Answer to Question 1
ANS: C
Muscular dystrophy is manifested primarily in males. Cystic fibrosis, neurofibromatosis, and Klinefelter syndrome are manifested in both males and females.
Answer to Question 2
ANS: B, C, D
The principles of X-linked recessive inheritance include: the trait is seen much more often in males than in females; the trait is never transmitted from father to son; the gene can be transmit-ted through a series of carrier females; the gene is passed from an affected father to all his daughters, who, as phenotypically normal carriers, transmit it to approximately half their sons, who are affected. X-linked recessive disorders can skip generations since it is a one in four chance.