Genetics worksheet with answers

Two Tt parents are crossed. T gives round seeds and is dominant over t, which gives wrinkled seeds. Click the cell for an offspring that has round seeds and is homozygous.

1. 1T × t
2. 2T × T
3. 3t × t
4. 4t × T

Two Rr parents are crossed. R gives purple flowers and is dominant over r, which gives white flowers. Click the cell of the Punnett square for an offspring with white flowers.

1. 1R × r
2. 2R × R
3. 3r × r
4. 4r × R

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

haemophilia is X-linked recessive (allele h). A carrier mother, X^HX^h, has children with an unaffected father, X^HY. The mother's gametes run down the side. Click the cell for an unaffected son.

1. 1X^H × X^H
2. 2X^H × Y
3. 3X^h × X^H
4. 4X^h × Y

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

A recessive condition affects 1% of a population in Hardy–Weinberg equilibrium. What fraction f of the population are carriers (heterozygous)?