In man, the determination of sex depends upon whether the male sperm carries an "X" chromosome (resulting in a female) or a "Y" chromosome (resulting in a male). In other words, body cells of females carry two X chromosomes, and those of the males carry one X and one Y. During meiotic division, the egg of the female must of necessity carry one X, whereas segregation of the X and Y in spermatogenesis results in some sperm that are Y bearing, and others that are X bearing. One human abnormality, called red-green color blindness, is the result of a recessive allele (Xb) carried on the X chromosome. The dominant allele (XB) produces normal vision. There is no copy of this gene on the Y chromosome. Consequently, the genotypes XBXB, XBXb, and XbXb are possible in females, but a male must be either XBY or XbY.
Working theoretically, answer the following questions:
a. Is it possible for a female to be color-blind?
b. Can two persons with normal vision produce a color-blind daughter?
c. Can two persons with normal vision produce a color-blind son?
d. Can two color-blind parents produce a child with normal vision?