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Question #45124
The Question
A transgenic tobacco plant is engineered to produce nematode-specific double-stranded RNA (dsRNA) to confer resistance against Meloidogyne incognita. However, a mutant strain of the nematode successfully infects the plant. Molecular analysis of the mutant nematode reveals an abnormal accumulation of long dsRNA in its cytoplasm and a complete failure to activate the RNA-induced silencing complex (RISC). Which of the following best explains the molecular defect in this mutant nematode?
Options
- A.
A defective Dicer enzyme prevents the endonucleolytic cleavage of long dsRNA into short interfering RNAs (siRNAs).
- B.
A mutation in the Argonaute protein prevents the unwinding of dsRNA and the subsequent degradation of the target mRNA.
- C.
The nematode's RNA polymerase fails to simultaneously transcribe the sense and antisense strands from the ingested plant genome.
- D.
The target mRNA in the nematode undergoes rapid alternative splicing, thereby escaping recognition by the RISC complex.
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
RNAi|Dicer|RISC|mRNA|Nematode (Meloidogyne incognita)
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Understanding the sequential enzymatic steps of RNAi (Dicer -> siRNA -> RISC -> mRNA degradation) and the spatial separation of events (dsRNA synthesis in the plant vs.
RNAi execution in the nematode).
The trap lies in confusing the roles of Dicer and Argonaute, and forgetting that the nematode merely ingests the pre-formed dsRNA rather than transcribing it.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Biotechnology and Its Applications - Class 12 |
| Concept | RNA Interference (RNAi) Mechanism |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |