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 is heterozygous (Aa)?

Two Bb parents are crossed. B gives tall plants and is dominant over b, which gives short plants. Click the cell for an offspring that has tall plants and is homozygous.

1. 1B × B
2. 2B × b
3. 3b × B
4. 4b × 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 × 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 unaffected father, X^BY. The mother's gametes run down the side. Click the cell for an affected son.

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

In a population of 2000 in Hardy–Weinberg equilibrium, 4% show a recessive trait. How many individuals N are expected to be homozygous dominant?

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 homozygous for black fur and for round 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