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Question #47668
The Question
In Saccharomyces cerevisiae, the incomplete oxidation of pyruvic acid under anaerobic conditions is a critical survival mechanism that eventually becomes a lethal bottleneck. Which of the following statements regarding this metabolic pathway is INCORRECT?
Options
- A.
The primary metabolic necessity of this pathway is the continuous regeneration of NAD+ to sustain the oxidation of glyceraldehyde-3-phosphate in glycolysis.
- B.
The decarboxylation of pyruvic acid to acetaldehyde is directly coupled with the oxidation of NADH + H+ to NAD+.
- C.
The organism poisons itself to death when ethanol concentration reaches about 13%, primarily due to plasma membrane fluidization and protein denaturation.
- D.
Less than seven percent of the energy in glucose is released during this entire process, and not all of it is trapped as high-energy bonds of ATP.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Regulatory_Failure
Understand how NOT, EXCEPT, and logical constraints are used to manipulate exam results.
Concepts Behind This Question
Glycolysis Redox Balance|Pyruvate Decarboxylation Complexity|Fermentation Limitations
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often view 'alcoholic fermentation' as a single concerted reaction rather than a two-step enzymatic sequence.
The trap relies on conflating the decarboxylation step (carbon loss via pyruvic acid decarboxylase) with the reduction step (redox homeostasis/NAD+ regeneration via alcohol dehydrogenase).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Respiration in Plants - Class 11 |
| Concept | Pyruvate Decarboxylation Complexity |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |