HORTICULTURE

Detailed explanation-1: -Scientists once thought that life spontaneously arose from nonliving things. Thanks to experimentation and the invention of the microscope, it is now known that life comes from preexisting life and that cells come from preexisting cells.

Detailed explanation-2: -The unified cell theory states that: all living things are composed of one or more cells; the cell is the basic unit of life; and new cells arise from existing cells. Rudolf Virchow later made important contributions to this theory.

Detailed explanation-3: -Later, in 1858, the German doctor Rudolf Virchow observed that cells divide to produce more cells. He proposed that all cells arise only from other cells.

Detailed explanation-4: -New cells are created from existing cells through a process referred to as the cell cycle. One cell can make a copy of itself and form two new daughter cells. There are two major tasks that have to happen every cell cycle. First, cells have to make an exact copy of their DNA.