Final answer:
Mutation is the basic source for biological change. It refers to a change in the sequence of bases in DNA or RNA, and it contributes to the diversity of species.
Step-by-step explanation:
The basic source for biological change is mutation. Mutation refers to a change in the sequence of bases in DNA or RNA, and it is responsible for introducing new genetic characteristics in organisms. While most mutations have no effect or may be harmful, some mutations are beneficial and contribute to the diversity of species.
Mutations can occur naturally, but their frequency can also be increased by physical and chemical agents like ultraviolet light and radiation. Overall, mutation is an essential process for evolution to occur and is considered the ultimate source of new genetic material.