Theme 2 - Energy and Matter Past Paper PDF

Okay, here's the conversion of the provided text into a structured markdown format. ## Theme 2: Fluid of energy and matter ### 1. Routes of penetration of the atmospheric energy #### Solar energy * It controls the terrestrial systems, governing the climatic, hydrological, and ecological cycles....

Okay, here's the conversion of the provided text into a structured markdown format. ## Theme 2: Fluid of energy and matter ### 1. Routes of penetration of the atmospheric energy #### Solar energy * It controls the terrestrial systems, governing the climatic, hydrological, and ecological cycles. * In a desert region like the Sahara, solar energy causes strong evaporation, influencing local hydrological cycles. #### Ways of Penetration of Energy * Conversion of light energy into chemical energy (photosynthesis). * Agricultural field crops of choice use solar light for photosynthesis to produce sugars in grains. * Transfer of chemical energy from one trophic level to another. * A food chain transforms this chemical energy into heat. * Conversion of visible light into heat. * Rocks exposed to sunlight become hot during the day and release heat at night * Release of thermal energy into the atmosphere * A dense forest like the Amazon absorbs a lot of sunlight and retains part of it as heat. ### 2. Transfers and transformation of energy Energy enters as light, transforms into biomass through photosynthesis, and circulates between trophic levels. A portion of energy is lost as heat at each level. When a rabbit eats grass he uses some of the energy to maintain its functions but most of it dissipates as heat. #### Ecological efficiency Percentage of energy transferred from a trophic level to another, calculated as the ratio between matrix energy (new biomass) and energy source provided: $\frac{Energy\; used\; for\; growth}{Energy\; source\; provided} \times 100$ * Gross, net, primary and secondary Productivity. * Biomass: total mass of living organisms. * Productivity: rate of conversion of energy into biomass over a given period $(J/m^2 / year)$. * Gross primary productivity (GPP): total energy fixed by photosynthesis on a given surface, for a period of time. * Net primary productivity (NPP): energy remaining for consumers after deducting the respiratory parts of plants. $NPP=GPP-R$ Productivité secondaire brute (CPSB): total energy stored by consumers after deductions of excretions $PSD = Food\; ingested -Secretions$ * Net secondary productivity (PSN): Energy available to consumers once respiratory losses are deducted $PSN = PSP-R$ **Reforestation** (planting trees) : soil with leaves = rapid recolonization of herbs and grasses. ### 5. Study of Ecosystems #### Carbon Cycle Describes the circulation of carbon between living organisms and their environments. * Photosynthesis: Plants consume $CO_2$ from the atmosphere to produce glucose. * Respiration: Animals consume glucose and release $CO_2$ * Decomposition: Decomposers transform organic matter into $CO_2$ * Decomposition of wetlands releases $CO_2$. * Combustion: The combustion releases $CO_2$. * Absorption from the oceans: Atmospheric $CO_2$ dissolves in the oceans, forming carbonates. #### Human impacts on the carbon cycle: * Deforestation: less vegetation to absorb $CO_2$ * Combustion of fossil fuels: increased release of gases * Acidification of the oceans: $CO_2$ dissolves, making oceans more acid. ### Cycle of Azote Essentially for the formation of proteins and DNA in living organisms: * Azote ($N_2: Nitrogen$) represents 70% and is of litlle use in this form. * Micro organisms are used for the plants: #### Fixation of Azote: Azote transforms in Ammonique $(NH_4^+)$ through bacteries. * legumes (peas, haricots...) azote bacteries for azote (N) bacteria. * Nitrification : bacteries transforms en nitrogen (NO) nitritos (NO₂) * Asorbtion par les plantes: aborbent les nitrates et syntethisent les proteines. * Consommation: les animaux et les herbivores mangent des plantes et ils sont transformés en éléments utiles pour les consommateurs * dénitrification: les nitrates (NO2) retournent dans l'atmosphère. * Decomposition : decomposers transforme en matière organique. #### Impacle humain: * l'agriculture intensive entraine une polution des nutribes dont l'azote. * Activités industrielles contribuent à plus d'azote dan l'atmosphere.