initially, biology is a lot of memorization, which is mainly caused by the immense amount of vocabulary that has to be learned in a short amount of time. this of course depends upon the section of biology that you are learning (cell (eukaryotic/prokaryotic), anatomy, ecology, physiology, organismal, etc.) and this vocabulary can vary slightly between disciplines. the concepts, however, are not at all memorization and require a keen mind.
depending upon where you are at in your education, the first objective should be to learn the basic vocabulary (organelles, where they're located intracellularly, a basic function of each, etc.) of the field. this can be done by flashcards. once you have this down, the concepts should come a little easier and learned in a manner that you are comfortable with.
as you progress in biology, memorization plays no part and conceptual methods are just as essential as they are in fields like physics or math.
