Embryology Worksheet Biology 100C 1. An organism’s development is largely determined by: A. B.
2. The main function of fertilization is the joining of a sperm cell and an egg cell forms a single cell called a . 3. Another key function of fertilization is .
4. Why can the development of a sea urchin tell us something about our own development?
5. What is the “acrosomal reaction”?
6. What is the “acrosomal process”?
7. Where is the “vitelline membrane” located in relation to the plasma membrane of the egg?
8. The “acrosomal reaction” leads to:
9. Fusion of the sperm and egg cell membranes causes ion channels to open in the egg cell’s plasma membrane, allowing Na+ ions to flow into the egg cell and change the membrane potential. This depolarization of the membrane potential is called the because it . 10. The fusion of sperm and egg also triggers a signal-transduction pathway that causes the egg’s endoplamic reticulum to release Ca++ into the cytoplasm. This brings about a reaction called the . 11. Explain the cortical reaction.
12. The result of the cortical reaction is the production of an envelope or membrane called the , which .
13. The production of the envelope above functions as a 14. Is it possible to activate an egg to begin dividing without fertilization? 15. If the answer to #14 is yes, the development is by .
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16. To get into a mammal egg a sperm cell must pass through several outer layers of cells called , through the extracellular matrix of the egg called the and finally through the . 17. The slow block to polyspermy in mammals is due to changes in the . 18. is a succession of rapid cell divisions that follow fertilization.
19. Does the embryo enlarge during the activity in #18? 20. What is the function of the activity in #18?
21. Yolk is generally more concentrated at one pole of the fertilized egg, called the while the opposite pole, called the has the lower concentration of yolk. 22. Continued cleavage produces a solid ball of cells called a 23. The structure in #22 turns into a hollow ball of cells called a the hollow center of this structure is called the 24. A dramatic rearrangement of the cells of the blastula is called 25. The structure formed through the action in #24 is called a 26. How many embryonic tissue layers are present in a gastrula? Name them. . . and . .
27. What is the archenteron? What is the blastopore?
28. What structures in the adult animal are derived from each of the three embryonic germ layers?
Ectoderm:
Mesoderm:
Endoderm:
29. Which organs are the first to develop in a frog or other chordate animal?
30. Explain how the “neural tube” and brain come to lie below the outer layer of the animal. (use Figure 47.11 and text for information)
31. Name the four “extraembryonic membranes”.
32. What is the function of each of the extraembryonic membranes?
33. In embryological development the term “Induction” means:
34. The response to an inductive signal is usually:
35. How do the Notochord and the Dorsal Hollow Nerve Chord in a Chordate relate to one another in terms of “Induction”?