Genetics worksheet with answers

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

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)?

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

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 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

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