instruction:
Given a scientific question and its correct answer, generate supporting facts for the answer. This supporting fact can be an explanation for the answer to the given question.
question:
Question: What causes blue litmus to turn red? Answer: acid
answer:
Acids change the color of certain acid-base indicators. Two common indicators are litmus and phenolphthalein. Blue litmus turns red in the presence of an acid, while phenolphthalein turns colorless.

question:
Question: Viruses were assumed to exist before they were first seen with an electron microscope in which decade? Answer: 1930 ' s
answer:
Viruses were assumed to exist before they were first seen with an electron microscope in the 1930s. Multiple hypotheses for viral origins have been proposed.

question:
Question: Compared to free-floating bacteria, bacteria in biofilms often show increased resistance to what? Answer: antibiotics and detergents
answer:
Compared to free-floating bacteria, bacteria in biofilms often show increased resistance to antibiotics and detergents. Why do you think this might be the case?.