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Question #47725
The Question
A wild-type Agrobacterium tumefaciens successfully infects a dicot plant, and its T-DNA integrates into the host's nuclear genome. However, no crown gall tumor develops. Molecular analysis reveals that the T-DNA integrated into a region of high chromatin stringency, and the plant mounted a robust cellular defense against the foreign transcripts. Which of the following statements regarding this host-pathogen interaction is INCORRECT?
Options
- A.
The high chromatin stringency at the integration site causes transcriptional silencing of the vir genes, thereby preventing tumor induction.
- B.
The host plant utilizes RNA interference (RNAi), a method of cellular defense present in all eukaryotes, to degrade the T-DNA transcripts.
- C.
The lack of tumor formation is directly attributed to the suppressed expression of T-DNA genes coding for auxin and cytokinin biosynthesis.
- D.
The post-transcriptional silencing of the pathogen's genes by the host involves the formation of double-stranded RNA (dsRNA) that prevents translation.
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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
Genetic_Code_Degeneracy|Alpha-1_Antitrypsin|Blue-White_Screening
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Differentiating between the genes transferred to the host (T-DNA: oncogenes and opine synthesis genes) and the genes required for the transfer process (vir genes).
Students frequently fall for the misconception that the entire Ti plasmid or the vir genes are integrated into the plant genome, failing to realize that vir genes operate exclusively within the bacterial cell prior to transfer.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Biotechnology : Principles and Processes - Class 12 |
| Concept | Blue-White Screening Mechanism |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |