Transport protein that provides a tube-like opening in the plasma membrane through which particles can diffuse is used during active transport but not passive transport process by which a cell takes in material by forming a vacuole around it

stratosphere: as the altitude increases, the air temperature increases. the stratosphere has a layer of ozone, called the ozone layer. this layer absorbs most of the ultraviolet radiation from sunlight. this results in the stratosphere being warmer.