Genetics worksheet with answers

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

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

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 purple flowers?

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 an unaffected son.

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

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 unaffected son.

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

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

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

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