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Question #47489
The Question
A biochemical engineer compares citric acid production in two setups: Setup X is an in vitro cell-free system containing only Acetyl CoA, Oxaloacetic acid (OAA), and extracted citrate synthase. Setup Y is an in vivo bioreactor containing an aerobic culture of Aspergillus niger. All of the following statements correctly describe the metabolic principles governing these setups EXCEPT:
Options
- A.
Setup X represents a 'living reaction' but not a 'living thing', whereas Setup Y represents an integrated living system subject to cellular regulation.
- B.
In Setup Y, the accumulation of ATP and citrate will trigger allosteric feedback inhibition of earlier glycolytic enzymes, a regulatory mechanism absent in Setup X.
- C.
Setup X will proceed until chemical equilibrium is reached, whereas Setup Y maintains a continuous metabolic flux as long as substrates are supplied.
- D.
Without a mitochondrial electron transport chain to oxidize NADH, the isolated in vitro Setup X must shift to enzymatic fermentation to synthesize citric acid.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Evolutionary_Exception
Tackle problems where standard rules evolve or change based on specific environmental constraints.
Concepts Behind This Question
Deuteromycetes|Basidiomycetes|Karyogamy_Delay
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often conflate industrial 'fermentation technology' with the strict biochemical definition of anaerobic fermentation.
They also fail to isolate the specific enzymatic requirements of citrate synthase (which does not involve NADH) from the rest of the TCA cycle, leading them to falsely believe an isolated in vitro setup would require fermentation to proceed.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Biological Classification - Class 11 |
| Concept | Deuteromycetes 'Fungi Imperfecti' |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |