Final answer:
Cholesterol is the component that buffers temperature effects on cell membranes, maintaining fluidity and ensuring proper function across a range of temperatures.
Step-by-step explanation:
The component that helps membranes resist changes in fluidity is cholesterol. It functions alongside phospholipids in the membrane to buffer the effects of temperature changes. At lower temperatures, cholesterol prevents the membrane from becoming too rigid. Conversely, at higher temperatures, it prevents the membrane from becoming too fluid. This ability to maintain membrane fluidity across various temperatures ensures that the membrane remains functional, capable of permitting necessary substances to pass through while keeping others out.
Cholesterol's role is crucial because the fluidity of the membrane affects its basic functions, such as transporting materials in and out of the cell. It also helps in organizing transmembrane proteins into lipid rafts, which are important for the signalling and sorting processes within cells.