[Campbell Biology P.1110] Based on Hans Spemann's experiment regarding the gray crescent's di... | Practice Question

Based on Hans Spemann's experiment regarding the gray crescent's distribution and the developmental potential of the first two daughter cells, which of the following conclusions is most accurate?

  • A: The gray crescent is the sole determinant for all embryonic development.
  • B: Uneven distribution of the gray crescent material between the two blastomeres results in abnormal embryonic development.
  • C: The presence of the gray crescent ensures that both blastomeres always develop into complete, normal embryos.
  • D: The gray crescent primarily determines the formation of the "belly piece" structure in normal development.

Explanation

Spemann's experiment showed that when the gray crescent was unevenly distributed, the blastomere receiving less or none of it developed into an abnormal "belly piece" embryo, while the blastomere receiving sufficient gray crescent material developed normally. This demonstrates that the gray crescent's material is essential for normal embryonic development, and its uneven distribution leads to abnormal outcomes.