Question

The horse breeding program works with roan coat color, where red and white hairs appear together in heterozygous horses (RR = red, WW = white, RW = roan). This inheritance pattern differs from simple dominance. What type of inheritance does roan coat color demonstrate?
Question 9 options:

Environmental inheritance, where coat color depends on nutrition and climate

Codominance, where both alleles are expressed simultaneously in heterozygous individuals

Recessive inheritance, where the roan phenotype only appears in homozygous individuals

Complete dominance, where one allele completely masks the other allele's expression

Answer 1

Codominance — both alleles are expressed simultaneously in heterozygotes, producing the roan phenotype (RW shows both red and white hairs), whereas RR = red and WW = white.