Listen to a conversation between a student and her biology professor. Student: Professor, I’m confused about the lab report on fruit fly genetics. I thought that all mutations were harmful, but the instructions mention a neutral mutation. Professor: That’s a common misconception. Actually, most mutations are neutral or have no immediate effect on an organism’s fitness. For example, a change in a non-coding region of DNA might not alter protein function at all. Student: So, how do we classify them? Professor: We often look at the phenotype. A harmful mutation reduces survival or reproduction, a beneficial one increases it, and a neutral one doesn’t change fitness. In your experiment, you’ll observe eye color. The white-eye mutation is harmful because it reduces mating success, but the curly-wing mutation is neutral under lab conditions—it doesn’t affect survival. Student: I see. So, do neutral mutations become important over time? Professor: Yes, they can accumulate and provide raw material for future evolution, especially if the environment changes. So, don’t dismiss them as unimportant.
❓ Pregunta What does the professor imply about neutral mutations?
A. They are always harmful because they change DNA.
B. They have no effect on fitness but may be useful for evolution later.
C. They are immediately beneficial and spread quickly.
D. They occur only in non-coding regions and are never expressed.
✅ Respuesta correcta
They have no effect on fitness but may be useful for evolution later.
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