1. Define each of the following terms and give an example.
   1. Simple (complete) dominance =

1. Incomplete dominance =

1. Codominance =

1. Monohybrid cross =

1. Dihybrid cross =

1. Sex-linked trait =

Simple Dominance with one gene:

1. A certain moth species can have either a long (L) or short (l)proboscis.
   1. If you cross a true-breeding long with a true-breeding shortproboscis moth in the P generation, what will be the genotypes andphenotypes of the F1 generation?

1. 1. If you cross two of the F1 offspring together, what will be thegenotypes and phenotypes of the F2 generation? Give the fraction ofthe offspring that will have each genotype and phenotype.
2. Roberts’ syndrome causes children to be born with misshapenbones in their faces, skulls, and limbs. Roberts’ syndrome isinherited on a recessive allele, while the dominant allele codesfor normal bone shape.
   1. If a carrier for the Roberts’ allele marries someone who ishomozygous dominant for the normal allele, what are the chancesthat their child will be born with Roberts’ syndrome?

1. If both parents were carriers, what would be the likelihoodthat their child would get Roberts’ syndrome?

1. The polled (meaning hornless) trait in cattle is dominant, thehorned trait is recessive. A rancher has a polled bull (male) andmates the same bull to three cows (female). Cow A is horned andproduces a polled calf. Cow B is horned and produces a horned calf.Cow C is polled and produces a horned calf. What are the genotypesof the four parents and their calves?

Simple Dominance with 2 genes

1. A gene in cats causes them to be black (dominant) or brown(recessive). A second gene causes cats to be agouti (have stripeson their hairs) or non-agouti (solid colored hairs).
   1. If you did a dihybrid cross between two black haired agouticats, what fraction of the offspring would be expected to have eachphenotype?

1. If a dihybrid black agouti cat mated with a brown cat that washeterozygous for the agouti gene, what fraction of the offspringwould be expected to have each phenotype?

Test Cross

1. In mythical dragons, the ability to breath fire (F) is dominantover not being able to breathe fire (f). If you have afire-breathing dragon and want to know whether it is homozygous orheterozygous, what could you do to find out? Explain how you woulddo the experiment.

1. In moths, having a long proboscis is dominant over having ashort proboscis. You’re trying to figure out whether a particularfemale moth with a long proboscis is pure or a hybrid, so you crossit with a male moth that has a short proboscis. Half the offspringhave long and half have short proboscii. What was the genotype oftheir mother?

1. In cats, black fur is dominant over brown fur. You have a blackcat and you want to know whether it is true breeding for its blackfur color, so you mate it with a brown cat. All 10 of their kittensare white. What was the genotype of your parent black cat? Can yoube absolutely sure?

Incomplete Dominance

1. In rabbits, alleles for short fur (S) and long fur (L) areincompletely dominant. Hybrids have medium length fur. If you did amonohybrid cross with these rabbits, what ratio of short fur:medium fur: long fur would you see in the offspring?
2. In Andalusian fowl (similar to chickens), if you mate a truebreeding white fowl with a true breeding black fowl, all theoffspring will be blue. If you were to mate a blue fowl with awhite fowl, what fraction of the offspring would be blue?

1. In cats, a particular gene determines whether the cat has whitepatches on top of its other color(s). Homozygous dominant cats aremore than half white. Hybrid cats are less than half white, andhomozygous recessive cats have no white patches at all. If a catwith white only on its feet mated with a cat that had no white atall, what fraction of the kittens would have each genotype andphenotype?

Codominance

1. In some horses, hair color is determined by one gene with twoalleles. Homozygotes may be either red or white, and heterozygotesare roan (a mixture of red and white hairs). If you crossed tworoan horses together, what fraction of the offspring would beroan?

1. Human blood type alleles are codominant. Lucy has type A blood.Her daughter Jenna has type O blood. Jenna’s father Ralph has neverhad his blood type tested.

1. What is Lucy’s genotype?

1. What are the possible genotypes that Ralph could have?

1. A woman with type 0 blood gives birth to a baby with type 0blood. In a court case she claims that a man with type A blood isthe father of the child. Could he be the father? Show why he can orcannot. Can it be proven on this evidence alone that he is thefather?

Sex-linked genes

1. Hemophilia is a rare genetic disorder that results from adeficiency in blood clotting factors. When a person withouthemophilia gets a cut, the bleeding lasts for a short time and thenthe blood clots to form a scab. People with hemophilia have only1-5% of the blood clotting factors that other people have. Thus,when a hemophiliac gets a cut, it may continue to bleed for days orweeks, sometimes causing dangerous amounts of bloodloss.  Hemophiliacs have to do special exercises toprevent their muscles from tearing and producing internal bleeding,and they can take supplemental blood clotting factors, buthemophilia has no known cure. Hemophilia is caused by a recessiveallele that is located on the X chromosome.

If X^H is the allele fornormal blood clotting, and X^h is the allele forhemophilia, draw a cross between a normal father and a mother whois a carrier for hemophilia. Then list the percentages of offspringthat would get each genotype and phenotype.

1. Colorblindness is a sex-linked recessive trait. If a woman whowas a carrier married a man who was colorblind, what percentage oftheir children (males and females) would be colorblind?

1. For a male to be colorblind, does he have to get thecolorblindness allele from his mother, from his father, or both?For a female to be colorblind, does she have to get thecolorblindness allele from his mother, from his father, orboth?