Which of the following statements is a key principle of cell theory?

The statement that all cells arise from preexisting cells is a fundamental principle of cell theory. This principle emphasizes that new cells are produced only through the division of existing cells, which underlines the continuity of life. It reflects the understanding that cell division is a crucial process for growth, repair, and reproduction in living organisms.

This concept is significant as it helps to establish a connection between all forms of life, illustrating that all cellular organisms derive from earlier cellular forms. This principle also supports various biological processes such as development, healing, and propagation of genetic material through cell division.

In contrast, the other statements do not align with the key tenets of cell theory. For instance, while some cells may perform similar functions, the assertion that all cells are identical in function is inaccurate as different types of cells have specialized roles. The idea that cells can only exist independently overlooks the fact that many cells function as part of tissues and organs within multicellular organisms. Lastly, the claim that organisms are made entirely of non-living components contradicts the essence of living organisms, which are composed of living cells and cellular structures.