16. If the nucleotide sequence of a section of DNA that codes for a protein is changed, which of the following has occurred?
Answer: C
A mutation has occurred.
A change in the nucleotide sequence of DNA that codes for a protein indicates that a mutation has occurred. Mutations can result from various factors and are critical in the process of evolution and genetic variation.
A) Transcription
Transcription is the process by which the DNA sequence is copied into RNA, but it does not involve a change in the nucleotide sequence of the DNA itself. Therefore, this option is incorrect as it describes a different biological process.
B) A new adaptation
While adaptations can arise from mutations, a new adaptation specifically refers to traits that enhance survival or reproduction in a particular environment. Simply changing a nucleotide sequence does not automatically imply the development of a new adaptation; thus, this option is not correct in this context.
C) A mutation
This option correctly identifies the scenario where the nucleotide sequence of DNA has been altered. Mutations are defined as changes in the genetic material, and this is exactly what the question describes.
D) Natural selection
Natural selection is a process that occurs after mutations create variations within a population. It involves the differential survival and reproduction of individuals based on those variations. Since the question specifically addresses a change in the nucleotide sequence, not the subsequent effects on the population, this option is incorrect.
Conclusion
The correct answer, "a mutation," clearly explains the alteration of the nucleotide sequence in DNA that codes for a protein. Options A, B, and D describe processes or concepts that do not directly relate to a change in the DNA sequence itself, reinforcing that C is the only appropriate choice.