Some regions of the plasma membrane, called lipid rafts, have a higher concentration of cholesterol molecules. at higher temperatures, these regions

Many organs are involved in the processes of keeping the blood and the body clean. when poisonous or harmful substances are in the blood, they are absorbed by the and released in a less harmful form. when wastes are present in the blood, they are filtered out and removed from the body by the

During the day, plants produce by splitting water molecules in the light-dependent reactions of photosynthesis. at the same time, plants use cellular respiration to produce some of the needed by the light-independent reactions to make sugars. during the night, plants produce because takes place.

Which of the following requires the use of energy and the of transport proteins to move a molecule across a cell membrane?