Question

Duroc Jersey pigs are typically red, but a sandy variation is also seen. When two different varieties of true-breeding sandy pigs were crossed to each other, they produced F1 offspring that were red. When these F1 offspring were crossed to each other, they produced red, sandy, and white pigs in a 9:6:1 ratio. Explain this pattern of inheritance in terms of number of genes, and any allele or gene interactions.

Answer 1

Answer:

The sandy variation could be as a result of a homozygous recessive allele at one of two varying genes in these two different types of sandy pigs. Let's refer to them as genes A and B.

A kind of sandy pig may be aaBB and the variety AAbb. The F1 generation in this cross produces heterozygotes for both genes to give all red. This indicates that the A and B alleles are dominant. In the F2 generation, 6 out of 16 give us homozygous for either the aa or bb alleles and produces sandy.

Out of 16 will we have one that would be doubly homozygous and be white. The other 9 will possess at least one dominant allele for both genes.