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 has purple flowers?

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

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

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

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 tall plants (dominant) or short plants. Click the one cell for an offspring that is shows both wrinkled seeds and short 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

A recessive condition affects 4% of a population in Hardy–Weinberg equilibrium. What fraction f of the population are carriers (heterozygous)?