Final answer:
Cell theory is a fundamental principle in biology, representing the idea that the cell is the basic unit of life. It evolved through observations and studies by countless scientists, notably Robert Hooke who first described cells, and was later developed into a comprehensive theory by Schleiden, Schwann, and Virchow.
Step-by-step explanation:
Cells are the fundamental units of life, essentially forming the building blocks for all organisms. Cell theory developed through a series of scientific discoveries over several centuries. In 1665, Robert Hooke first coined the term "cells" when observing dead cork tissue under a microscope, likening the chambers he saw to the rooms or 'cells' that monks lived in. However, it was not until Antonie van Leeuwenhoek later observed living cells, did we begin to truly understand their significance.
The development of cell theory progressed significantly when Matthias Jakob Schleiden and Theodor Schwann proposed in 1839 that all living things are made of cells, and this became a key aspect of the theory. Later, Rudolf Virchow's observations that cells arise from other cells solidified the concept, leading to the cell theory we accept today. This theory posits that all organisms are composed of one or more cells, the cell is the basic unit of life, and all cells arise from pre-existing cells.