Genetics worksheet with answers

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

Tall (A) is dominant over short (a), and round seeds (B) over wrinkled (b). The genes are on different chromosomes. For the cross AaBb × Aabb, what is the probability P that an offspring is short, wrinkled seeds?

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 affected son.

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

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 shows both wrinkled seeds and 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

A recessive condition affects 9% of a population in Hardy–Weinberg equilibrium. What fraction f of the population are carriers (heterozygous)?