Chemical Reactions with Water

A diagram of a green plant taking in (inward arrows) water (H Subscript 2 O) and carbon dioxide (CO Subscript 2), and giving out (outward arrows) oxygen (O Subscript 2) and glucose (C Subscript 6 H Subscript 12 O Subscript 6) is shown.

Water provides hydrogen (H) and oxygen (O) atoms for making many biological molecules. This plant is conducting photosynthesis, using the O from water to make atmospheric oxygen ( $O_{2}$ ), and combining the H from water with carbon dioxide ( $C O_{2}$ ) to make sugar
( $C_{6} H_{12} O_{6}$ ). Many other reactions transfer OH from water to biological molecules. This happens when we digest proteins and starch.