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 Aa parents are crossed. A gives tall plants and is dominant over a, which gives short plants. Click the cell of the Punnett square for an offspring with short plants.

1. 1A × A
2. 2A × a
3. 3a × A
4. 4a × a

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 an unaffected son.

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

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

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

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

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