[Campbell Biology P.1100] According to the provided text and Figure 47.10, which event marks ... | Practice Question

According to the provided text and Figure 47.10, which event marks the initial step of gastrulation in a frog embryo?

  • A: The blastopore extends around both sides of the embryo, forming a circle.
  • B: Cells on the dorsal side invaginate to form a small indented crease, the blastopore.
  • C: The blastocoel shrinks and eventually disappears.
  • D: The archenteron forms and grows.

Explanation

According to the text, 'Gastrulation begins when cells on the dorsal side invaginate to form a small indented crease, the blastopore' step 1 . This is the very first event described as initiating gastrulation.