What happens to a glass of water at a temperature of 20°c when it is placed into a freezer set at –10°c? a; it cools to –10°c, where it stays until freezing is complete. b; it freezes, then the temperature drops to 0°c and then to –10°c. c; it cools to 0°c, where it stays until freezing is complete. d; it freezes, then the temperature drops to 0°c and stays there.

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.