Final answer:
A mutagen is a physical or chemical agent that permanently changes genetic material, usually DNA, in an organism and increases the frequency of mutations. Mutagens are used in genetic research to induce mutations and study their effects on organisms.
Step-by-step explanation:
A mutagen is a physical or chemical agent that permanently changes genetic material, usually DNA, in an organism and increases the frequency of mutations above the natural background level. Mutagens are used in genetic research to induce mutations and study the effects of these mutations on organisms. They are used to investigate gene function, understand the causes of genetic diseases, study the mechanisms of evolution, and develop new treatments for diseases.