Unit 2: Maintaining the internal environment
8 dot points across 2 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.
Topic 1: Homeostasis
- Describe endocrine control of the internal environment, including the role of hormones, target cells, the hypothalamus and pituitary gland, and the regulation of blood glucose by insulin and glucagon
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.
9 min answer → - Explain the concept of homeostasis and the role of negative feedback in maintaining a stable internal environment, including stimulus, receptor, control centre, effector and response
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.
8 min answer → - Describe nervous control, including the structure of a neuron, the generation of action potentials, synaptic transmission and the reflex arc
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.
9 min answer → - Describe osmoregulation and excretion in mammals, including the structure and function of the nephron and the role of ADH in regulating water balance
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.
9 min answer → - Explain thermoregulation in endotherms and ectotherms, including behavioural and physiological responses to heat and cold
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.
8 min answer →
Topic 2: Infectious disease and the immune response
- Describe the first, second and third lines of defence in vertebrates, including innate immune responses (barriers, inflammation, phagocytes) and adaptive immune responses (humoral immunity through B cells and antibodies, cell-mediated immunity through T cells)
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.
10 min answer → - Describe the main groups of pathogens (bacteria, viruses, fungi, protists, prions) and their modes of transmission, distinguishing between communicable and non-communicable disease
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.
8 min answer → - Explain how vaccines work, the role of herd immunity, and the development and implications of antibiotic resistance for human health
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.
9 min answer →