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EnglandBiology

Module 5: Communication, homeostasis and energy

6 dot points across 6 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How does negative feedback keep the internal environment stable, and how do the kidneys filter blood and control its water potential?

5.1.2 Homeostasis and excretion: the principles of homeostasis and negative feedback; the role of the liver in deamination and detoxification; the structure of the nephron and the processes of ultrafiltration and selective reabsorption; and osmoregulation by ADH acting on the collecting duct.
A focused answer to the OCR H420 5.1.2 dot point on homeostasis and the kidney. Covers negative feedback, the liver's role in deamination and detoxification, the nephron, ultrafiltration and selective reabsorption, and osmoregulation by ADH acting on the collecting duct.
14 min answer →

How do hormones coordinate the body, and how is blood glucose concentration controlled by insulin and glucagon?

5.1.4 Hormonal communication: the principles of hormonal coordination and the contrast with nervous coordination; the structure and function of the adrenal glands and pancreas; the control of blood glucose concentration by insulin and glucagon (glycogenesis, glycogenolysis and gluconeogenesis); the second messenger model of adrenaline and glucagon; and the causes of type 1 and type 2 diabetes.
A focused answer to the OCR H420 5.1.4 dot point on hormonal communication. Covers hormonal versus nervous coordination, the adrenal glands and pancreas, the control of blood glucose by insulin and glucagon, the second messenger model, and the causes of type 1 and type 2 diabetes.
14 min answer →

How is a nerve impulse generated and propagated, and how is it transmitted across a synapse?

5.1.3 Neuronal communication: the structure of a neurone; the establishment of the resting potential by the sodium-potassium pump; the generation of an action potential by voltage-gated channels (depolarisation and repolarisation); the all-or-nothing principle and the refractory period; saltatory conduction in myelinated neurones; and synaptic transmission by acetylcholine at a cholinergic synapse.
A focused answer to the OCR H420 5.1.3 dot point on neuronal communication. Covers neurone structure, the resting potential, the action potential and its ionic basis, the all-or-nothing principle and refractory period, saltatory conduction, and synaptic transmission by acetylcholine.
14 min answer →

How does a chloroplast capture light energy and use it to fix carbon dioxide into sugars?

5.2.1 Photosynthesis: the structure of the chloroplast; the light-dependent stage (photolysis of water, photophosphorylation and the reduction of NADP); the light-independent stage (the Calvin cycle, fixing carbon dioxide using RuBP, forming GP and TP and regenerating RuBP); and the effect of limiting factors (light intensity, carbon dioxide concentration and temperature).
A focused answer to the OCR H420 5.2.1 dot point on photosynthesis. Covers chloroplast structure, the light-dependent stage (photolysis, photophosphorylation and reduced NADP), the light-independent stage (the Calvin cycle with RuBP, GP and TP), and the effect of limiting factors.
14 min answer →

How do plants respond to their environment with hormones, and how does the mammalian nervous system control responses and muscle contraction?

5.1.5 Plant and animal responses: tropisms and the role of auxin (IAA) in phototropism; the structure and function of the mammalian nervous system (central and peripheral, voluntary and autonomic), the reflex arc and the fight-or-flight response; and the structure and the sliding filament mechanism of skeletal muscle contraction.
A focused answer to the OCR H420 5.1.5 dot point on plant and animal responses. Covers tropisms and the role of auxin in phototropism, the organisation of the mammalian nervous system, the reflex arc and fight-or-flight, and the sliding filament mechanism of muscle contraction.
13 min answer →

How do cells release energy from glucose in the four stages of aerobic respiration, and what happens without oxygen?

5.2.2 Respiration: the four stages of aerobic respiration (glycolysis, the link reaction, the Krebs cycle and oxidative phosphorylation); the role of decarboxylation, dehydrogenation, reduced NAD and FAD, the electron transport chain, chemiosmosis and ATP synthase; the synthesis of ATP and the role of oxygen as the final electron acceptor; and anaerobic respiration in animals (lactate) and in yeast (ethanol).
A focused answer to the OCR H420 5.2.2 dot point on respiration. Covers the four stages of aerobic respiration (glycolysis, the link reaction, the Krebs cycle and oxidative phosphorylation), chemiosmosis and ATP synthase, the role of oxygen, and anaerobic respiration producing lactate or ethanol.
14 min answer →