Uploaded byMariam Ohanyan
Topic 4.2 Energy Flow
The document discusses the flow of energy through ecosystems, emphasizing that ecosystems rely on sunlight for energy, which is converted into chemical energy via photosynthesis. It outlines the roles of food chains and food webs, explaining trophic levels and the loss of energy at each level, along with the importance of saprotrophic organisms in recycling nutrients. The document also addresses ecological productivity, including the definitions of primary and secondary production, and the concepts of biomagnification and bioaccumulation in the context of pollutants.
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Topic 4.2 Energy Flow
- 1. Topic 4.2 EnergyFlow "Shirakatsy Lyceum" International Scientific Educational Complex The International Baccalaureate Diploma Programme
- 2. Understandings: Most ecosystemsrely on a supply of energy from sunlight Light energy is converted to chemical energy in carbon compounds by photosynthesis Chemical energy in carbon compounds flows through food chains by means of feeding Energy released from carbon compounds by respiration is used in living organisms and converted to heat Living organisms cannot convert heat to other forms of energy Heat is lost from ecosystems Energy losses between trophic levels restrict the length of food chains and the biomass of higher trophic levels
- 3. Photosynthesis Photosynthesis, theprocess by which green plants and certain other organisms transform light energy into chemical energy. During photosynthesis in green plants, light energy is captured and used to convert water, carbon dioxide, and minerals into oxygen and energy-rich organic compounds.
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- 5. Describe what ismeant by a food chain, giving three examples, each with at least three linkages (four organisms) A food chain shows the direction of energy flow from one species to another. For example, an arrow from A to B means that A is being eaten by B and therefore indicates the direction of the energy flow.
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- 7. Describe what is meantby a food web. A food web is a diagram that shows all the feeding relationships in a community with arrows which show the direction of the energy flow
- 8. 1/23/2018By Mariam OhanyanSource: https://socratic.org/questions/which-represents-an-ecosystem-better-a-food-chain-or-food-web-why
- 9. Define trophic level Theposition an organism occupies within a feeding sequence is known as a trophic level. • Producers always occupy the first trophic level in a feeding sequence • Primary consumers feed on producers and hence occupy the second trophic level • Further consumers (e.g. secondary, tertiary, etc.) may occupy subsequent trophic levels
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- 11. Explain the energyflow in a food chain. Energy flows from producers to primary consumers, to secondary consumers, to tertiary consumers... Energy is lost between trophic levels in the form of heat through cell respiration, faeces, tissue loss and death. Some of this lost energy is used by detritivores and saprotrophs. These in turn also lose energy in the form of heat through cell respiration.
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- 13. Explain that energyenters and leaves ecosystems, but nutrients must be recycled Energy is not recycled. Constantly being supplied to the ecosystem through light energy. Energy is lost from the ecosystem in the form of heat through cell respiration. Nutrients must be recycled as there is only a limited supply of them. They are absorbed by the environment, used by organisms and then returned to the environment. Carbon, nitrogen and phosphorus are all examples of nutrients. There is only a limited supply of these as they are not resupplied to the ecosystems like energy. Therefor they have to be recycled over and over. They are absorbed from the environment, used by living organisms and then returned to the environment.
- 14. Energy Transformations inLiving Organisms Source: http://science.jrank.org/kids/pages/59/ALL-ABOUT-ENERGY.html
- 15. Energy loss Plants useonly a tiny amount of the energy that comes from the Sun. Some energy goes back into space. Some warms the land and oceans. Only 1 or 2 percent of the energy from the Sun is absorbed by plants. Plants do not turn all this energy into new growth. Only about a tenth of the energy becomes plant material. So animals that eat plants get only a tenth of the energy that the plant got from the Sun. Like plants, animals lose a lot of the energy they get from plants they eat. They turn only about a tenth of the energy they get from plants into meat. So animals that eat other animals get only a thousandth of the energy that the plant got from the Sun. Each stage of the food chain has less energy than the one before it. Because of this, there are more plants than plant-eating animals. And there are more animals that eat plants than animals that eat meat.
- 16. State that saprotrophicbacteria and fungi (decomposers) recycle nutrients Saprotrophic bacteria and fungi (decomposers) recycle nutrients. These organisms feed on dead organisms and products of living organisms. They secrete enzymes on these materials that cause decomposition, and then they absorb decomposed and digested foods. They absorb only what they need to survive, the remainder of the nutrients are reabsorbed into the ecosystem. They are essential as they unlock these nutrients, readying them for reabsorption. Examples include many species of bacteria and fungi. These are essential organisms to an ecosystem, since they cause recycling of materials between biotic and abiotic parts of the ecosystem.
- 17. Ecological productivity Inecology, production (or productivity) refers to the rate of generation of biomass in an ecosystem It is usually expressed in units of mass per area per time (e.g. kg m–2 day–1)
- 18. Primary Production Primaryproduction describes the production of chemical energy in organic compounds by producers The main source of energy for primary production is sunlight, but a fraction may be driven by chemosynthesis by lithotrophs Primary production may be categorized as one of two types: Gross primary production (GPP) is the amount of chemical energy as biomass that a producer creates in a given length of time Net primary production (NPP) is the amount of chemical energy that is not consumed by respiration (NPP = GPP – respiration) Secondary Production Secondary production describes the generation of biomass by heterotrophic organisms (consumers) This biomass generation is driven by the transfer of organic compounds between trophic levels via feeding Secondary production may also be categorized according to gross (total) and net (usable) amounts of biomass
- 20. Ecological Pyramids Pyramid of Numbers Apyramid of numbers shows the relative number of organisms at each stage of a food chain Pyramid of Biomass A pyramid of biomass shows the total mass of organisms at each stage of a food chain Pyramid of Energy A pyramid of energy shows the amount of energy trapped per area in a given time period at each stage of a food chain
- 21. 1/23/2018By Mariam OhanyanSource: http://slideplayer.es/slide/4115799/
- 22. Biomagnification Because energytransformations are only ~10% efficient, higher trophic levels must consume more prey to meet energy needs If a pollutant is ingested by living organisms, it will become concentrated at higher trophic levels as they eat more exposed prey The increase of a substance (such as a pollutant) in a particular organisms is called bioaccumulation The increase in the concentration of a substance at a particular trophic level is called biomagnification
- 23. Bioaccumulation Refers tohow pollutants enter a food chain, whereas biomagnification refers to the tendency of pollutants to concentrate as they move from one trophic level to the next
- 24. Because pollutantsbecome concentrated by biomagnification, higher trophic levels are more susceptible to their toxic effects The pesticide DDT caused egg-shell thinning and population declines in species of birds that fed on exposed insects Heavy metals (like mercury) released into waterways via industrial processes may become concentrated in fish
- 25. 1/23/2018By Mariam OhanyanSource: https://themercurysite.com/caddo-lake/biomagnification/
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