A four o'clock plant with red flowers is crossed with a four o'clock plant with white flowers. Every seedling opens flowers that are the same shade of pink across the whole petal, and none is red or white. Which pattern of inheritance is this?

A red shorthorn bull is mated with a white shorthorn cow. Every calf's coat is a mixture of separate red hairs and separate white hairs, and a hand lens shows each hair is one solid color. Which pattern of inheritance does this show?

In Andalusian fowl, a black bird crossed with a splashed white bird produces chicks whose feathers are all a uniform slate blue. No chick is black and none is splashed white. Which pattern of inheritance accounts for the slate blue chicks?

A poultry keeper crosses a solid black hen with a solid white rooster. The chicks are erminette: each bird carries some feathers that are entirely black and some feathers that are entirely white. Which pattern of inheritance is operating?

Mendel crossed a true-breeding purple-flowered pea plant with a true-breeding white-flowered pea plant. Every F1 plant had purple flowers as deeply colored as the purple parent. Which pattern of inheritance is this?

In radishes, root shape is controlled by the alleles $R^L$ and $R^S$. A plant with long roots is crossed with a plant with round roots, and every offspring plant produces oval roots of one intermediate length. Which pattern is operating?

A chestnut horse is bred with a cream-colored cremello horse. The foal has a golden coat with a pale mane, a shade seen in neither parent, and every foal from this cross looks the same. Which pattern of inheritance produced the golden foal?

The gene for coat color in rabbits is found in four different forms in the population: C, $c^{ch}$, $c^h$ and c. Any one rabbit carries two of them. Which term names a gene that exists in more than two forms across a population?

A plant breeder finds that a pink-flowered snapdragon selfed for many generations never yields a line whose seedlings are all pink; red and white plants keep reappearing in every generation. Which pattern of inheritance explains this?

A carnation grower crosses a red-flowered plant with a white-flowered plant. The offspring petals carry sharp red streaks and sharp white streaks on the same petal, with no pink anywhere on the flower. Which pattern of inheritance is this?

In four o'clock plants, flower color is controlled by the alleles $C^R$ and $C^W$. Two pink-flowered plants are crossed. Work out the square. What phenotypic ratio is expected among the seedlings?

A shorthorn bull whose coat mixes red and white hairs is mated with a cow whose coat is entirely red. Use the square. What fraction of the calves is expected to have a coat mixing red and white hairs?

A four o'clock plant that breeds true for red flowers ($C^R{C}^R$) is pollinated by one that breeds true for white flowers ($C^W{C}^W$). Work out the square. What will the seedlings look like?

A man of genotype $I^A$ i has children with a woman of genotype $I^B$ i. Work out the square. Which blood types are expected among their children, and in what ratio?

In the ABO blood group, $I^A$ and $I^B$ are equally expressed and i produces no antigen. Two people of genotype $I^A{I}^B$ have children. Work out the square. What ratio of blood types is expected?

Two people, each of genotype $I^A$ i, have children. Work out the square. What ratio of blood types is expected among the children?

In Andalusian fowl, feather color is controlled by the alleles $F^B$ and $F^W$, and a bird carrying one of each is slate blue. Two slate blue birds are mated and 100 chicks hatch. Use the square. About how many chicks are expected to be slate blue?

A shorthorn cow whose coat mixes red and white hairs is mated with a bull whose coat is entirely white. Work out the square. What phenotypic ratio is expected in the calves?

The human beta-globin gene has the alleles $H^A$ and $H^S$. A person carrying one of each makes normal hemoglobin and sickle hemoglobin. Two such people have children. Use the square. What fraction of the children is expected to make only sickle hemoglobin?

A man of genotype $I^B$ i has children with a woman of genotype i i. Work out the square. What ratio of blood types is expected among their children?

The square sets out a cross between a shorthorn bull that is $C^R{C}^R$ and a cow that is $C^W{C}^W$. Every calf's coat mixes separate red hairs with separate white hairs. Which genotype do those calves carry?

The square sets out a cross between a father of genotype $I^A$ i and a mother of genotype $I^B$ i. One of their children has type O blood, whose red cells carry neither the A antigen nor the B antigen. Which genotype does that child have?

The square sets out a cross between a four o'clock plant with red flowers ($C^R{C}^R$) and one with pink flowers. Some seedlings open red flowers. Which genotype do those red-flowered seedlings carry?

In the MN blood group, the alleles $L^M$ and $L^N$ are equally expressed. The square sets out a cross between a father who is $L^M{L}^N$ and a mother who is $L^M{L}^M$. A child's red cells carry the M antigen and the N antigen. Which genotype does that child have?

In shorthorn cattle, coat color is controlled by the alleles $C^R$ and $C^W$. A calf whose coat is entirely white, with no red hairs anywhere on it, has which genotype?

A hospital laboratory reports that a patient's red blood cells carry the A antigen and the B antigen on their surfaces. Which ABO genotype does this patient have?

In Andalusian fowl, feather color is controlled by the alleles $F^B$ and $F^W$. A bird whose plumage is a uniform slate blue over the whole body has which genotype?

A woman has type A blood. Her mother has type O blood, whose red cells carry no A antigen and no B antigen. Which genotype must the woman have?

A snapdragon nursery records the seedlings from one batch of seed: 48 with red flowers, 95 with pink flowers and 51 with white flowers. Which cross produced this batch?

A cattle herd record shows 31 calves whose coats mix red and white hairs and 29 calves that are entirely white. No calf in the record is entirely red. Which cross produced these calves?

Every calf born to one pair of shorthorn cattle has a coat mixing red and white hairs, and the pair has produced 40 calves with no exceptions. Which genotypes do the two parents have?

A couple's four children have blood types A, B, AB and O. Which pair of genotypes do the parents have?

A poultry breeder mates two Andalusian fowl and records 24 slate blue chicks and 25 black chicks, with no splashed white chick in the hatch. Which cross did the breeder make?

A pink-flowered snapdragon is crossed with a plant whose flower color the gardener did not record. Half the seedlings open pink flowers and half open white flowers. What was the unrecorded plant?

A person inherits one normal beta-globin allele and one sickle allele. Electrophoresis of their blood shows two separate bands, at the positions of normal and of sickle hemoglobin, with nothing between them. Which pattern is this?

A blood sample is tested at a clinic. The red cells clump when anti-A serum is added and they also clump when anti-B serum is added. Which pattern describes the relationship between the $I^A$ and $I^B$ alleles this person carries?

Commercial hatcheries produce slate blue Andalusian chicks by crossing black birds with splashed white birds rather than by mating slate blue birds with each other. Why is the slate blue x slate blue mating a poor choice for a hatchery?

In parts of Africa where malaria is common, the sickle allele $H^S$ remains at a high level in the population. What is the documented advantage held by people who carry one $H^A$ allele and one $H^S$ allele?

In familial hypercholesterolemia, a person with two normal alleles has ordinary blood cholesterol, a person with one faulty allele has roughly twice that level, and a person with two faulty alleles has several times that level. Which pattern is this?

Human red blood cells may carry an M antigen, an N antigen, or one of each, depending on which alleles of the L gene the person has. A person of genotype $L^M{L}^N$ shows the M antigen and the N antigen at full strength. Which pattern is this?