Final answer:
Germline mutations can be passed on to offspring, while somatic mutations cannot. Mutagens are physical or chemical agents that can cause DNA changes.
Step-by-step explanation:
Germline mutations occur in gametes, such as eggs and sperm, and can be passed on to offspring. Every cell in the offspring will have the mutation if it is present in a germ cell. On the other hand, somatic mutations occur in other cells of the body and cannot be passed on to offspring.
A mutagen is a physical or chemical agent that can cause a permanent change in an organism's DNA. Mutagens include things like exposure to radioactivity, UV light, certain chemicals, and viruses. Sometimes, mutations may be harmful, beneficial, or have no effect.