Humans developed antibiotics to fight bacterial infections. However, some antibiotics are no longer effective in killing the bacteria they once killed. How does the theory of evolution explain this?
A.
The antibiotic mutated the bacteria, which allowed resistance to develop.
B.
After being exposed to the antibiotic, individual bacteria acquired the ability to resist the antibiotic.
C.
Genetic variation in bacteria made it possible for some individuals to have resistance to the antibiotic, survive, and reproduce.
D. The antibiotic mutated to an ineffective form.
1 answer
C is the common reason. The few cells that have resistance, or have a mutation which causes resistance, reproduce. Any genetic variation which favors survivability, or increases reproduction rate, becomes dominate.
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