When division of the zygote reaches the eight-cell stage and the planes of cleavage of the upper four cells line up with those of the bottom four cells so that two tiers of cells result, one directly above the other, the type of cleavage is called

A. direct cleavage.
B. spiral cleavage.
C. indirect cleavage.
D. protostome cleavage.
E. radial cleavage.

Which statement describes the punctuated equilibrium theory?

16 select the correct answer from each drop-down menu. sharks, whales, and dolphins share similar features such as body shape and the position of fins. hoy while whales and dolphins have lungs. these differences indicate that the organisms share a comme whales also possess a vestigial pelvic bone. the presence of the pelvis bone may indicate that whales reset next

Glands that the body deal with stress and respond to emergencies.