Using the information from problem 4, scientists do a further testcross using a heterozygote for height and nose morphol- ogy. the offspring are tall-upturned snout, 40; dwarf-upturned snout, 9; dwarf-downturned snout, 42; tall-downturned snout, 9. calculate the recombination frequency from these data, and then use your answer from problem 4 to determine the correct order of the three linked genes.