Question

Yeast produces ethanol by

• A. partial breakdown of sugars aerobically
• B. partial breakdown of sugars anaerobically
• C. complete breakdown of sugars aerobically
• D. complete breakdown of sugars anaerobically

Answer 1

The correct option is B partial breakdown of sugars anaerobically

Brewer's yeast is a unicellular fungus that is widely used for fermenting malted cereals and fruit juices, to produce ethanol. Brewer's yeast is known as Saccharomyces cerevisiae.

Yeasts are facultative anaerobes. They usually respire aerobically in the presence of oxygen but can also respire anaerobically in the absence of oxygen.

During the production of ethanol, the yeast respires anaerobically, producing ethyl alcohol (ethanol) and carbon dioxide from the partial breakdown of sugars present in the raw material used for fermentation. This is called alcoholic fermentation or ethanol fermentation.