For the following crosses, determine as accurately as possible the genotypes of each parent, the parent in whom nondisjunction occurs, and whether nondisjunction takes place in the first or second meiotic division.

Both color blindness and hemophilia, a blood-clotting disorder, are X-linked recessive traits. Capital letters represent wild-type alleles, lowercase letters represent mutant alleles. In each case, assume the parents have normal karyotypes.

Part A
A man and a woman who each have wild-type phenotypes have a son with Klinefelter syndrome (XXY) who has hemophilia. What are the genotypes of the parents?
Select at least two answers (one genotype for the father and one genotype for the mother). If there is more than one possible genotype for a parent, select all that apply.
Select at least two answers (one genotype for the father and one genotype for the mother). If there is more than one possible genotype for a parent, select all that apply.
XH Y
X hY
XH XH
XH Xh
Xh X h

Part B
For the cross in Part A, in which parent and during what meiotic division might nondisjunction have occurred?
Select all that apply.
Select all that apply.
maternal meiosis I
maternal meiosis II
paternal meiosis I
paternal meiosis II

Part C
A man who is color blind and a woman who is wild type have a son with Jacob syndrome (XYY) who has hemophilia. What are the genotypes of the parents?
Select at least two answers (one genotype for the father and one genotype for the mother). If there is more than one possible genotype for a parent, select all that apply.
Select at least two answers (one genotype for the father and one genotype for the mother). If there is more than one possible genotype for a parent, select all that apply.
X CY
X cY
XH XH
XH Xh
Xh X h

Part D
For the cross in Part C, in which parent and during what meiotic division might nondisjunction have occurred?
Select all that apply.
Select all that apply.
maternal meiosis I
maternal meiosis II
paternal meiosis I
paternal meiosis II

Part E
A color-blind man and a woman who is wild type have a daughter with Turner syndrome (XO) who has normal color vision and blood clotting. What are the genotypes of the parents?
Select at least two answers (one genotype for the father and one genotype for the mother). If there is more than one possible genotype for a parent, select all that apply.
Select at least two answers (one genotype for the father and one genotype for the mother). If there is more than one possible genotype for a parent, select all that apply.
X CY
X cY
X CXC
X CXc
X cXc

Part F
For the cross in Part E, in which parent and during what meiotic division might nondisjunction have occurred?
Select all that apply.
Select all that apply.
maternal meiosis I
maternal meiosis II
paternal meiosis I
paternal meiosis II

Part G
A man who is color blind and has hemophilia and a woman who is wild type have a daughter with triple X syndrome (XXX) who has hemophilia and normal color vision. What are the genotypes of the parents?
Select at least two answers (one genotype for the father and one genotype for the mother). If there is more than one possible genotype for a parent, select all that apply.
Select at least two answers (one genotype for the father and one genotype for the mother). If there is more than one possible genotype for a parent, select all that apply.
X CHY
X ChY
X cHY
X chY
XCH XCH
X ChXCh
X cHXcH
X ChX CH
X ChX cH
X chX ch
Part H
For the cross in Part G, in which parent and during what meiotic division might nondisjunction have occurred?
Select all that apply.
Select all that apply.
maternal meiosis I
maternal meiosis II
paternal meiosis I
paternal meiosis II