This is a complex question, but essentially, what this means is that how things are made up affects how they work. Just like how a a machine cannot run without its gears being placed next to each other, biological systems cannot function properly if they do not have the physical structures that allow for optimal functioning in a specific environment. For example, the cell membrane (in animal, Eukaryotic cells) is made up of a phospholipid bilayer as well as a number of glycoproteins, cholesterol, and more. One of the main imperatives for homeostasis (balance within a biological system such as the human body) is to maintain some level of fluidity in this bilayer. That is, one main function of the bilayer is to be fluid. In colder temperatures, it is harder for the bilayer to move-- almost like it freezes up. Cells can compensate by decreasing the length of phospholipid tails. This basically makes the bilayer thinner, and more easily bendable. Like the difference between cardstock paper and origami paper, the thinner the layer, the easier it it to bend which increases fluidity in cells. By altering the structure of the phospholipids, it is harder for the membrane to "freeze" into a solid. This is an example of how a cells altered structure affects its function.
