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Question #46808
The Question
A plant is subjected to a targeted mutation that significantly reduces the accuracy of aminoacyl-tRNA synthetase. Despite normal rates of photosynthesis and abundant sucrose accumulation in the source leaves, the plant's roots exhibit severe starvation. Cellular analysis reveals an inability to maintain a proton gradient across the companion cell membrane. Which of the following statements correctly identifies the primary physiological bottleneck?
Options
- A.
Defective translation of carrier proteins prevents the secondary active transport of sucrose into the companion cells.
- B.
Impaired transcription of the sucrose transporter gene prevents the facilitated diffusion of sucrose into the sieve tube elements.
- C.
Misfolded aquaporins in the sieve tube elements prevent the endosmosis of water from the xylem, halting mass flow.
- D.
Inaccurate charging of tRNA directly inhibits the active unloading of sucrose at the sink, causing a bottleneck at the roots.
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
Companion Cell-Sieve Tube Symport|Protein Denaturation Specificity|Nucleic Acid Structural Stability
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Integrating Molecular Biology (Translation fidelity) with Plant Physiology (Phloem loading).
Students often memorize 'phloem loading is active' but fail to recognize that the active transport mechanism relies on membrane proteins whose functional integrity depends entirely on accurate tRNA charging during translation.
The trap in Option B tests the distinction between transcription and translation, as well as active transport versus facilitated diffusion.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Anatomy of Flowering Plants - Class 11 |
| Concept | Companion Cell-Sieve Tube Symport |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |