Question

Inheritance of roan coat in cattle is an example of

• A. incomplete dominance
• B. codominance
• C. multiple allelism
• D. none of these

Answer 1

Answer: (B)

Coat colour in short-horned cattle is an exampl of co-dominance. If a cattle with black coat is crossed with a cattle with white coat, the $F_1$ hybrids possess neither black nor white coat colour, but have roan coat colour, where black and white patches appear separately. The effect is produced due to juxtaposition of small patches of red and white colour. Hence the alleles which are able to express themselves independently when present together are called codominant alleles and the inheritance pattern is called co-dominance. On inbreeding, the roan hybrids produce three types of cattle $—$ red, roan and white in the ratio of $1:2:1$.