Unit 2: Maintaining the internal environment

A focused answer to the QCE Biology Unit 2 dot point on endocrine control. Defines hormones, distinguishes steroid and peptide signalling at target cells, lays out the hypothalamic-pituitary axis and traces blood glucose regulation by insulin and glucagon as a negative feedback loop.

A focused answer to the QCE Biology Unit 2 dot point on homeostasis. Defines homeostasis around a set point, lays out the stimulus to receptor to control centre to effector to response pathway, contrasts negative and positive feedback and uses thermoregulation and blood glucose as worked examples.

A focused answer to the QCE Biology Unit 2 dot point on nervous control. Describes the structure of a neuron (dendrites, soma, axon, myelin sheath), the three phases of an action potential, chemical synaptic transmission and the five components of a reflex arc.

A focused answer to the QCE Biology Unit 2 dot point on osmoregulation. Walks through the four processes of the nephron (filtration, reabsorption, secretion, excretion), names each region (glomerulus, PCT, loop of Henle, DCT, collecting duct) and explains the role of ADH in adjusting urine concentration through negative feedback.

A focused answer to the QCE Biology Unit 2 dot point on thermoregulation. Contrasts endotherms and ectotherms, lists behavioural and physiological responses to heat (sweating, vasodilation) and cold (shivering, vasoconstriction), and connects each to negative feedback through the hypothalamus.

A focused answer to the QCE Biology Unit 2 dot point on the immune response. Names the first, second and third lines of defence, walks through the inflammatory response and phagocytosis (innate), then contrasts humoral immunity (B cells, antibodies) and cell-mediated immunity (T cells) including immunological memory.

A focused answer to the QCE Biology Unit 2 dot point on pathogens. Names the five pathogen groups (bacteria, viruses, fungi, protists, prions) with a named human disease for each, lists the main modes of transmission (direct contact, droplet, airborne, vector, waterborne, foodborne, blood-borne) and distinguishes communicable from non-communicable disease.

A focused answer to the QCE Biology Unit 2 dot point on vaccines and antibiotic resistance. Explains how vaccines trigger a primary response to leave memory cells, defines herd immunity and the thresholds that protect communities, and walks through how antibiotic resistance evolves and what it means for public health.