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Question #46546
The Question
Metastasis is the most feared property of malignant tumors, representing a catastrophic regulatory failure of the cell cycle and tissue boundaries. Which of the following best explains the molecular and genetic basis for the 'loss of contact inhibition' that facilitates this process?
Options
- A.
The activation of cellular oncogenes (c-onc) upregulates E-cadherins, which strengthens cell-cell junctions and forces the tumor mass to expand into adjacent tissues.
- B.
The activation of proto-oncogenes (c-onc) into oncogenes is accompanied by the downregulation of E-cadherins, permitting cellular detachment and vascular infiltration.
- C.
The transformation is driven by the activation of tumor suppressor genes, which bypasses the cell cycle checkpoints and induces metastasis.
- D.
The loss of contact inhibition is a defining feature of benign tumors, physically restricting their rapid clonal expansion to a localized anatomical capsule.
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
Cell_Cycle|Contact_Inhibition|Proto-oncogenes
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize 'loss of contact inhibition' without understanding its structural basis (loss of cell adhesion/cadherins).
Furthermore, they frequently confuse the direction of genetic changes in cancer.
The trap in Option A tests if they know that metastasis requires decreased adhesion (downregulation of E-cadherins) to leave the primary site.
Option C tests the common misconception regarding tumor suppressor genes (they must be inactivated, not activated, to cause cancer), while Option D tests the clinical distinction between benign and malignant tumors.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Human Health and Disease - Class 12 |
| Concept | Metastasis |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |