Darwin hypothesized that there are definite steps to natural selection. Consider the model here. Use the Roman numerals (I - III
) to guide you through the steps. Which is an accurate description of Darwin's hypothesized theory of natural selection? A) Sexual reproduction of bacteria cause variation. Some bacteria survive and some do not. Over time all of the bacteria should become extinct. B) In any population, variation exists. Some bacteria are resistant to antibiotics. Most bacteria die, but the bacteria that are resistant survive and reproduce. C) In a population of bacteria that are exposed to antibiotics, some bacteria change their genetic make-up and survive. The new genetic make-up is passed on to offspring. D) There is a change in the environment: an antibiotic is added. Some of the bacteria are capable of changing to the new environment. They survive and reproduce, passing along their favorable traits.
Explanation: Natural selection come into action when some change takes place in the environment which affects the survival of the organism. Here the change is addition of antibiotics. So the bacterial cells which were able to adapt to the change, they survived and rest were killed. These resistant bacterial cells would pass on the genes to next generation and gradually population of resistant bacteria would increase.
Today, drug-resistant infections are a serious threat to people's health. Hundreds of thousands of lives are lost every year because of infections that can no longer be treated with existing drugs. Discovering new antibiotics, able to kill drug-resistant bacteria, is essential to saving modern medicine.
