Dwarf parent: t Possible gametes: Tt 100% t Dwarf Tt 50% of F,'s are tall Test parent: Tt Possible gametes: tt 50% T 50% t Test parent: TT Possible gametes: 100% T t 100% of F,'s 50% of F,'s are tall are dwarf FIGURE 16-14 Test crosses to determine whether a plant with the dominant phenotype is heterozygous or homozygous. Of the data in this diagram, you would not know the genotypes of the test parents before the test cross; those data are what you are trying to discover. If you want to find only a single homozygote or heterozygote, you would need to do test crosses on only one or a few plants. Imagine, however, that you had done an experimental cross for a trait that you assumed would give you a 3:1 ratio; it would be necessary to do test crosses on a large number of progeny plants with the dominant phenotype just to confirm your experiment.

In snapdragons, red flower color is incompletely dominant to white flower color. Tall is completely dominant to short. You cross a true breeding red-flowered tall plant to a true breeding white-flowered short plant. You cross the F1 offspring to each other. In the F2, what is the probability of offspring that are white-flowered and tall?

Which of the following is NOT required for adaptations to evolve? Heritable variation in fitness Genetic diversity within populations Sexual reproduction Natural selection Question 2

Gregor Mendel discovered the basis of heredity with his sweet pea plant experiments. In his studies, he determined that certain traits, such as pod color and pea shape, express complete dominance. Trait Dominant Recessive Pod color Yellow Green Pea shape Round Wrinkled A cross occurs between a plant with heterozygous yellow pods and wrinkled peas and a plant with green pods and heterozygous round peas. What is the probability that the offspring will exhibit recessive genes for both traits? a) 1/2 b) 1/4 c) 1/8 d) 1/16

In swallowtail butterflies, let's pretend that the R gene codes for coloring on the forewing. The R1 allele, which codes for red color, is dominant to the R2 allele, which codes for white color. If R1 is a recessive lethal allele, what phenotypic ratio would you expect when crossing two swallowtails with red forewings?  1 red : 2 white  1 red : 3 white  3 red : 1 white  there is not enough information given to answer this question  1 red : 1 white  2 red : 1 white

In a particular plant, leaf color and leaf shape are controlled by two linked genes. Leaves of the wild-type plant are red. A recessive mutation in this gene causes white leaves. Wild-type leaves are pointed and a recessive mutation in this gene causes them to be smooth. The following cross was performed: Heterozygous red, pointed 43 white, smooth 42 red, pointed 8 white, pointed 7 red, smooth Homozygous white, smooth RESULTS: What is the recombination frequency between the gene for leaf color and the gene for leaf shape?