Question 1).

A black mouse mates with a brown mouse and all the offspring are black.

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1. Write all the possibilities of the genotypes of the parents. Draw cross diagrams to show all the possibilities of parents and offspring.
2. Why are no brown offspring produced? Explain your answer.
3. Describe the genotype of the parents and the offspring. (Use words such as "heterozygous" or "homozygous" and "dominant" or "recessive".)

Question 2).

If two of the black offspring from question 1 mate with each other, what kind of offspring would you expect and in what proportions? Draw a cross diagram to illustrate what happens and express the proportions in percent.

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Question 3).

In human beings the gene for brown eyes is dominant over the gene for blue eyes. A brown-eyed man marries a blue-eyed woman and they have five children. Three of the children have brown eyes and two have blue eyes.

1. What are the genotypes of the mother, the father, and the children? Explain how you arrive at your answer.
2. Draw cross diagrams to show your eye color and the possibilities of your parents. Circle your genotype on the cross diagrams.  If you are not sure of your parents' genotypes for any reason, give all the genotypes that they could possibly be. 

Question 4).

An albino is a person who has no pigment in the skin and so is very pale. This condition is caused by a recessive gene. An albino man marries a woman who is not an albino, but one of her parents was an albino.

1. How likely is it that their first child will be an albino? Give your reasons in full.
2. Certain individuals in this family are 'carriers'. Which ones are carriers and what does this word mean?