Final Answer:
1. X<sup>N</sup>X<sup>n</sup> and X<sup>N</sup>Y
2. white eyes: male — X<sup>n</sup>Y; red-eyed female (heterozygous): X<sup>N</sup>X<sup>n</sup>; white-eyed female: X<sup>n</sup>X<sup>n</sup>
3. Offspring genotypes: X<sup>N</sup>X<sup>n</sup>, X<sup>n</sup>X<sup>n</sup>, X<sup>N</sup>Y, X<sup>n</sup>Y
→ white eyes: 2 (X<sup>n</sup>X<sup>n</sup>, X<sup>n</sup>Y); red-eyed: 2 (X<sup>N</sup>X<sup>n</sup>, X<sup>N</sup>Y)
4. Parents: X<sup>n</sup>X<sup>n</sup> (white-eyed female) × X<sup>N</sup>Y (red-eyed male)
Offspring: X<sup>N</sup>X<sup>n</sup> (red-eyed female), X<sup>n</sup>Y (white-eyed male)
→ white eyes: 1 (male); red eyes: 1 (female)
5. Parents: X<sup>n</sup>X<sup>n</sup> (white-eyed female) × X<sup>n</sup>Y (red-eyed male) — *but red-eyed male must be X<sup>N</sup>Y*, so likely typo; assuming red-eyed male = X<sup>N</sup>Y, then cross is X<sup>n</sup>X<sup>n</sup> × X<sup>N</sup>Y → same as #4
However, if the male is truly red-eyed and genotype given as X<sup>n</sup>Y, that’s impossible — so correct cross is X<sup>n</sup>X<sup>n</sup> × X<sup>N</sup>Y
Offspring: X<sup>N</sup>X<sup>n</sup>, X<sup>n</sup>Y → white eyes: 1 (male); red eyes: 1 (female)
6. Hemophilia is X-linked recessive. Females need two copies (X<sup>h</sup>X<sup>h</sup>) to have disease. Males with one copy (X<sup>h</sup>Y) get it.
If 100 males tested, and 20 have hemophilia → 20 are X<sup>h</sup>Y
So frequency of X<sup>h</sup> allele = 20/100 = 0.2
In females, probability of X<sup>h</sup>X<sup>h</sup> = (0.2)² = 0.04 → 4% of 200 females =
8 females
Males who won’t get it: those with X<sup>H</sup>Y = 100 − 20 =
80 males
But since the question asks only for final answers in blanks:
For #3: white eyes:
2, red eyes:
2
For #4: white eyes:
1, red eyes:
1
For #5: white eyes:
1, red eyes:
1
For #6: females with disease:
8, males without disease:
80
So filling the blanks as expected:
3. white eyes:
2, red eyes:
2
4. white eyes:
1, red eyes:
1
5. white eyes:
1, red eyes:
1
6. females with disease:
8, males without disease:
80
Parent Tip: Review the logic above to help your child master the concept of genetics x linked genes worksheet answers.