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Question #45942
The Question
Agrobacterium tumefaciens is widely known as a 'natural genetic engineer' due to its ability to induce crown gall tumors in dicotyledonous plants. This pathogenic interference fundamentally disrupts the plant's normal growth rate quantification. Which of the following statements is INCORRECT regarding the physiological and molecular mechanism of this tumorigenesis?
Options
- A.
The integrated T-DNA contains oncogenes that encode enzymes, forcing the host cell to endogenously overproduce specific phytohormones.
- B.
The pathogen induces hyper-proliferation by directly secreting massive quantities of auxins and cytokinins into the host's intercellular spaces.
- C.
The transformed cells exhibit localized, uncontrolled exponential growth that is biologically disconnected from the plant's normal developmental checkpoints.
- D.
The T-DNA integrates into the host's nuclear genome, also directing the transformed cells to synthesize opines for the pathogen's use.
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
Auxin/Cytokinin Ratio|T-DNA Integration|Crown Gall
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often confuse pathogenic interference via 'chemical secretion' (exogenous delivery of hormones/toxins) with 'genetic transformation' (hijacking the host's biosynthetic machinery via DNA transfer).
While Auxin and Cytokinin are responsible for the tumor, their source in crown gall disease is the genetically modified host cell, not direct secretion by the bacterium.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Plant Growth and Development - Class 11 |
| Concept | Growth Rate Quantification |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |