Mendelian Genetics

True breeding tall peas are crossed with true breeding dwarf peas. The resulting progeny are all tall. This outcome tells you that:

  tall       dwarf    is dominant to   tall       dwarf  

and that you should use the symbols   T/t       D/d    for the logic.

P phenotype: Tall
genotype: DD
x phenotype: Dwarf
genotype: dd
F1 are all: phenotype: Tall
genotype: Dd


F1 x F1
F2 D d
D phenotype: Tall
genotype: DD
phenotype: Tall
genotype: Dd
d phenotype: Tall
genotype: Dd
phenotype: Dwarf
genotype: dd


The two possible test-crosses:
F2 phenotype: Tall
genotype: DD
x phenotype: Dwarf
genotype: dd

phenotype: Tall
genotype: Dd
phenotype: Tall
genotype: Dd
phenotype: Tall
genotype: Dd
phenotype: Tall
genotype: Dd

and/or

F2 phenotype: Tall
genotype: Dd
x phenotype: Dwarf
genotype: dd

phenotype: Tall
genotype: Dd
phenotype: Tall
genotype: Dd
phenotype: Dwarf
genotype: dd
phenotype: Dwarf
genotype: dd

This page © Ross E. Koning 1994.

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