You carry out a trihybrid cross (a cross in which the parental plants differ for three characters)  between a tall pea plant with round, yellow seeds (TT RR YY) and a short pea plant with wrinkled, green seeds (tt rr yy).  The parental plants are homozygous for all of the three characters. They are crossed to produce the F1 generation. Tall, round, and yellow are the dominant traits for each character. What will be the phenotypes of the F1 generation?

In a certain type of pea plant, the gene for yellow color (Y) is dominant to the gene for green color (y), and the gene for round shape (R) is dominant to the gene for wrinkled shape (r). If a homozygous dominant plant is mated with a homozygous recessive plant (P-gen), what proportion in the F2 generation will be homozygous recessive? a) 1/4 b) 1/16 c) 3/4 d) 3/8

In Drosophila, white eyes (w) are recessive to red eyes (w+) at one locus and black body (b) is recessive to gray body (b+). A homozygous white eyes, gray bodied female is crossed with a homozygous red eyes, black bodied male to produce the F1 progeny. The F1 progeny are testcrossed and produce the following progeny: White eyes, black body: 212 White eyes, gray body: 288 Red eyes, black body: 308 Red eyes, gray body: 192 Does the evidence indicate that w and b loci are linked? Explain why or why not? If they are linked, what is the map distance between the two loci? If they are not linked, what is the map distance between the two loci? If they are linked, are the allels in the F1 in coupling or repulsion? How do you know? Draw the genotypes of all individuals described in the problem (original parents, F1, testcross, and F2 progeny) using the appropriate notation.

The phenotype of crooked wings (cw) in Drosophila melanogaster is caused by a recessive mutant gene that independently assorts with a recessive mutant gene for hairy (h) body. Assume that a cross is made between a fly with normal wings and a hairy body and a fly with crooked wings and normal body hair. All F1 flies from this cross were wild-type, and these flies were crossed among each other to produce 288 F2 offspring. Which phenotypes would you expect among the offspring in the F2 generation, and how many of each phenotype would you expect?