Final answer:
Cell membranes change state by undergoing a phase transition, adjusting from more solid to more fluid and vice versa in response to temperature changes, not through polymerization, condensation, or denaturation.
Step-by-step explanation:
In response to temperature changes, cell membranes change state to become more solid or more fluid by undergoing a phase transition. This is not a polymerization, condensation, or denaturation process. Instead, the cell membrane adjusts its fluidity in response to temperature to maintain proper function. In cold environments, for example, membranes can become less fluid and more likely to rupture. Organisms may adapt by including more unsaturated fatty acids in their cell membranes, which prevent the membrane from becoming too solid.
Phase changes occur when a substance changes from one state of matter to another, involving the rearrangement of molecules and often resulting from a temperature change. Freezing (liquid to solid) and vaporization (liquid to gas, including boiling and evaporation) are examples of phase changes to less and more energetic states, respectively. Sublimation is the phase change from solid to gas.