Joe Synowlecki, age 16, of Marquette, Mich.:

WHERE DO WE FIND GLYCOSIDES?

Glycosides are a class of complex chemical compounds that occur in plants. They are broken down by the action of plant enzymes into sugars, among which glucose is generally included, and into other substances.

The term "glucoside" is often used synonymously with glycoside, but in its more specific meaning it refers to glycosides that yield glucose.

Each glycoside in a plant is hydrolyzed (converted in a reaction with water) by an enzyme, usually a specific enzyme found in the same plant. The enzyme emulsion, however, causes hydrolysis of several glycosides.

The enzymes and glycosides are stored in separate plant cells until the reaction products of the glycosides are needed and the enzymes are activated.

Since the glycosides are bitter tasting, it is believed they help keep birds and insects from eating seeds and fruit before they achieve full growth, by which time the glycosides have been converted to sweet sugars.