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 tall plants and is dominant over t, which gives short plants. Click the cell for an offspring that has tall plants 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 unaffected 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

red-green colour blindness is X-linked recessive (allele b). A carrier mother, X^BX^b, has children with an affected father, X^bY. The mother's gametes run down the side. Click the cell for a carrier daughter.

1. 1X^B × X^b
2. 2X^B × Y
3. 3X^b × X^b
4. 4X^b × Y

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

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

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