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 black fur and is dominant over r, which gives white fur. Click the cell for an offspring that has black fur and is homozygous.

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

haemophilia is X-linked recessive (allele h). A carrier mother, X^HX^h, has children with an affected father, X^hY. The mother's gametes run down the side. Click the cell for an affected son.

1. 1X^H × X^h
2. 2X^H × Y
3. 3X^h × X^h
4. 4X^h × 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 short, round seeds?

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

In a population of 1000 in Hardy–Weinberg equilibrium, 1 in 1600 show a recessive trait. How many individuals N are expected to be homozygous dominant?