Chapter 2, Problem 18P

In pea plants, the appearance of flowers along the main stem is a dominant phenotype called “axial” and is con-trolled by an allele T. The recessive phenotype, produced by an allelet, has flowers only at the end of the stem and is called “terminal.” Pod form displays a dominant pheno-type, “inflated,” controlled by an allele C, and a recessive “constricted” form, produced by the c allele. A cross is made between a pure-breeding axial, constricted plant and a plant that is pure-breeding terminal, inflated.

(a) The $F_1$ progeny of this cross are allowed to self-fertilize. What is the expected phenotypic distribution among the $F_2$ progeny?

(b) Suppose that all of the $F_2$ progeny with terminal flowers, i.e., plants with terminal flowers and inflated pods and plants with terminal flowers and constricted pods, are saved and allowed to self-fertilize to produce a partial $F_3$ generation. What is the expected phenotypic distribution among these $F_3$ plants?

(c) If an $F_1$ plant from the initial cross described above is crossed with a plant that is terminal, constricted, what is the expected distribution among the resulting progeny?

(d) If the plants with terminal flowers produced by the cross in part (c) are saved and allowed to self-fertilize, what is the expected phenotypic distribution among the progeny?