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

The first living organisms on Earth doubtless arose in an aqueous environment, and the course of evolution has been shaped by the proper­ ties of the aqueous medium in which life began.

Virtually every chemical reaction in a cell occurs at a significant rate only because of the presence of enzymes.

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.