Question

yeast cells under anaerobic conditions
multiple choice
switch to oxidative respiration.
produce oxygen.
die.
push the glycolytic pathway backward.
produce ethyl alcohol (ethanol).

Explanation:

Yeast cells are facultative anaerobes. In anaerobic conditions, they undergo alcoholic fermentation. Glycolysis occurs first, converting glucose to pyruvate. Then, instead of entering the Krebs cycle (which requires oxygen), pyruvate is converted to ethyl alcohol (ethanol) and carbon dioxide. This is a way for yeast to regenerate NAD+ so that glycolysis can continue.

• "Switch to oxidative respiration" is incorrect because oxidative respiration requires oxygen.
• "Produce oxygen" is incorrect as yeast in anaerobic conditions do not produce oxygen.
• "Die" is incorrect as yeast can survive and carry out fermentation anaerobically.
• "Push the glycolytic pathway backward" is not what happens; glycolysis proceeds forward, and then the end - product of glycolysis (pyruvate) is further metabolized.

Answer:

Produce ethyl alcohol (ethanol).