Consider the following experiment. First, large populations of two mutant strains of Escherichia coli are mixed, each requiring a different, single amino acid. After plating them onto a minimal medium, 45 colonies grew. Which of the following may explain this result?
A) The colonies may be due to back mutation (reversion).
B) The colonies may be due to recombination.
C) Either A or B is possible.
D) Neither A nor B is possible.

Question

Quizplus · Accepted Answer

Since each mutant requires a different, single amino acid, it is unlikely that they could have acquired the necessary mutations for growth on the minimal medium through recombination. Back mutation (reversion) could be a possible explanation, but it is also possible that recombination occurred. Therefore, either A or B is a possible explanation for the growth of the colonies.

Consider the Following Experiment