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?

Question

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.

Answer 1

The correct answer is C. The theory of evolution explains the development of antibiotic resistance in bacteria through genetic variation. Bacteria have the ability to adapt and evolve over time. Within a population of bacteria, there is genetic variation, meaning that some individuals may possess traits that make them more resistant to antibiotics. When antibiotics are introduced and kill off the susceptible bacteria, the resistant ones are able to survive and reproduce. Over time, the population becomes dominated by the resistant bacteria, making the antibiotic less effective against them. This process is known as natural selection, where organisms with traits that are advantageous in a particular environment have a higher chance of survival and passing on their genes to the next generation.

Answer 2

C. Genetic variation in bacteria made it possible for some individuals to have resistance to the antibiotic, survive, and reproduce.

Answer 3

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.