The Question is from neet-botany respiration-in-plants fermentation, and it was created by the author B VENKAT

Question

During alcoholic fermentation by yeast, a crucial intermediate is formed before the production of ethanol. This intermediate, which is also associated with muscle fatigue in animals, is:

B VENKAT · Accepted Answer

## CORE INFORMATION
✓ **Answer**: C
## CONCEPT FRAMEWORK
 **Primary Concept**: Alcoholic Fermentation
 **Related Topics**: Cellular Respiration, Anaerobic Metabolism, Lactic Acid Fermentation
 **Prerequisites**: Understanding of glycolysis and fermentation pathways.
## SOLUTION PATHWAY
**Given Information**:
  The question asks for the intermediate formed during alcoholic fermentation before ethanol production, and also associated with muscle fatigue.
  
**Method & Steps**:
 1. Understand Alcoholic Fermentation:
  Reasoning: Alcoholic fermentation is an anaerobic process (occurs without oxygen) used by yeast and some bacteria to produce energy from glucose.  It involves glycolysis followed by the reduction of pyruvate to ethanol.
  Formula/Rule:  Glucose $ightarrow$ 2 Pyruvate + 2 ATP + 2 NADH  (Glycolysis)
                       2 Pyruvate $ightarrow$ 2 Acetaldehyde + 2 $CO_2$
                       2 Acetaldehyde + 2 NADH $ightarrow$ 2 Ethanol + 2 NAD$^+$ 
 2. Identify the Intermediate:
  Working: The intermediate between pyruvate and ethanol is acetaldehyde. Pyruvate is decarboxylated (loses a carbon dioxide molecule) to form acetaldehyde. Acetaldehyde is then reduced by NADH to form ethanol, regenerating NAD$^+$ which is crucial for glycolysis to continue.
  Key Point:  The reduction of acetaldehyde to ethanol regenerates NAD+, which is essential for the continuation of glycolysis. Without this regeneration, glycolysis would halt.
 3. Muscle Fatigue Connection:
  Result: In animals, under anaerobic conditions (e.g., during intense exercise), pyruvate is converted to lactate (lactic acid) instead of ethanol. The buildup of lactate in muscles leads to muscle fatigue.
  Verification: Acetaldehyde is not directly involved in muscle fatigue, but its production in yeast fermentation parallels the production of lactate in animal muscle cells under anaerobic conditions. Both are formed from pyruvate as alternative pathways in the absence of oxygen.
 ## OPTION ANALYSIS
[A] :x: Pyruvate: Pyruvate is the starting point, not an intermediate between pyruvate and ethanol.
[B] :x: Lactate: Lactate is produced during lactic acid fermentation in animals, not alcoholic fermentation in yeast.
[C] ✓: Acetaldehyde: Acetaldehyde is the direct intermediate between pyruvate and ethanol in alcoholic fermentation.
[D] :x: Citrate: Citrate is part of the citric acid cycle (Krebs cycle), an aerobic process, not involved in fermentation.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Confusing alcoholic fermentation with lactic acid fermentation:  Remember the end products differ (ethanol vs. lactate).
  2. Forgetting the role of NADH and NAD+: NADH is the reducing agent, and its regeneration is crucial for the continuation of glycolysis.
 **Quick Tips**:
  1.Remember the key steps: glycolysis, pyruvate decarboxylation, acetaldehyde reduction.
  2.Associate lactate with muscle fatigue in animals and ethanol with alcoholic fermentation in yeast.

B VENKAT · Answer

Pyruvate

B VENKAT · Answer

Lactate

B VENKAT · Answer

The correct Option is "Acetaldehyde"

B VENKAT · Answer

Citrate

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