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Question #47551
The Question
In an experiment, a specific metabolic inhibitor is applied to the source leaves of an angiosperm, selectively disabling the H+/Sucrose symporters on the plasma membrane of companion cells. According to Munch's Mass Flow Hypothesis, which of the following sequences of events best describes the immediate systemic fallout of this disruption?
Options
- A.
Phloem loading ceases → Solute potential in sieve tubes becomes less negative → Water influx from xylem stops → Turgor pressure gradient collapses.
- B.
Phloem loading ceases → Solute potential in sieve tubes becomes more negative → Water efflux to xylem increases → Mass flow halts.
- C.
Active transport of water into sieve tubes halts → Hydrostatic pressure drops → Sucrose diffuses back into mesophyll cells → Sink starvation.
- D.
Companion cells undergo necrosis → Plasmodesmatal connections close → Sieve tube elements lose their enucleated state → Transport efficiency drops.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Comparative_Analysis
Sharpen your ability to evaluate multiple scenarios and distinguish between competing potential answers.
Concepts Behind This Question
Tracheids|Vessels|Radial vs Conjoint Bundles|Plant Kingdom
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize that 'water moves into the phloem to create pressure' but fail to connect the active transport of sucrose to the exact thermodynamic changes (solute potential becoming more negative) that drive this osmotic influx.
The trap lies in understanding the inverse relationship between solute concentration and solute potential (Ψs), where adding solute makes the value more negative.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Plant Kingdom - Class 11 |
| Concept | Vascular Evolution Sequence |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |