Basic Sciences Foundations
What the exam expects
Basic sciences underpin every bench decision, so questions here test whether you can connect chemistry, biology, and physics to laboratory practice rather than recite isolated facts. Expect coverage of acid-base and buffer chemistry, the behavior of solutions and colligative properties, spectrophotometry and the Beer-Lambert relationship, enzyme kinetics, and the structure and function of macromolecules (proteins, nucleic acids, carbohydrates, lipids). Cell biology basics - membrane transport, organelles, and the cell cycle - also appear because they explain phenomena such as hemolysis, osmotic fragility, and why certain analytes are intracellular.
Concepts to master
Know the Henderson-Hasselbalch relationship and how buffers resist pH change near their pKa. Understand molarity, normality, and how to prepare dilutions and serial dilutions. Be able to interpret a standard curve and explain why absorbance is proportional to concentration only within the linear range. For enzymes, understand Km and Vmax qualitatively and the difference between competitive and noncompetitive inhibition. For nucleic acids, know base pairing, the directionality of synthesis, and the principle behind hybridization.
Traps
Common distractors include confusing molarity with osmolality, assuming absorbance remains linear at high concentration, and misidentifying which buffer component changes in a Henderson-Hasselbalch calculation. Watch for questions that ask for the effect of dilution on a measured concentration versus on total amount of analyte.
Worked rule of thumb
For a dilution series, use C1V1 = C2V2. To make 100 mL of a 0.5 mol/L solution from a 2.0 mol/L stock: V1 = (0.5 × 100)/2.0 = 25 mL of stock diluted to 100 mL. Always check units and confirm the final volume, not the volume of diluent added.