Question

5-Coat colour in cattle is controlled by two codominant alleles. The genotype CRCR results in cattle with a red coloured coat. The genotype CWCW results in cattle with a white coloured coat. The genotype CRCW results in a roan coat; these cattle have a mixture of red hairs and white hairs in their coat. A mating occurs between a red cow and a roan bull. What is the expected ratio of coat colour in the offspring? (1mark)A) 50% red, 50% whiteB) 100% redC) 50% red, 50% roanD) 100% roan

Answer 1

Step-by-step explanation:

In codominance we have the following fact:

If an offspring phenotype is heterozygous, the offspring will exhibit both traits from the parents.

Let us denote by RR the genotype that results in cattle with a red-colored coat and by WW the genotype that results in cattle with a white-colored coat. Then, RW results in a roan coat. Now, if we cross a red cow and a roan bull, we have the following Punnett square:

This means that

1. 50% of the offspring presents the genotype RR (cattle with a red-colored coat)

2. 50% of the offspring presents the genotype RW (roan coat)

for a ratio of 2:2.

We can conclude that the correct answer is:

Answer:

C) 50% red, 50% roan