann. However, many other scientists like Rudolf Virchow contributed to the theory. The three tenets to the cell theory are as described below: All living organisms are composed of one or more cells.
1. Schleiden (a botanist) and Schwann (a zoologist): believed that all plants and animals consist of cells. 2. Virchow: cells come from preexisting cells. C. The Cell Theory: three generalizations: 1. All organisms are composed of one or more cells. 2. The cell is the smallest unit having the properties of life. 3. The continuity of life arises directly from the growth and division of single cells. I. Basic Aspects of Cell Structure and Function. A. Structural Organization of Cells. 1. The cell is the smallest entity that still retains the characteristics of life. 2. All cells have three basic parts: a.