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Question #45219
The Question
Malonate is a classic competitive inhibitor of a specific enzyme in the Tricarboxylic Acid (TCA) cycle. If malonate is introduced into an actively respiring mitochondrial suspension, which of the following statements regarding the subsequent biochemical consequences is INCORRECT?
Options
- A.
The apparent Km of the target enzyme increases, but the inhibition can be overcome by adding a high concentration of succinate.
- B.
The target enzyme is unique among TCA cycle enzymes because it is anchored to the inner mitochondrial membrane rather than being dissolved in the matrix.
- C.
The sole substrate-level phosphorylation step of the TCA cycle, which yields GTP, occurs immediately after the step blocked by malonate.
- D.
The inhibition prevents the reduction of FAD to FADH2, thereby directly obstructing electron flow through Complex II of the electron transport chain.
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
Succinate_Dehydrogenase|Malonate|Krebs_Cycle
Why This Question Is Tricky
Common Mistakes
Process Sequence & Functional Overlap Trap: The conceptual pivot relies on students memorizing the exact sequential order of the Krebs cycle rather than just its components.
Students often know that SLP and FADH2 production occur close to each other, but fail to recall that SLP (Succinyl-CoA to Succinate) generates the very substrate (Succinate) that is subsequently targeted by the malonate-inhibited enzyme (Succinate Dehydrogenase).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Biomolecules - Class 11 |
| Concept | Enzyme Activation Energy Lowering |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |