Yeast cells produce ethanol (alcohol) and carbon dioxide (CO2) as byproducts of fermentation in anaerobic respiration.

Here's a breakdown:

* Anaerobic Respiration: This occurs when there is a lack of oxygen.

* Fermentation: This is a metabolic process that allows yeast to generate energy (ATP) in the absence of oxygen.

* Byproducts: Ethanol and carbon dioxide are the main byproducts of this process.

This is why you see bubbles in bread dough (CO2) and why beer and wine have an alcoholic content (ethanol).