Download Dihybrid Homework problems

Biologist: ____________________
Period: ________ Date:________
Dihybrid Homework Problems
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1. Genotype Practice – In pea plants purple flowers are dominant to white flowers and axial flowers are dominant to terminal flowers.
purple: _____
white: ______ axial: ______
terminal:_______
Give the genotype for each of the following:
a. Homozygous purple, homozygous axial: _____________
d. Heterozygous purple, homozygous axial: _____________
b. White terminal flowers: _____________
e. Homozygous white, heterozygous axial: _____________
c. Heterozygous purple, heterozygous axial: _____________
f. Heterozygous purple, terminal: _____________
2. 2. Gamete Combination Practice. Give the gamete combination for each genotype.
a. BBDD _____, _____, _____, _____
d. BBDd _____, _____, _____, _____
b. bbdd _____, _____, _____, _____
e.Bbdd _____, _____, _____, _____
c. BbDd _____, _____, _____, _____
f. BbDD _____, _____, _____, _____
3. Corn is bred for traits that improve its usefulness for specific purposes such as taste, sugar content, storage. Corn has a gene for
kernel color and a separate gene for kernel texture. Kernel color alleles are purple (P) and yellow (p). Kernel texture alleles are smooth
(T) and wrinkled (t). Homozygous purple kernel, heterozygous smooth kernel plant is crossed with heterozygous purple kernel,
homozygous smooth kernel plant.
a. Give the genotype cross: ____________x____________
b. List the possible gametes formed by each parent.
_____, ______, _______, _______
_____, ______, _______, _______
c. Complete the punnett square:
d. What would be the genotype ratios of the F1 generation?
e. What would be the phenotype ratio of the F1 generation?
4. As you know by now, inflated pea pods(I) are dominant to constricted pea pods (i) and green pea pods (G) are dominant to yellow
pea pods (g). Predict the probability of offspring from a yellow, constricted pea pod plant with a heterozygous inflated pea pod,
homozygous yellow pea pod plant.
a. Give the genotype cross: ____________x____________
b. List the possible gametes formed by each parent.
_____, ______, _______, _______
_____, ______, _______, _______
c. Complete the punnett square:
d. What would be the genotype ratios of the F1 generation?
e. What would be the phenotype ratio of the F1 generation?
5. In guinea pigs rough coat (R) is dominant over smooth coat (r) and coat pigment or color (P) is dominant to albino or white (p). What
phenotypes would be possible if a heterozygous rough coat, heterozygous color is crossed with heterozygous rough coat albino?
6. In cocker spaniels, black is a dominant trait (B), red is recessive (b). Solid color is dominant (S) and white spotting is recessive (s). A
red male was mated to a black-and-white female. They had five puppies as follows: 1 black, 1 red, 1 black-and-white, and 2 red-andwhite. What are the genotypes of the parents?
7. In humans, polydactyly (P) is a dominant phenotype characterized by having extra fingers and toes. Brachydactyly (B) is a dominant
phenotype characterized by very short terminal bones in the fingers. What is the genotype and phenotype of any unaffected human? If
two humans who exhibit both traits produce a daughter who exhibits polydactyly but normal finger length what can you say about the
parental genotypes?