Biochemistry asks how the remarkable properties of living organisms arise from the thousands of different biomolecules. - Albert L. Lehninger

Perhaps the most remarkable property of living cells and organisms is their ability to reproduce themselves for countless generations with nearly perfect fidelity. This continuity of inherited traits implies constancy, over millions of years, in the structure of the molecules that contain the genetic information.

The remarkable similarity of metabolic pathways and gene sequences across the phyla argues strongly that all modern organisms are derived from a common evolutionary progenitor by a series of small changes (mutations), each of which conferred a selective advantage to some organism in some ecological niche.

The upper limit of cell size is probably set by the rate of diffusion of solute molecules in aqueous systems.