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Question #45346
The Question
A researcher genetically engineers a Citrus plant to be heterozygous (R/r) for a dominant selectable marker (antibiotic resistance). The gene of interest was inserted at the unique cloning site of the vector. This transgenic maternal plant is then pollinated by a non-transgenic, wild-type (r/r) plant. The resulting seeds exhibit polyembryony. Which of the following statements is INCORRECT regarding the seed structures and the embryos within?
Options
- A.
All adventive embryos develop mitotically from the maternal nucellus and will uniformly express antibiotic resistance.
- B.
The zygotic embryo is formed via syngamy and has a 50% probability of being sensitive to the antibiotic, allowing its distinction from apomictic clones.
- C.
The perisperm represents persistent nucellus and is diploid, whereas the pericarp develops from the ovary wall; both are strictly maternal and do not show genetic segregation.
- D.
The selectable marker acts as the specific recognition sequence for restriction endonucleases, ensuring that adventive embryos inherit the recombinant DNA without meiotic segregation.
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
Nucellus|Tissue_Culture|Recombinant_DNA
Why This Question Is Tricky
Common Mistakes
The 'Conceptual Pivot' lies in distinguishing the distinct roles of biotechnology tools (Selectable Marker vs.
Cloning Site) and understanding the true biological cause of clonal inheritance in polyembryony.
Students often memorize that 'selectable markers help identify clones' (in bacteria) and falsely extend this to mean the marker causes or ensures the clonal inheritance in plants, missing that adventive embryony (a form of apomixis) is the actual mechanism preventing meiotic segregation.
Furthermore, they frequently confuse the cloning site (where REs cut) with the selectable marker (which screens for transformants).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Sexual Reproduction in Flowering Plants - Class 12 |
| Concept | Polyembryony Mechanisms |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |