Linda Beam, age 12, of Lancaster, Penn 

What exactly is Photosynthesis?

The word, as all Andy’s readers know, means putting together with light  and it can be translated as the sunshine recipe, for it is the marvelous chemical process by which green plants make simple sugar from air, water and sunlight  This plant sugar is then used to build the woody stems and fragile foliage, fragrant flowers and piercing roots, lush fruit, crisp nuts, all the promising seeds and everything else in the plant world 

Photosynthesis has been one of Nature’s most closely guarded secrets  Until recently, science could not duplicate the sunshine recipe carried on by every green leaf during the daylight hours  As the mystery was solved, we had to revise some of our old ideas about the marvelous recipe  One of these ideas concerns the very oxygen we breathe and where it cones from 

Science has long known the ingredients which a plant urea in photosynthesis  It uses carbon dioxide and water  The carbon dioxide is present in small traces in the air, It is put there by all breathing animals and plants, for it is the waste gas we breathe out  The water used in photosynthesis comes from the soil, toted up from the roots to plant cells which contain green chlorophyll  This substance is a clear liquid teeming with tiny green bodies called chloroplasts 

In a square inch of leaf surface, there may be 300 million of these midget chloroplasts  Water reaches the cells carrying chlorophyll through small vessels called vascular bundles  Air, with its mixture of gases including traces of carbon dioxide, seeps in and out of the plant through tiny pores called stomata; The energy of sunlight triggers the chlorophyll into action  Molecules of carbon dioxide and water are broken apart and their atoms reassembled to make molecules of simple glucose sugar • the basic plant food  The molecule of glucose contains six atoms of carbon, 12 atoms of hydrogen and six atoms of oxygen  Each particle of water has two atoms  of hydrogen and one of oxygen  Each particle of carbon dioxide has two atoms of oxygen and one of carbon  The recipe calls for 12 particles of water and sax of carbon dioxide, The particles are broken into separate atoms and rearranged  Some are used to make the molecule of glucose 

The remaining atoms are waste products which seep out through the stomata  Some of the oxygen and hydrogen atoms link together to form water vapor  The rest is free oxygen which takes to the air and is wafted by the breezes around the world  This is the oxygen which the plant world supplies for its own respiration and for the breathing processes of all living things 

In the past, it was thought that our oxygen supply name from the breakdown of the carbon dioxide molecules during photosynthesis  Then radioactive materials were used to trace the process more carefully  The surplus oxygen was then found to come from the breakdown of water particles ‑ and the secret of the sunshine recipe was at long, long last revealed.