Name: ________________________________________________ Hour: _____ Number: _____
Dihybrid Crosses Using the Fork-line Method
1. Gregor Mendel researched pea plants and discovered the following. Round peas
(allele is R) and Tall plants (allele is T) traits are both dominant to wrinkled peas and
short plants. If a pea plant is both heterozygous for round peas and heterozygous for
tall plant is crossed with a pea plant has wrinkled peas and is a short plant, what would
be the probabilities for each possible offspring phenotype?
Cross: __________ X __________ Gametes: ___ ___ ___ ___
Fork-line:
___ ___ ___ ___
Probability:
2. If a two pea plants where crossed that are both heterozygous for both genes (a true
dihydrid). What is the probability of getting a pea plant with wrinkled peas and being a
tall plant?
Cross: __________ X __________ Gametes: ___ ___ ___ ___
Fork-line:
Probability:
___ ___ ___ ___
Name: ________________________________________________ Hour: _____ Number: _____
3. In tomatoes, red color is dominant over yellow color, and juiceless tomatoes are
dominant over juicy tomatoes. Cross a tomato plant that is hybrid (heterozygous) for
both traits with a plant that does not show either dominant phenotype. What is the
chance of getting a tomato that is yellow and juiceless? _________________
Cross: __________ X __________ Gametes: ___ ___ ___ ___
Fork-line:
___ ___ ___ ___
Probability:
4. Using the information from problem #3, cross a tomato plant that is homozygous red
and is juicy with a plant that is yellow and is heterozygous for juicelessness. What is
the chance of getting a plant that shows both dominant traits? ___________________
Cross: __________ X __________ Gametes: ___ ___ ___ ___
Fork-line:
___ ___ ___ ___
Probability:
5. Explain why Heinz Tomato Company would be interested in the genetics of tomatoes.