502 THE BRIDGE OF LIFE 



5. How does meiosis differ from ordinary mitosis? 



6. How does spermatogenesis differ from oogenesis? 



7. Man has 48 chromosomes as his normal diploid number. How many 

 chromosomes would there be in : a primary spermatocyte, an egg, a cell of the skin, 

 a secondary spermatocyte, a polar body, a sperm ? 



8. Why are eggs much larger than sperms ? 



9. What prevents more than one sperm from entering an egg in fertilization? 



10. There have been a few cases where eggs, which normally are fertilized, have 

 been induced to develop experimentally without fertilization. What is there about 

 the egg that makes this possible? 



11. Is it conceivable that a sperm could ever be induced to develop into an 

 embryo without an egg ? Give reasons for your answer. 



12. In surveying your ancestry, suppose you find that George Washington was 

 your great, great, great, great grandfather. By the law of averages, what proportion 

 of your genes would be expected to have come to you from this illustrious father of 

 our country? 



