110 CHAPTER 14 



14.4. What explanations can you offer, other than those presented, which may pertain to 

 the shift in sex ratio with age of human parents? 



14.5. No YO human beings are known. Is this chromosomalconstitution considered 

 lethal? Why? 



14.6. List the types of human zygotes formed following maternal nondisjunction of the 

 X chromosome. What are the phenotypes expected for each of the zygotes these 

 may form in turn? 



14.7. List specific causes for the production of abnormal sex types in human beings. 



14.8. How can you account for the fact that one XO individual is known who has had a 

 successful pregnancy, whereas most known XO's are sterile? 



14.9. Discuss the general applicability of the chromosomal balance theory of sex determi- 

 nation. 



14.10. In Drosophila, why are gynanders not intersexes? Is this true in man also? Explain. 



14.11. What chromosomal constitution can you give for a triploid human being who is 

 "male"? "female"? 



Which of these chromosomal constitutions would you expect to deviate most from 

 its normal sex? Explain. 



14.12. A non-hemophilic man and woman have a son who proves to be a hemophilic 

 Klinefelter male. Describe the chromosomal content and genotypes of all three 

 individuals mentioned. 



