HESI Biology

HESI Biology Biology is the study of living organisms and to understand anatomy and physiology, a nurse must first grasp the science of biology. While you may not use your knowledge of biology directly every day, biology serves as a prerequisite before moving on to other sciences such as anatomy, physiology, and microbiology. Here are some key concepts you should understand in order to do well on the Biology section of the HESI exam: Classification of Organisms Early biologists faced difficulty in devising a method for discerning living organisms from nonliving things. After developing rules to differentiate life from non­life, scientists then faced the struggle of organizing and classifying life. Taxonomy, or the science of classifying, resulted from these early struggles. Many years of classification have occurred since, and because of advancements in biotechnology, scientists can now categorize life based on similarities and differences at the genetic level. Scientists utilize a hierarchical system for classifying organisms. Six Kingdoms contain the taxonomic breakdown of life. These Kingdoms are further divided into Phyla, then Class, Order, Family, Genus, and Species. A common mnemonic for remembering this hierarchy is, “King Phillip Came Over For Great Spaghetti,” where the first letter of every word indicates the corresponding taxonomic class. Over the years, the taxonomic classification schemes have changed and will continue to change as we further our understanding of genetics. Currently, scientists use Six Kingdoms to subdivide life: Bacteria, Protozoa, Chromista, Plantae, Fungi, and Animalia make up these Six Kingdoms. Scientists categorize organisms within one of these Kingdoms by investigating the organisms’ cellular composition, methods for obtaining and using energy, genotypic similarities, and other techniques. The Scientific Method The Scientific Method is a way of devising and performing experiments that yield meaningful results. It involves a procedural approach to gaining information about the physical world that begins with a formulated question and ends with the rejection of a hypothesis and the reevaluation of the experiment. The Scientific Method can be summarized as the following: