Question

Ethanol fermentation is typically carried out under

• A. Aerobic conditions
• B. Microaerophilic conditions
• C. Phototrophic conditions
• D. Anaerobic conditions

Hint:

Remember: \[ \boxed{\text{Yeast}+\text{Glucose} \longrightarrow \text{Ethanol}+CO_2} \] Ethanol fermentation always takes place under anaerobic conditions.

Answer 1

The Correct Option is D

Concept: Ethanol fermentation is a metabolic process in which microorganisms convert sugars such as glucose into ethanol and carbon dioxide in the absence of oxygen. This process is widely used in brewing, wine production, biofuel manufacturing, and baking industries. The most common organism used is the yeast Saccharomyces cerevisiae.

Step 1: Understand ethanol fermentation.
In ethanol fermentation, glucose is first broken down into pyruvate through glycolysis. In the absence of oxygen, pyruvate is converted into ethanol and carbon dioxide. \[ \boxed{C_6H_{12}O_6 \longrightarrow 2C_2H_5OH+2CO_2+\text{Energy}} \]

Step 2: Importance of anaerobic conditions.
Oxygen is absent during ethanol fermentation. Under anaerobic conditions:
• NADH is oxidized back to NAD$^+$.
• Glycolysis continues to produce ATP.
• Ethanol and carbon dioxide are formed as end products. If oxygen is present, yeast generally performs aerobic respiration instead of fermentation.

Step 3: Eliminate incorrect options.

• Aerobic conditions favor respiration.
• Microaerophilic conditions contain limited oxygen but are not typical for ethanol fermentation.
• Phototrophic conditions involve photosynthetic organisms.
• Ethanol fermentation occurs under anaerobic conditions. Final Answer: \[ \boxed{Option (D) is correct \]