Suppose that two strains of E. coli—strain a (bio- met- leu+ thr+ thi+) and strain b (bio+ met+ leu- thr- thi-)—conjugate. If the two strains are grown on minimal medium, what is the most likely genotype of their offspring?
a. bio+ met- leu- thr- thi+
b. bio+ met+ leu+ thr+ thi+
c. bio+ met+ leu- thr- thi+
d. bio- met- leu- thr- thi+
Answer: b. bio+ met+ leu+ thr+ thi+
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