As a result, snapdragon individuals who are homozygous for the functional allele of gene R produce high quantities of the ROS1 transcription factor (functional ROS1 is produced from both copies in the diploid genome of snapdragons), resulting in richly magenta-colored blossoms. In individuals that are heterozygous (with one allele coding for functional, and the other allele for non-functional ROS1 transcription factor) the concentration of functional ROS1 is only half that of the homozygous individual, resulting in lower anthocyanin production and pink blossoms. Finally, in individuals who are homozygous for the allele producing non-functional ROS1, the anthocyanin-synthesis pathway is not activated at all, producing white blossoms.
The phenotypic pattern is a direct result of the amount of functional protein product that was produced, with lower concentrations in heterozygous individuals having an effect on the phenotype. This is called the amount effect, and is commonly responsible for incomplete dominance in phenotypes.
How many phenotypes are maximally possible in single gene traits as described above?
Select all that apply.
a. maximally 2 phenotypes in a single-gene trait with complete dominance
b. maximally 2 phenotypes in a single-gene trait with incomplete dominance
c. maximally 3 phenotypes in a single-gene trait with complete dominance
d. maximally 1 phenotype in a single-gene trait with complete dominance
e. maximally 3 phenotypes in a single-gene trait with incomplete dominance
f. maximally 4 phenotypes in a single-gene trait with incomplete dominance
