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Question #46794
The Question
A researcher induces a mutation in a monocot plant (e.g., wheat) that completely knocks out its Abscisic Acid (ABA) receptor proteins. The plant is subsequently subjected to a severe soil water deficit. Based on the principles of plant anatomy and physiology, which of the following best describes the most likely state of the plant's leaves and its vascular integrity?
Options
- A.
Bulliform cells remain turgid keeping the leaf unrolled, as their flaccidity is strictly dependent on ABA-mediated efflux of potassium ions.
- B.
Bulliform cells become flaccid causing the leaf to roll inwards, but failure of stomatal closure leads to excessive transpirational pull and subsequent xylem cavitation.
- C.
The leaf rolls inwards to minimize surface area, which successfully compensates for the open stomata, maintaining the cohesion-tension of the xylem sap.
- D.
Stomata close through a secondary ethylene-mediated pathway, but the xylem vessels undergo embolism due to the physical collapse of the bulliform cells.
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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
Bulliform Cells|Hormone Half-life Logic|Stomatal Apparatus Anatomy
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Distinguishing between direct physical responses to water loss (bulliform cell flaccidity) and hormone-mediated physiological responses (ABA-induced stomatal closure).
The trap lies in assuming that leaf rolling alone is sufficient to prevent water loss (Option C) or that bulliform cell turgor is strictly regulated by ABA just like guard cells (Option A).
It also tests the application of the Cohesion-Tension theory, linking unregulated transpiration directly to xylem cavitation.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Anatomy of Flowering Plants - Class 11 |
| Concept | Bulliform Cell Function |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |