1. Gas exchange experiment: inspired vs. expired air CO₂ comparison using limewater or hydrogen carbonate indicator, diagram assembly, safety controls, variable standardization. 2. Enzyme inhibition investigation: phosphatase and phenolphthalein substrate, competitive vs. non-competitive inhibitor comparison, colorimeter data plotting, variables control, results interpretation. 3. Blood vessels and circulation: artery vs. vein structure differences, direction of blood flow, additional vessel types, coronary heart disease trend analysis, mortality calculation by population data. 4. Menstrual cycle physiology: birth control methods, uterus lining thickness influenced by oestrogen, menstruation identification, ovulation impact on hormone and lining if fertilization occurs. 5. Lactose intolerance: enzyme deficiency effects, gene silencing, fermentation by gut bacteria, symptoms from osmotic imbalance, evolutionary dietary adaptation explanations. 6. Blood clotting mechanism: platelets, thrombokinase activation, fibrin formation, inheritance of haemophilia (pedigree analysis), probability calculations for offspring genetics.