Powdery mildews, truffles, and most molds belong to this group of fungi. Yeasts, like other fungi, have no chlorophyll. They obtain their energy through a process called fermentation. During fermentation, sugars and starches are changed into alcohol and carbon dioxide gas. Athe the same time, energy is released.
Bakers add yeast to bread dough.
As the dough bakes, the yeast produces carbon dioxide. This causes the bread to rise. The carbon dioxide also produces hundreds of tiny bubbles in the bread, which you can see as holes in a slice of bread. Yeasts are unicellular, but they can clump together to form chains of cells. Yeasts reproduce by forming spores or by budding.