Genetics worksheet with answers

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)?

Two Tt parents are crossed. T gives tall plants and is dominant over t, which gives short plants. Click the cell of the Punnett square for an offspring with short plants.

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

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 unaffected son.

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

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 tall, round seeds?

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 wrinkled seeds and is homozygous for yellow 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

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