Saccharomyces Cerevisiae (yeast)is a single cell eukaryotic organism that is a fungi. It digests food to obtain energy for growth and gets it mostly from sugars like sucrose, fructose and glucose and maltose.
When sugar is present, yeast conducts fermentation to produce alcohol and carbon dioxide by creating a chemical energy.In yeast, high sugar concentrations and high specific growth rates trigger alcoholic fermentation, even under fully aerobic conditions. It is commonly used to leaven bread, mold blue cheese to make it ripe, ferment alcohol, and is used in the molds that produce antibiotics for veterinary and medical use. In bread baking the sugars from the flour or from the added sugar are fermented by the yeast, because the dough is elastic the carbon dioxide gas will not be able escape causing the dough to expand.
Substrates used in the experiment.
The hypothesis before the experiment begun was that glucose would produce more carbon dioxide than the other substrates as it would be easier to break down. Glucose is monosaccharide that is used through glycolysis where it is oxidized and yields energy form of ATP.
Figure1 - The chemical structure of glucose
Fructose is a monosaccharide like glucose, it also contains 3 to 7 carbon atoms and is a simple sugar.
Figure2 - The chemical structure of Fructose
Sorbitol is polyhydric alcohol that can occur naturally or be produced synthetically from glucose
Figure3 - The chemical structure of sorbitol.