Leaving Certificate Biology Practice Test

A law is the best fit here. When a statement about how something behaves has been tested repeatedly and consistently over a long time, it’s summarized as a law — a concise description of the observable pattern or relationship under defined conditions. It focuses on what happens and can often be stated mathematically or in general terms. A theory, by contrast, is an explanatory framework that explains why the pattern exists and how it fits with other ideas; even well-supported theories can still be refined. Data and experiments are parts of gathering evidence, not the final descriptive label. So the term describing a theory that has withstood long-term testing is a law.