During the Early Part of the Cleavage Stage in Frog

Question

During the early part of the cleavage stage in frog development, the rapidly developing cells
A) skip the mitosis phase of the cell cycle.
B) skip the S phase of the cell cycle.
C) skip the G₁ and G₂ phases of the cell cycle.
D) rapidly increase the volume and mass of the embryo.
E) skip the cytokinesis phase of the cell cycle.

Accepted Answer

During the early part of cleavage stage, the cells of the embryo undergo rapid divisions without significant growth. This means that the cells do not have enough time to complete the G1 and G2 phases of the cell cycle, which are typically involved in cell growth and preparation for division. Therefore, option C is correct. The cells undergo mitosis and cytokinesis phases normally, as these are required for cell division. The rapid divisions lead to an increase in the number of cells, but not in the volume or mass of the embryo. Hence, options A, B, D, and E are incorrect.