When yeast is mixed with carbohydrates and liquid, which process primarily occurs?

• A. Protein synthesis, forming new enzymes from amino acids
• B. Nitrogen fixation, converting atmospheric nitrogen to ammonia
• C. Photosynthesis, generating glucose and oxygen
• D. Fermentation, producing ethanol and carbon dioxide

Answer: (D)

Verified step by step guidance

1. Identify the key components involved in the process: yeast, carbohydrates, and liquid. Yeast is a type of fungus that can metabolize sugars under certain conditions.
2. Recall that yeast primarily performs fermentation when oxygen is limited or absent. Fermentation is an anaerobic process where carbohydrates (like glucose) are broken down to produce energy.
3. Understand that during fermentation, yeast converts carbohydrates into ethanol (alcohol) and carbon dioxide as byproducts. This process allows yeast to generate ATP without using oxygen.
4. Eliminate other options by matching their definitions: protein synthesis involves making proteins from amino acids, nitrogen fixation converts atmospheric nitrogen to ammonia (done by certain bacteria), and photosynthesis produces glucose and oxygen (done by plants and some microbes).
5. Conclude that the primary process occurring when yeast is mixed with carbohydrates and liquid is fermentation, which produces ethanol and carbon dioxide.