Sweet yellow tomatoes with a pear shape bring a high price per basket to growers. Pear shape, yellow color, and terminal flower position are recessive traits produced by alleles f, r, and t, respectively. The dominant phenotypes for each trait—full shape, red color, and axial flower position—are the product of dominant alleles F, R, and T. A farmer has two pure-breeding tomato lines. One is full, yellow, terminal and the other is pear, red, axial. Design a breeding experiment that will produce a line of tomato that is pure-breeding for pear shape, yellow color, and axial flower position.

In the fruit fly Drosophila, a rudimentary wing called 'vestigial' and dark body color called 'ebony' are inherited as independently assorting genes and are recessive to their dominant counterparts full wing and gray body color. Dihybrid dominant-phenotype males and females are crossed, and 3200 progeny are produced. How many progeny flies are expected to be found in each phenotypic class?

A variety of pea plant called Blue Persian produces a tall plant with blue seeds. A second variety of pea plant called Spanish Dwarf produces a short plant with white seed. The two varieties are crossed, and the resulting seeds are collected. All of the seeds are white; and when planted, they produce all tall plants. These tall F₁ plants are allowed to self-fertilize. The results for seed color and plant stature in the F₂ generation are as follows:

   F₂ Plant Phenotype    Number

   Blue seed, tall plant.     97

   White seed, tall plant    270

   Blue seed, short plant    33

   White seed, short plant  100

  TOTAL                500

Examine the data in the table by the chi-square test and determine whether they conform to expectations of the hypothesis.

A variety of pea plant called Blue Persian produces a tall plant with blue seeds. A second variety of pea plant called Spanish Dwarf produces a short plant with white seed. The two varieties are crossed, and the resulting seeds are collected. All of the seeds are white; and when planted, they produce all tall plants. These tall F₁ plants are allowed to self-fertilize. The results for seed color and plant stature in the F₂ generation are as follows:

   F₂ Plant Phenotype    Number

   Blue seed, tall plant.     97

   White seed, tall plant    270

   Blue seed, short plant    33

   White seed, short plant  100

  TOTAL                500

State the hypothesis being tested in this experiment.

A variety of pea plant called Blue Persian produces a tall plant with blue seeds. A second variety of pea plant called Spanish Dwarf produces a short plant with white seed. The two varieties are crossed, and the resulting seeds are collected. All of the seeds are white; and when planted, they produce all tall plants. These tall F₁ plants are allowed to self-fertilize. The results for seed color and plant stature in the F₂ generation are as follows:

   F₂ Plant Phenotype    Number

   Blue seed, tall plant.     97

   White seed, tall plant   270

   Blue seed, short plant    33

   White seed, short plant  100

  TOTAL                500

What is the expected distribution of phenotypes in the F₂ generation?

A cross between a spicy variety of Capsicum annum pepper and a sweet (nonspicy) variety produces F₁ progeny plants that all have spicy peppers. The F₁ are crossed, and among the F₂ plants are 56 that produce spicy peppers and 20 that produce sweet peppers. Dr. Ara B. Dopsis, an expert on pepper plants, discovers a gene he designates Pun1 that he believes is responsible for spicy versus sweet flavor of peppers. Dr. Dopsis proposes that a dominant allele P produces spicy peppers and that a recessive mutant allele p results in sweet peppers.

Assuming the proposal is correct, what proportion of the spicy F₂ pepper plants do you expect will be pure-breeding? Explain your answer.

A cross between a spicy variety of Capsicum annum pepper and a sweet (nonspicy) variety produces F₁ progeny plants that all have spicy peppers. The F₁ are crossed, and among the F₂ plants are 56 that produce spicy peppers and 20 that produce sweet peppers. Dr. Ara B. Dopsis, an expert on pepper plants, discovers a gene he designates Pun1 that he believes is responsible for spicy versus sweet flavor of peppers. Dr. Dopsis proposes that a dominant allele P produces spicy peppers and that a recessive mutant allele p results in sweet peppers.

Are the data on the parental cross and the F₁ and F₂ consistent with the proposal made by Dr. Dopsis? Explain why or why not, using P and p to indicate probable genotypes of pepper plants.

A pure-breeding fruit fly with the recessive mutation cut wing, caused by the homozygous cc genotype, is crossed to a pure-breeding fly with normal wings, genotype CC. Their F₁ progeny all have normal wings. F₁ flies are crossed, and the F₂ progeny have a 3:1 ratio of normal wing to cut wing. One male F₂ fly with normal wings is selected at random and mated to an F₂ female with normal wings. Using all possible genotypes of the F₂ flies selected for this cross, list all possible crosses between the two flies involved in this mating, and determine the probability of each possible outcome.