Genetics worksheet with answers

Two Rr parents are crossed. R gives black fur and is dominant over r, which gives white fur. Click the cell for an offspring that has black fur and is homozygous.

1. 1R × R
2. 2R × r
3. 3r × R
4. 4r × r

Two Bb parents are crossed. B gives black fur and is dominant over b, which gives white fur. Click the cell of the Punnett square for an offspring with white fur.

1. 1b × b
2. 2b × B
3. 3B × b
4. 4B × B

Duchenne muscular dystrophy is X-linked recessive (allele d). A carrier mother, X^DX^d, has children with an unaffected father, X^DY. The mother's gametes run down the side. Click the cell for a carrier daughter.

1. 1X^d × X^D
2. 2X^d × Y
3. 3X^D × X^D
4. 4X^D × Y

haemophilia is X-linked recessive (allele h). A carrier mother, X^HX^h, has children with an affected father, X^hY. The mother's gametes run down the side. Click the cell for a carrier daughter.

1. 1X^H × Y
2. 2X^H × X^h
3. 3X^h × Y
4. 4X^h × X^h

A recessive condition affects 1 in 1600 of a population in Hardy–Weinberg equilibrium. What fraction f of the population are carriers (heterozygous)?

Two AaBb parents are crossed. Gene A gives tall plants (dominant) or short plants; gene B gives black fur (dominant) or white fur. Click the one cell for an offspring that is homozygous for tall plants and for black fur.

1. 1Ab × AB
2. 2Ab × aB
3. 3Ab × ab
4. 4Ab × Ab
5. 5aB × AB
6. 6aB × aB
7. 7aB × ab
8. 8aB × Ab
9. 9ab × AB
10. 10ab × aB
11. 11ab × ab
12. 12ab × Ab
13. 13AB × AB
14. 14AB × aB
15. 15AB × ab
16. 16AB × Ab