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Question #46600
The Question
A biotechnologist inserts a kanamycin-resistance gene into the nod operon of a Rhizobium strain to track its colonization in a leguminous host. When this transgenic strain is inoculated into the host's rhizosphere, which of the following is the most likely outcome?
Options
- A.
Root hair curling will not occur, and the host plant will reject the bacteria by mounting a defense response.
- B.
The bacteria will successfully form an infection thread but will be destroyed by host immunity in the cortical cells.
- C.
The host will form empty pseudo-nodules lacking leghemoglobin because the bacteria cannot differentiate into bacteroids.
- D.
Symbiosis will proceed normally, but the nitrogenase enzyme will be inactive due to the disruption of nif genes.
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
Symbiotic Nitrogen Fixation|Selectable Marker vs Cloning Site|Rhizobium
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Distinguishing between 'nod' genes (responsible for host recognition and physical entry) and 'nif' genes (responsible for nitrogen fixation).
A common misconception is that any transgenic modification only affects the final nitrogen-fixing ability, whereas disrupting the 'nod' operon halts the symbiosis at the very first step (root hair curling), turning a mutualist into a perceived pathogen.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Microbes in Human Welfare - Class 12 |
| Concept | Symbiotic Nitrogen Fixation |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |