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Question #46898
The Question
A researcher isolates a functional enzyme complex in vitro that continuously converts a substrate into a product. To simulate stress-induced metabolic downregulation, Abscisic Acid (ABA) is added to the medium, but the reaction rate remains completely unaffected. Based on NCERT principles of the 'living state' and plant growth regulators, which of the following is the most accurate deduction regarding this system?
Options
- A.
The system lacks intact membrane receptors and secondary messenger cascades (e.g., Ca2+) required for ABA signal transduction, proving it is a living reaction but not a living state.
- B.
ABA is a steroid hormone that requires intracellular receptors to alter gene expression, which are inherently absent in cell-free in vitro systems.
- C.
The in vitro reaction is considered a living thing, but ABA fails to act because its antagonistic hormone, Gibberellic Acid (GA), is absent.
- D.
ABA directly binds to the active sites of metabolic enzymes to cause competitive inhibition, but the in vitro enzymes have denatured allosteric sites.
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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
Metabolism vs. In-vitro Reactions|Secondary Messenger Cascade|Abscisic Acid (ABA) Antagonism
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Distinguishing between a 'living reaction' (pure biochemical conversion) and a 'living state' (homeostatic regulation via signal transduction).
The trap lies in assuming hormones directly inhibit enzymes (Option D) or misidentifying ABA's chemical nature (Option B).
It tests the deep synthesis of Chapter 1 (The Living World) and Chapter 15 (Plant Growth and Development).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | The Living World - Class 11 |
| Concept | Metabolism vs. In-vitro Reactions |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |