Which statement best describes the principle of complementarity of structure and function?

• A. Function is independent of structure
• B. Structure determines function
• C. There is no relationship between structure and function
• D. Both structure and function are irrelevant to each other

Answer: (B)

The main idea is that form enables function. The way something is built—the shape, tissues, and arrangement—directly determines what it can do. For example, bones are rigid and strong to support the body and protect organs; the heart’s muscular walls and valves are arranged to pump blood efficiently in one direction; neurons have long, branched extensions that maximize signal transmission and processing; enzymes have precise active-site shapes that fit particular substrates to speed reactions. Because structure sets the possibilities for function, the best statement is that structure determines function. If the structure were different, the function would change accordingly. Saying there’s no relationship or that function is independent ignores the clear links we see between anatomy and physiology.