Genetics worksheet with answers

In pea plants, purple flowers (A) are dominant over white (a). A plant with genotype Aa is crossed with a plant with genotype Aa. What is the probability P that an offspring has white flowers?

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

1. 1T × t
2. 2T × T
3. 3t × t
4. 4t × T

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 an affected son.

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

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

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

In a population of 5000 in Hardy–Weinberg equilibrium, 1 in 1600 show a recessive trait. How many individuals N are expected to be homozygous dominant?