67) The morula stage is part of which phase of embryonic development?

68) A zygote with animal and vegetal poles demonstrates what characteristic of some animal zygotes?

69) What are the three germ layers produced during gastrulation?

70) You are a substitute teacher in a high school biology lab class on the day the students are dissecting frogs. A particularly bright student happens to notice that the left adrenal gland is malformed in her frog. She asks if a problem in embryonic development could have caused that. Although there may be more than one reason, what might you propose as an explanation based on embryonic development?

71) You are a substitute teacher in a high school biology lab class on the day the students are dissecting fetal pigs. One student finds that his pig’s lungs, liver, pancreas, and digestive organs are either missing or small and malformed. The student scratches his head with his clean hand and says, “What went on here?” Although there may be more than one reason, what might you propose as an explanation based on embryonic development?

72) The earliest stage of development in which cells move to particular places in the developing embryo is ________.

73) During gastrulation in sea urchins, which forms first, the mouth or the anus?

74) The capacity of some embryonic cells to direct the development of other embryonic cells is called ________.