Genetics worksheet with answers

Two Bb parents are crossed. B gives yellow seeds and is dominant over b, which gives green seeds. Click the cell for an offspring that has yellow seeds and is homozygous.

1. 1B × B
2. 2B × b
3. 3b × B
4. 4b × b

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 white flowers?

red-green colour blindness is X-linked recessive (allele b). A carrier mother, X^BX^b, has children with an affected 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

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

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

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