The graph shows how many beetles in one population fall into each wing-length range. What does the shape of this distribution suggest about how wing length is inherited?

Every student in a school was tested for the ability to taste the chemical PTC, and the graph shows the result. Which conclusion about this trait does the graph best support?

A student claims that kernel weight in this population of maize is controlled by one gene with two alleles. Which feature of the graph argues against that claim?

A trait shows a smooth, bell-shaped distribution across a large human population, with most people near the middle and few at either extreme. Which trait fits that pattern?

In a herd of Shorthorn cattle, every animal is either red, white, or roan, a mix of red and white hairs. No other shades appear, and roan calves come from a red parent crossed with a white parent. What explains this?

A trait is controlled by two genes. Each gene has one allele that adds to the trait and one that does not, and the phenotype depends only on how many adding alleles an individual carries. How many phenotype classes are possible?

Grain color in one wheat variety depends on four genes, each with one color-adding allele and one non-adding allele, and the shade depends only on the number of color-adding alleles present. How many shades are possible?

The bars show every shade of kernel color found in a large maize population, from palest on the left to darkest on the right. If each contributing gene carries one color-adding allele, how many genes best fit the number of shades shown?

The graph shows every phenotype class for seed color in one plant population, palest class on the left. Which statement about the trait does the graph best support?

A polygenic trait is modeled with genes that each carry one contributing allele. If one more such gene is added to the model, what happens to the number of phenotype classes?

Identical twin sisters were raised apart from birth, one where food was plentiful and one where it was often scarce. As adults their body masses differ by 15 kilograms. What best accounts for that difference?

A Himalayan rabbit has white body fur but black fur on its ears, nose, feet and tail. When a patch of white body fur is shaved and an ice pack is held on the bare skin, the fur that grows back there is black. What does this show?

All the plants in this experiment are cuttings taken from one parent plant, and each group was grown under a different light level. The graph shows the mean height reached by each group. What does the result show?

The graph shows the mean adult height of men in one country measured in three different years. Public health records show the population's gene pool changed very little over that period. What best explains the trend?

A field is planted with corn from a single inbred line, so the plants are almost genetically uniform. At harvest the plants still range from short to tall across the field. Why?

Two groups of genetically identical mice were raised apart. The group fed a high-calorie diet averaged 40 grams as adults; the standard-diet group averaged 28 grams. How much of the 12-gram difference between the group means is due to genetics?

In a three-gene additive model of skin color, each dark-pigment allele adds the same melanin and the shade depends only on their number. Two AaBbCc parents have children. As a number of dark-pigment alleles, what is the lightest shade a child can have?

In the same three-gene additive model, the capital letter of each gene is the pigment-adding allele. How many pigment-adding alleles does an individual of genotype AaBBCc carry?

Seed weight in one plant is set by two genes, and each capital-letter allele adds the same weight. A plant of genotype AaBb is crossed with one of genotype aabb. As a number of weight-adding alleles, what is the heaviest seed the cross can give?

In a three-gene additive model of skin color, shade depends only on the number of capital-letter pigment alleles. Which genotype gives the same shade as AaBbCc?