Scientific models can be used for a variety of different purposes. which of the following statements about scientific models is not true?
a. scientific models can save money and lives.
b. scientific models allow scientists to test their predictions.
c. scientific models allow scientists to study systems that no longer exist.
d. scientific models are used rarely

Consider a culture medium on which only gram-positive organisms such as staphylococcus aureus colonies can grow due to an elevated nacl level. a yellow halo surrounds the growth, indicating the bacterium fermented a sugar in the medium, decreasing the ph as a result and changing the color of a ph indicator chemical. this type of medium would be referred to as a differential and enrichment culture.