IB Biology HL 1-2 C4.2 Transfers of Energy & Matter PDF

C4.2 Transfers of Energy & Matter C4.2.1 - 2.16 IB Biology HL 1-2 C 4.2.1 Ecosystems as open systems in which both energy and matter can enter and exit Ecosystem: all of the organisms and abiotic factors in an area Ecosystems are open systems Open system: resources (m...

C4.2 Transfers of Energy & Matter C4.2.1 - 2.16 IB Biology HL 1-2 C 4.2.1 Ecosystems as open systems in which both energy and matter can enter and exit Ecosystem: all of the organisms and abiotic factors in an area Ecosystems are open systems Open system: resources (matter and energy) can enter and exit Closed system: energy can enter and exit, but matter cannot C 4.2.2 Sunlight as the principal source of energy that sustains most ecosystems Sunlight is the initial/primary energy source for most ecosystems Producers convert solar energy into chemical energy (photosynthesis) Cyanobacteria Plants Eukaryotic algae Light intensity and the proportion that is absorbed by producers varies Different global positions or different depths/conditions for aquatic environments Open caves - primary energy source may be dead things that flow into the cave Closed caves - chemosynthetic bacteria harness energy from chemical reactions C 4.2.3 Flow of chemical energy through food chains Start with producers and show feeding relationships Arrows symbolize the flow of energy Nothing feeds on the last organism in a food chain grass mouse snake C 4.2.4 Construction of food chains and food webs to represent feeding relationships in a community Food webs show all of the possible food chains in a community Organisms may be classified into different trophic levels Primary Primary Secondary producer consumer consumer carrot rabbit fox C 4.2.4 Construction of food chains and food webs to represent feeding relationships in a community Food webs show all of the possible food chains in a community Organisms may be classified into different trophic levels Primary Primary Secondary Tertiary producer consumer consumer consumer grain grasshopper bird fox C 4.2.5 Supply of energy to decomposers as carbon compounds in organic matter coming from dead organisms Decomposers get their energy from dead organisms, discarded body parts, and feces Recycle nutrients Saprotrophs: a type of decomposer that digests things externally Detritivores: decomposers that digest things internally C 4.2.6 Autotrophs as organisms that use external energy sources to synthesize carbon compounds from simple inorganic substances Autotroph: an organism that can synthesize all of the necessary carbon compounds itself using inorganic substances in the environment Carbohydrates, amino acids, fatty acids, steroids, nucleotides, etc. Plants, algae, cyanobacteria C 4.2.7 Use of light as the external energy source in photoautotrophs and oxidation reactions as the energy source in chemoautotrophs Autotrophs take inorganic substances from the environment and convert them into organic compounds, but this requires energy Anabolic reactions (condensation reactions) build large molecules Carbon fixation reactions in the Calvin Cycle (photosynthesis) Sunlight (used by photoautotrophs) Chemical reactions (used by chemoautotrophs) C 4.2.7 Use of light as the external energy source in photoautotrophs and oxidation reactions as the energy source in chemoautotrophs Iron is oxidized when exposed to air Oxidation reactions release energy Some organisms (iron oxidizing bacteria) can harness this energy Oxidation: loss of electrons The bacteria capture the electrons (get reduced) and use this in ways that are similar to ATP production in cellular respiration and ATP usage in the Calvin Cycle. C 4.2.8 Heterotrophs as organisms that use carbon compounds obtained from other organisms to synthesize the carbon compounds that they require Heterotroph: organisms that receives carbon compounds (and energy) by feeding on other organisms. Digestion: chemical breakdown of molecules (so they can be absorbed and used to make new compounds Internal: consume → digest → absorb → make new compounds External: release enzymes → digest → absorb → make new compounds C 4.2.9 Release of energy in both autotrophs and heterotrophs by oxidation of carbon compounds in cellular respiration All organisms need ATP All organisms produce ATP during cellular respiration All organisms oxidize carbon compounds to release energy and make ATP Autotrophs - make and oxidize their own carbon compounds Heterotrophs - oxidize carbon compounds they consume C4.2 Transfers of Energy Through Trophic Levels C4.2.10 - 2.16 IB Biology HL 1-02  C 4.2.10 Classification of organisms into trophic levels Trophic levels depend on where an organism is in a food chain carrot rabbit fox Primary Primary Secondary Tertiary producer consumer consumer consumer grain grasshopper bird fox C 4.2.11 Construction of energy pyramids Shows the amount of energy gained per year per unit of area in each trophic level 10% Rule → proportionally stepped/scaled, not triangular Secondary Label with trophic level, energy value, Consumers 300 kJm-2yr-1 and units Primary Draw and label an energy pyramid that Consumers includes four trophic levels and where 3,000 kJm-2yr-1 the producers have 30,000 kJm-2yr-1 Primary Producers 30,000 kJm-2yr-1 C 4.2.12 Reductions in energy availability at each successive stage in food chains due to large energy losses between trophic levels 90% About 90% of energy is “lost” between trophic levels Limits trophic levels 90% Reasons for energy loss: Secondary Consumers 1. Cellular respiration (fewer carbon 300 kJm-2yr-1 compounds available for oxidation + Primary heat loss) Consumers 2. Incomplete consumption (not every 3,000 kJm-2yr-1 part is eaten) 3. Incomplete digestion (not every part is Primary Producers 30,000 kJm-2yr-1 digestible) C 4.2.13 Heat loss to the environment in both autotrophs and heterotrophs due to conversion of chemical energy to heat in cell respiration. Conversion of chemical energy during respiration produces heat + HEAT This heat can be useful to some organisms (ex. Warm blooded animals like dogs and birds), but heat cannot be converted back into chemical energy so it cannot be passed on to the next trophic level. Constant energy flow is necessary for ecosystem sustainability. C 4.2.14 Restrictions on the number of trophic levels in ecosystems due to energy loss. Food chains can vary in length 90% lost at each step This limits: Fox biomass The amount of biomass at each Rabbit level biomass The number of trophic levels Carrot biomass C 4.2.15 Primary production as accumulation of carbon compounds in biomass by heterotrophs Growth and reproduction lead to an increase in biomass (carbon compounds) Fox Rabbit Carrot Carrot C 4.2.15 Primary production as accumulation of carbon compounds in biomass by heterotrophs GPP (gross primary production): total biomass of carbon compounds made during photosynthesis NPP (net primary production): the amount of biomass available to consumers due to the loss of biomass during respiration in plant cells Units gCm-2yr-1 Different biomes have different production capacities C 4.2.16 Secondary production as accumulation of carbon compounds in biomass by heterotrophs Secondary production: increase in biomass (carbon compounds) by heterotrophs Declines with each trophic level (fewer Secondary oxidizable carbon compounds) so you have Consumers less biomass per unit of area being Primary produced as you add levels Consumers Can increase productivity is we increase plant based diets. Primary Producers