Genetics worksheet with answers

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

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

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)?

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?

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 unaffected son.

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

In a population of 2000 in Hardy–Weinberg equilibrium, 9% show a recessive trait. How many individuals N are expected to be homozygous dominant?

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

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