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 purple flowers?

Two Bb parents are crossed. B gives round seeds and is dominant over b, which gives wrinkled seeds. Click the cell of the Punnett square for an offspring with wrinkled seeds.

1. 1B × B
2. 2B × b
3. 3b × B
4. 4b × b

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 affected son.

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

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

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

In a population of 10000 in Hardy–Weinberg equilibrium, 1 in 2500 show a recessive trait. How many individuals N are expected to be homozygous dominant?