After consulting a genetic map of Drosophila melanogaster, you find that two genes you are interested in lie 72 map units apart. If you do a 2-point testcross for these two genes, what percentage of the progeny do you expect to be recombinant?

The percentage of recombination frequency will be greater than or equal to 50%.

Explanation:

A distance of 72 map units is a substantial distance so two genes located this much distance apart will segregate almost independently or we can say that they will be considered as unlinked genes that is why the recombination frequency will be greater than or equal to 50%. Recombination frequency in turn gives us an idea of how many progeny are produced with genes which underwent crossing over during meiosis in parental gametes so that they have new combinations of genes which are different than parents leading to variations. In short in this example, 50% or more progeny will be recombinants.

try using substitution:

x + y - 6 = x - y. (i'm not giving you the exact answer). since 0 = x - y, then sub 0 in the equation with x - y. combine your like terms, and then use inverse operations, and you'll have your answer.

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