Humans and other complex organisms have a hierarchical system of organization. which of the following statements is true regarding this system of organization?
a. atoms are made up of cells
b. organs are made up of organ systems
c. cells are made of tissues
d. organs are made of tissues

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.