General Biology: The Principles That Underpin Everything
What you must understand
General biology is the vocabulary layer of the exam: the characteristics of living things (organisation, metabolism, response to stimuli, homeostasis, growth, reproduction, adaptation, evolution), the hierarchy of biological organisation from molecule to biosphere, and the central dogma in outline (DNA → RNA → protein). You should be able to distinguish prokaryotes from eukaryotes, autotrophs from heterotrophs, and to recognise the major macromolecule classes: carbohydrates (energy, structure), lipids (membranes, storage, signalling), proteins (enzymes, structure, transport) and nucleic acids (information). Know the meaning of a catalyst and the basic properties of enzymes: they lower activation energy, are not consumed, are specific, and are sensitive to temperature and pH.
Traps
Questions love near-synonyms. Viruses are not cells and are not usually classed as living by the criteria above; they replicate only inside a host. "Growth" in biology means increase in mass or cell number, not just getting bigger. Enzymes change reaction rate, never the equilibrium constant or the overall energy yield. A common distractor swaps "prokaryote" for "unicellular" - many eukaryotes are unicellular, and all prokaryotes are not bacteria (archaea exist).
Worked rule of thumb
When a question asks which characteristic best separates two groups, choose the one that is definitional rather than incidental. Example: to separate prokaryotes from eukaryotes, the decisive feature is the presence or absence of a membrane-bound nucleus - not size, not the number of cells, not the presence of a cell wall (plants and bacteria both have walls).
Exam habit
Translate each term into one sentence you could say aloud. If you cannot define it in a sentence, you do not yet own it.