Cancer and uncontrolled cell division Transitional Reasoning Practice

Questions

1. 1.

   A researcher cultures two mammalian cell lines, designated Line X and Line Y, in vitro under identical physiological conditions. Cell Line X ceases division upon forming a single, confluent monolayer on the culture dish surface and halts at the G1 checkpoint unless serum-derived growth factors are supplied. In contrast, Cell Line Y continues to divide after reaching confluency, piling up into multi-layered aggregates, and proceeds through the cell cycle even when external growth factors are completely depleted from the medium. Based on these observations, which statement most accurately evaluates the cell cycle regulation in these two cell lines?

   • A) Cell Line X demonstrates anchorage-independent growth characteristic of malignant cells, whereas Cell Line Y exhibits normal density-dependent inhibition at the G2/M boundary.
   • B) Cell Line Y has lost density-dependent inhibition and external growth factor dependence, indicating impaired cell cycle checkpoint controls or self-sustained proliferative signaling typical of cancer cells.
   • C) Cell Line X bypasses the requirement for cyclin-dependent kinase activation entirely, while Cell Line Y relies strictly on paracrine signals to prevent apoptotic clearance.
   • D) Both cell lines retain functional contact inhibition, but Cell Line Y executes an adaptive metabolic shift that accelerates progression through the spindle assembly checkpoint.

Answers and step-by-step solutions appear after you finish the test.