Syllabus concepts to know

• C4.2.1 Ecosystems as open systems in which both energy and matter can enter and exit
• C4.2.2 Sunlight as the principal source of energy that sustains most ecosystems
• C4.2.3 Flow of chemical energy through food chains
• C4.2.4 Construction of food chains and food webs to represent feeding relationships in a community
• C4.2.5 Supply of energy to decomposers as carbon compounds in organic matter coming from dead organisms
• C4.2.6 Autotrophs as organisms that use external energy sources to synthesize carbon compounds from simple inorganic substances
• C4.2.7 Use of light as the external energy source in photoautotrophs and oxidation reactions as the energy source in chemoautotrophs
• C4.2.8 Heterotrophs as organisms that use carbon compounds obtained from other organisms to synthesize the carbon compounds that they require
• C4.2.9 Release of energy in both autotrophs and heterotrophs by oxidation of carbon compounds in cell respiration
• C4.2.10 Classification of organisms into trophic levels
• C4.2.11 Construction of energy pyramids
• C4.2.12 Reductions in energy availability at each successive stage in food chains due to large energy losses between trophic levels
• C4.2.13 Heat loss to the environment in both autotrophs and heterotrophs due to conversion of chemical energy to heat in cell respiration
• C4.2.14 Restrictions on the number of trophic levels in ecosystems due to energy losses
• C4.2.15 Primary production as accumulation of carbon compounds in biomass by autotrophs
• C4.2.16 Secondary production as accumulation of carbon compounds in biomass by heterotrophs
• C4.2.17 Constructing carbon cycle diagrams
• C4.2.18 Ecosystems as carbon sinks and carbon sources
• C4.2.19 Release of carbon dioxide into the atmosphere during combustion of biomass, peat, coal, oil and natural gas
• C4.2.20 Analysis of the Keeling Curve in terms of photosynthesis, respiration and combustion
• C4.2.21 Dependence of aerobic respiration on atmospheric oxygen produced by photosynthesis, and of photosynthesis on atmospheric carbon dioxide produced by respiration
• C4.2.22 Recycling of all chemical elements required by living organisms in ecosystems