1. Another name for a fertilized egg is a . 2. Name the cell division process (starts with the letter “m”) in which the fertilized eggs develop into a multicellular embryo (ie. 2 cell, 4 cell, 8 cell, etc).
3. The embryonic stage referred to as a hollow ball of cells is called the and its central cavity is the .

4. Name the embryonic stage where cells are moving inward toward the central cavity (invagination) forming the beginning of the primitive digestive system or archenteron (arch (G) = primitive; enteron (G) = gut)).

5. Stoma is (G) meaning mouth and deutero is (G) for 2nd. Therefore, deuterostomes are organisms in which the 2nd embryonic opening becomes the of the organism and the 1st opening or blastopore becomes the .

6. Name the 2 major phyla that are deuterostomes: and

7. Proto is (G) for first; therefore, in organisms that are protostomes the 1st opening becomes the . Arthropods, 80% of animals, are protostomes.

8. Ectoderm develops into the and ; mesoderm develops into and endoderm develops into.