Genetics worksheet with answers

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

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

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 affected daughter.

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

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 unaffected son.

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

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

In a population of 2000 in Hardy–Weinberg equilibrium, 16% show a recessive trait. How many individuals N are expected to be homozygous dominant?