Nutrition Science and Everyday Application - beta v 0.1

136 ALICE CALLAHAN, PHD, HEATHER LEONARD, MED, RDN, AND TAMBERLY POWELL, MS, RDN
or stem. (Salt is a notable exception.) Ultimately, photosynthesis connects to every meal and
every food a person consumes.
Main Structures and Summary of Photosynthesis
Photosynthesis generally takes place in the leaves of plants. It is a multi-step process that
requires sunlight, carbon dioxide (CO 2 , found in the air), and water (H 2 O, from the soil). After
the process is complete, the plant releases oxygen into the air (O 2 , essential for many living
organisms) and produces the simple carbohydrate molecule of glucose, which can be used
as an energy source by the plant, converted to starch and stored for a later energy source,
or converted into other organic molecules such as fats, proteins and vitamins. This glucose
contains the energy that all living organisms need to survive.
Figure 3.5. Depiction of photosynthesis in plants. The carbohydrates produced are stored in or
used by the plant.
The basic formula for photosynthesis is as follows:
6CO 2 + 6H 2 O + sun’s energy = C 6 H 12 O 6 + 6O 2
Another way of saying this:
Photosynthesis uses:
Photosynthesis produces:
6 molecules of carbon dioxide (6CO 2 )
6 molecules of water (6H 2 O)
the sun’s energy
1 molecule of glucose (C 6 H 12 O 6 )
6 molecules of oxygen (6O 2 )