Which statement is true about cell theory?

• A. All organisms are made of cells
• B. Cells do not come from preexisting cells
• C. The cell membrane is the only part of the cell
• D. DNA is not found in cells

Answer: (A)

Life is organized around cells. The statement that all organisms are made of cells captures the fundamental idea that every living thing, whether a single cell or many, is built from cells and that those cells perform the basic processes of life. That view is the essence of cell theory, which recognizes cells as the basic units of life.

The idea that cells do not come from preexisting cells conflicts with what we observe about reproduction and growth; new cells arise when existing cells divide to form daughter cells. The notion that the cell membrane is the only part of the cell ignores the many organelles and structures inside that work together, like the nucleus, mitochondria, ribosomes, and cytoplasm. And saying DNA is not found in cells is incorrect because DNA is the genetic material housed within cells, in the nucleus of eukaryotes and in organelles like mitochondria (and in the cytoplasm of prokaryotes, in a region called the nucleoid).

So the true statement is that all organisms are made of cells.