Final answer:
The hypothesis of "directed mutation" suggests that mutations can be purposeful, induced by organisms in response to environmental changes or stress factors. Experimental evidence supporting this idea includes studies showing increased mutation rates in specific genes under stress conditions. However, experimental evidence refuting this hypothesis comes from research showing that mutations are generally random and occur spontaneously without any organism-driven control.
Step-by-step explanation:
The hypothesis of "directed mutation" suggests that mutations in DNA can be directed or purposeful, rather than random. This hypothesis proposes that organisms have mechanisms to induce specific mutations that are beneficial for their survival in response to environmental changes or stress factors. The experimental evidence supporting this idea includes studies that have shown certain organisms can increase the mutation rate in specific genes under stress conditions. For example, bacteria have been found to increase the mutation rate in antibiotic resistance genes when exposed to antibiotics.
On the other hand, experimental evidence refuting the idea of directed mutation comes from studies that show mutations are generally random and occur spontaneously without any organism-driven control. For instance, research on the distribution of mutations in DNA sequences has shown that mutations are not biased towards specific genes or regions, suggesting they are not directed by the organism.