Roland Ott, age 11, of Willowdale. Ontario, Canada, for his question:

How does a plant digest its food?

A plant, of course, has no mouth or human type digestive system. Nor does it prefer our type of food. We could not survive on a diet of carbon dioxide gas plus a few chemicals dissolved in water. But this is the basic diet of the plant world. You would think that every plant would need a very complicated system of internal organs to convert this diet into useable food. But this is not so. A vine has no intestines, a tree has no stomach and a rose bush has none of the internal equipment we need to digest our food.

The amazing job is done on a small scale, within countless tiny living cells. The first stage is done by the leafy cells that contain green chlorophyll. This green stuff is the magic ingredient that creates sugar from airy carbon dioxide and water. It requires the energy of sunlight and the process is called photosynthesis    meaning the sunshine recipe. The sugar from photosynthesis is the basic plant food. Its molecules are sifted to other cells to be processed into a vast assortment of substances and used to build new cells, create seeds and perfume for the flowery petals. Sugar is created only during the daylight. These more elaborate operations, of food processing may continue day and night.