In the respiration equation does energy act as a reactant or a product

How are mutations continually being generated in a population (what are some of the causes of mutatuions? ) explain

The chemical form of energy that is useable by the cell to do work

Which of these has happened to your food by the time it reaches your small intestine? a. all the macromolecules have been broken down completely. b. lipids and starches have been partially broken down. c. starches and proteins have been partially broken down. d. proteins and lipids have been broken down into subunits.