Complete the following paragraph to summarize the methods by which cells move material without expending energy.
a. In ____ transport, materials move down a concentration gradient, meaning materials move from areas of ____ concentration of particles to areas of ____ concentration of particles. This process ____ require energy.
b. There are three types of passive transport. ____ describes the physical process in which small molecules are not rejected by the membrane and readily cross the cell membrane.
c. In situations in which the hydrophobic and hydrophilic regions of the membrane prevent molecules from diffusing across the membrane, a ____ serves as carrier or channel for the materials to pass. This process is called ____
d. Determined by the concentration of ____ in solution, if the solutes across the membrane are unequal, water will move across a membrane from an area of high concentration to an area of low concentration. This process is called ____