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 Tt parents are crossed. T gives purple flowers and is dominant over t, which gives white flowers. Click the cell of the Punnett square for an offspring with white flowers.

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 affected father, X^bY. The mother's gametes run down the side. Click the cell for a carrier daughter.

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

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

A recessive condition affects 1 in 2500 of a population in Hardy–Weinberg equilibrium. What fraction f of the population are carriers (heterozygous)?

In a population of 10000 in Hardy–Weinberg equilibrium, 1% show a recessive trait. How many individuals N are expected to be homozygous dominant?