Question

Flower color in a particular plant species is determined by one gene locus. The allele at the locus can code for either red flowers or blue flowers. When two such plants are crossed, however, some of the offspring produce purple flowers. What is the genotype of the plants with purple flowers?
A.
an allele for red flowers on both homologous chromosomes
B.
two alleles for red flowers on one homologous chromosome, and two alleles for blue flowers on the other
C.
an allele for purple flowers on both homologous chromosomes
D.
an allele for red flowers on one homologous chromosome, and an allele for blue flowers on the other

Answer 1

The answer is D. This is an exmaple of incomplete dominance. Red and blue make purple. Because there is no purple alleles, C is false. Because there you can only have 2 alleles total B is false. A is false because having two red alleles makes a red flower.