Ais developed through the scientific method, and it can be modified or improved upon. it may be represented by a model. as seen here, three different models were used to represent atomic structure as ideas changed over time.

I think that the best phrase to fit into the blank is a "scientific theory". 

A scientific theory is developed through experiments which use the scientific method, and a theory can be improved if additional data is available or if people provide suggestions which make the theory fit the data better.  

When our stomach digests the food, the carbohydrates in the food break down into another type of sugar called glucose.