In Maize,two Plants That Are Both Heterozygous for the Recessive

Multiple Choice

In maize,two plants that are both heterozygous for the recessive alleles a and b are crossed.What frequency of double-mutant progeny will appear if a and b are 7.2 map units apart,and both parents carry a and b in repulsion (trans) ?

A) 0.001296
B) 0.005184
C) 0.036
D) 0.0625
E) 0.072