Question

The red and white colour in horses shows codominance. What would be the result of the cross between a homozygous red horse and a homozygous white horse?
A. The offspring is white.
B. The offspring are red.
C. Offspring has both red and white hairs.
D. The offspring are brown.
E. The offspring is black.

Answer 1

Hint: Codominance and Incomplete dominance are exceptions of Mendel’s law of dominance. In these phenomenons the \[F1\] hybrid does not show phenotypic similarity with any of the parents and a self-cross of \[F1\] hybrid yields a ratio of \[1:2:1\] in \[F2\] generation. These phenomenons are in contrast to the law of dominance where the \[F1\] hybrid shows similarity with the dominant parental phenotype and \[F2\] phenotypic ratio is \[3:1\].

Complete answer:
In the question, the phenomenon of co-dominance has been mentioned so, neither red nor white color of horse would mask the other trait, while both of them would appear simultaneously in \[F1\] hybrid.
Now, look at the options.
Option A: The offspring of the aforementioned cross cannot have white hairs because in codominance the \[F1\] hybrid does not show similarity with any of the parents.
Thus, this option is not correct.
Option B: Again, the offspring can also not have red color of hairs because of the phenomenon of codominance as discussed in the previous option.
Therefore, this option is also not correct.
Option C: This option is correct because in codominance the offspring of the cross between two homozygous parents shows both the traits found in the parents without intermixing. Thus, the horse offspring in this case would have both red and white hairs.
Thus, this option is correct.
Option D: This option is inappropriate as the horse does not have brown color of hairs when the alleles for hair color are codominant.
Thus, this option is incorrect.
Option E: This option is also inappropriate as the horse does not have black color of hairs when the alleles for hair color are codominant.
Thus, this option is incorrect.

Therefore, Option C is the correct answer.

Note:
Codominance is a relation between different variations of a gene. Individuals get hold of one version of a gene, referred to as an allele, from either parent. If the alleles are different, the dominant allele commonly can be expressed, whilst the impact of the opposite allele, referred to as recessive, is masked. However, neither allele is recessive in codominance, and the phenotypes of both alleles expressed.