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Question #46421
The Question
Normal cells exhibit 'contact inhibition', a property lost in cancer cells, leading to uncontrolled biogenesis and tumor formation. In the context of NCERT's description of oncogenic transformation and cell cycle regulation, which of the following statements is CORRECT regarding the molecular mechanism of this autonomous proliferation?
Options
- A.
It is caused by the activation of proto-oncogenes into oncogenes, which overrides the G1/S checkpoint and prevents the cell from entering the G0 phase.
- B.
It occurs when cellular oncogenes (c-onc) are inactivated by carcinogens, leading to the failure of the G2/M checkpoint and rapid cytokinesis.
- C.
It is driven by the overexpression of tumor suppressor genes, which causes the loss of contact inhibition and continuous DNA replication.
- D.
It results from the conversion of viral oncogenes (v-onc) into proto-oncogenes, forcing the cell to bypass the S phase and divide continuously.
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
Oncogenes vs Proto-oncogenes|Apoptosis|Cell Cycle
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students frequently confuse the activation/inactivation states of the two major cancer gene classes.
The trap relies on understanding that Proto-oncogenes act like a 'stuck gas pedal' (require activation to become oncogenes), while Tumor Suppressor Genes act like 'cut brakes' (require inactivation).
Additionally, it tests the integration of Class 12 'Human Health and Disease' (c-onc, contact inhibition) with Class 11 'Cell Cycle' (G1/S checkpoint, G0 phase).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Evolution - Class 12 |
| Concept | Abiogenesis vs. Biogenesis |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |