Chemistry is the science of elements and compounds made up of atoms, molecules and ions: their structure, properties, behavior and the changes that happen when they react with other substances.
Biology is the science that studies life and living organisms. This includes their physical structure and any chemical processes, molecular interactions, development and evolution.
Physics is the natural science that studies matter, its motion and behavior through space and time, and the related elements of energy and force. Its main goal is to understand how the universe behaves.