All Home page Biology Chemistry Physics Biology - 4.1.1: Cell Structure Biology - 4.1.2: Cell Division Biology - 4.1.3: Stem Cells Biology - 4.1.3: Transport in cells Biology - 4.2.2: Animal tissues, organs and organ systems Biology - Topic 4.2.3: Plant tissues, organs and systems Subscriptions Biology - 4.3.1: Infection and response Biology - 4.3.2: Monoclonal antibodies (biology only) (HT only) Biology - 4.3.3: Plant disease (biology only) Biology - 4.4.1 : Photosynthesis Biology - 4.4.2 : Respiration Biology - 4.5.1: Homeostasis Biology - 4.5.2: The human nervous system Biology - 4.5.3: Hormonal coordination in humans Biology - 4.5.4: Plant hormones (biology only) Biology - 4.6.1: Reproduction Biology - 4.6.2: Variation and evolution Biology - 4.6.3: The development of understanding of genetics and evolution Biology - 4.6.4: Classification of living organisms Biology - 4.7.1: Adaptations, interdependence and competition Biology - 4.7.2: Organisation of an ecosystem Biology - 4.7.3: Biodiversity and the effect of human interaction on ecosystems Biology - 4.7.4: Trophic levels in an ecosystem (biology only) Biology - 4.7.5: Food production (biology only) Biology - 4.2.1: Organisation Chemistry - 4.1.1 A simple model of the atom, symbols, relative atomic mass, electronic charge and isotopes Chemistry - 4.1.2 The periodic table Chemistry - 4.1.3 Properties of transition metals Chemistry - 4.2.1 Chemical bonds, ionic, covalent and metallic Chemistry - 4.2.2 How bonding and structure are related to the properties of substances Chemistry - 4.2.3 Structure and bonding of carbon Chemistry - 4.2.4 Bulk and surface properties of matter including nanoparticles Chemistry - 4.3.1 Chemical measurements, conservation of mass and the quantitative interpretation of chemical equations Chemistry - 4.3.2 Use of amount of substance in relation to masses of pure substances Chemistry - 4.3.3 Yield and atom economy of chemical reactions Chemistry - 4.3.4 Using concentrations of solutions in mol/dm3 Chemistry - 4.3.5 Use of amount of substance in relation to volumes of gases Chemistry - 4.4.1 Reactivity of metals Chemistry - 4.4.2 Reactions of acids Chemistry - 4.4.3 Electrolysis Chemistry - 4.5.1 Exothermic and endothermic reactions Chemistry - 4.5.2 Chemical cells and fuel cells Chemistry - 4.6.1 Rate of reaction Chemistry - 4.6.2 Reversible reactions and dynamic equilibrium Chemistry - 4.7.1 Carbon compounds as fuels and feedstock