4. What is the function of the yolk sac? (3 marks) 5. Which is the extraembryonic membrane whose function is to store nitrogen wastes of the embryo? 6. What is the cell division process directly related to the embryonic growth? 7. Participation of more than one spermatozoon in fertilization is called __ 8. Extra sperm which succeed in passing through the zona pellucida into the perivitelline space are called __ 9. How the transport of ovum in the oviduct is facilitated? (3 marks) 10. Explain the mechanisms underlying the blocks to polyspermy?

4. The function of the yolk sac is to provide early nourishment to the embryo and to form the first red blood cells and platelets.<br /><br />5. The extraembryonic membrane that functions to store nitrogen wastes of the embryo is the allantois.<br /><br />6. The cell division process directly related to the embryonic growth is mitosis.<br /><br />7. The participation of more than one spermatozoon in fertilization is called polyspermy.<br /><br />8. Extra sperm that succeed in passing through the zona pellucida into the perivitelline space are called polyspermy.<br /><br />9. The transport of the ovum in the oviduct is facilitated by ciliary action, peristaltic contractions, and muscular contractions of the oviduct walls.<br /><br />10. The mechanisms underlying the blocks to polyspermy include the formation of a fertilization envelope, the release of cortical granules, and the activation of ion channels that lead to changes in the zona pellucida.