Genetics worksheet with answers

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

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

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 unaffected father, X^BY. The mother's gametes run down the side. Click the cell for a carrier daughter.

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

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 affected son.

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

A recessive condition affects 1 in 10000 of a population in Hardy–Weinberg equilibrium. What fraction f of the population are carriers (heterozygous)?

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