Transfer of Solar Energy 1. Solar energy is radiated from the Sun. Upon reaching the Earth, this is reflected back into space by the atmosphere, absorbed by the Earth and absorbed by plants (1%). 2. Primary producers (autotrophs) convert solar energy into chemical energy through photosynthesis. They use this energy for respiration and bodily processes. 3. Autotrophic producers are eaten by consumers. This causes organic compounds and energy to be transferred from plants to animals. 4. Decaying consumers and autotrophs are broken down by decomposers and detritivores. Detritivores feed on detritus (debris from decomposing matter) and decomposers feed on decomposing organisms. Decomposers also release enzymes which breaks the nutrients into inorganic molecules to go into the soil. Note, nutrients are recycled here, not energy. 5. Energy is lost to the environment as heat. As energy cannot be created in a food chain, the trophic levels are limited. Trophic Levels Trophic levels are a feeding level in a food chain. This describes the position of producers and consumers in a food chain. Transformation of Solar Energy Converting Light to Chemical Energy Light is converted to chemical energy through photosynthesis. In this, producers absorb red and blue lights. This is used to excite chlorophyll pigments, powering photosynthesis. Photosynthesis then converts solar energy into usable chemical energy, allowing it to be recycled through the food chain. 6CO2 + 6H2 O → C6 H12 O6 + 6O2 Producing Biomass Biomass is the mass of biological organisms in a given area or ecosystem at a given time. In the textbook, biomass is defined as the amount of organic matter in a system. Biomass is created when the organic matter produced by autotrophs through photosynthesis is in excess of what is needed to sustain life. Primary production: refers to the production of organic matter produced by photosynthetic plants. It is expressed as the rate of biomass production. Secondary production: refers to the building of tissue by heterotrophs after ingesting autotrophic producers. It may involve animals eating plants, animals eating animals or decomposers breaking down carcasses. It is also expressed as the rate of biomass production. In a productive environment, living plant or animal tissue will accumulate over time. Biomass is the amount of this accumulated material, while production is the rate of increase of the total biomass. For more detail, go to this link. Carbon Cycle The carbon cycle describes the processes used to transfer carbon from one form to another. This occurs through the following processes: Carbon in the ground - Photosynthesis: CO2 is converted to organic matter Feeding: carbon moves between animals and plants along food chains. Fossilisation: dead organisms are compressed over millions of years to form fossil fuels or carbon stores such as limestone - Decomposition: carbon compounds in dead organisms, urine and faeces are broken down by decomposers Carbon in the atmosphere - Combustion: when fossil fuels are burned, CO2 is released into the atmosphere - Respiration: organisms release CO2 into the atmosphere through respiration The Carbon Cycle and Biomass Plants on land and in the ocean convert carbon dioxide to biomass through photosynthesis. The carbon returns to the atmosphere when plants decay, are eaten and digested by animals (respiration) or burn in fires. As such, the carbon cycle is connected to the ecosystems. Plants may bloom earlier in the year if the climate assists growth. This takes more carbon out of the atmosphere. Plants may have slow growth. This means that more carbon will go into the atmosphere.
