What is well-tested explanation that brings together many observations in science would include such things as evolution, plate tectonics and biogenesis?

The correct answer is a theory.

A theory is a rational and contemplative kind of generalizing or abstract thinking or the outcomes of such thinking. On the basis of the context, the outcomes might involve generalized illustrations of how nature functions.

A theory can be a source of knowledge that may or may not is related to the specific explanatory models. To theorize is to create the body of knowledge.