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 of the Punnett square for an offspring with white fur.

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 is heterozygous (Aa)?

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 × 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 affected father, X^dY. The mother's gametes run down the side. Click the cell for an affected daughter.

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

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

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 5000 in Hardy–Weinberg equilibrium, 1 in 400 show a recessive trait. How many individuals N are expected to be homozygous dominant?