From looking at the past papers about 90% of the marks for Biology can be gained from knowledge of all the definitions and theory. Most questions are not direct definitions but theory questions like "describe the..." and "draw the...". Direct definitions are about 20% of the paper. As the paper is mostly theory based, calculations are quite rare unlike chemistry and physics.
For chemistry on the other hand the marks are more mixed up. I would say about 55 - 60% can be gained from definitions and theory while the rest come from calculations. The first few lab experiment and... (More)