[Campbell Biology P.1110] Wilhelm Roux's earlier experiment involved killing one blastomere, ... | Practice Question

Wilhelm Roux's earlier experiment involved killing one blastomere, resulting in a "half-embryo," which differed from Spemann's control where two separated blastomeres each formed a normal embryo. Based on the provided text, what is the most likely reason for the difference in results?

  • A: Roux's experiment involved a different amphibian species with distinct developmental properties.
  • B: Spemann's separation technique allowed for the redistribution of critical cytoplasmic determinants before development.
  • C: The remnants of the dead blastomere in Roux's experiment contained cytoplasmic determinants that interfered with or suppressed the normal development of the surviving blastomere.
  • D: Roux's needle insertion itself introduced harmful substances that caused the abnormality.

Explanation

The "WHAT IF?" section states that the "presence of molecules in the dead cell" might explain why Roux's result differed from Spemann's control. This suggests that the dead blastomere, despite being non-living, still retained crucial cytoplasmic determinants that, by their mere presence or perhaps by being in an abnormal, non-functional state , hindered or altered the normal developmental process of the surviving blastomere, preventing it from compensating and forming a complete embryo. In Spemann's control, the blastomeres were physically separated after normal division, allowing each to develop independently without interference from a dead cell's contents.