Mutation Rates Are Similar in Bacteria and Archaea, Yet Certain

Multiple Choice

Mutation rates are similar in Bacteria and Archaea, yet certain stressful conditions mutation rates increase. Why is the mutation rate not constant and close to zero all of the time?

A) Increased mutation rates can be advantageous in rapidly changing environments because some random mutations may be useful for survival.
B) Microorganisms carefully control the mutation rate of their DNA to match the environmental conditions and maximize evolution.
C) The increased mutation rate under stressful conditions is an indication that the microorganisms can no longer replicate their DNA properly and are about to die.
D) Constant mutation rates would halt evolution completely.