Human Biology and Health
What this domain tests
Human Biology and Health applies physiology to medicine and public health: immunity, endocrine control, circulation, respiration, digestion, pathogens, and noncommunicable disease. Questions often ask you to evaluate evidence about risk and treatment.
Core rules and concepts
- Innate immunity is fast and nonspecific: barriers, phagocytes, inflammation, and complement. Adaptive immunity is specific and slower, using B cells for antibodies and T cells for cell-mediated responses. Memory cells make secondary responses faster and stronger.
- Blood glucose is regulated by insulin, which lowers glucose, and glucagon, which raises it. Diabetes involves inadequate insulin action or secretion.
- Antibiotics target bacterial structures or processes; they do not treat viral infections. Vaccines expose the immune system to antigens without causing the disease.
- Risk factors such as smoking, poor diet, inactivity, and hypertension increase the probability of disease but do not guarantee it.
Worked example
A patient’s antibody titre is 10 before a booster and 160 four weeks later. The fold increase is 160/10 = 16, consistent with a strong secondary immune response. Reasoning: a booster re-exposes memory B and T cells, producing a faster and larger antibody rise than the primary response. A titre measures antibody concentration indirectly, not the number of memory cells.
Traps
Do not say antibiotics kill viruses. Do not confuse the first line of defence with adaptive immunity. Do not interpret a risk factor as a cause in every case. In feedback diagrams, check whether the response increases or decreases the original deviation.