Problem:

In Drosophila there is a dominant allele for gray body color and a dominant allele of another gene for normal wings. The recessive alleles of these two genes result in black body color and vestigial wings, respectively. Flies homozygous for gray body and normal wings were crossed with flies that had black bodies and vestigial wings. The F1 progeny were then crossed with homozygous recessives, with the following results: 492 flies with gray body and normal wings; 445 with black body and vestigial wings; 18 with gray body and vestigial wings; and 30 with black body and normal wings.

Required:

Question 1: Are these two genes linked or independently inherited? Support your answer with data.

Question 2: If these two genes are linked, how many units apart are they on the chromosome?

Could someone help to explain the answer of these questions.