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Communities & Ecosystems Stephen Taylor
IB Diploma Biology Stephen Taylor Photo: Wasp in Java, by Stephen Taylor ©
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Assessment Statements Obj.
5.1.1 Define species, habitat, population, community, ecosystem & ecology. 1 5.1.2 Distinguish between autotroph and heterotroph. 2 5.1.3 Distinguish between consumers, detritivores and saprotrophs. 5.1.4 Describe what is meant by a food chain, giving three examples, each with at least four linkages. 5.1.5 Describe what is meant by a food web. 5.1.6 Define trophic level. 5.1.7 Deduce the trophic level of an organism in a food chain & food web. 3 5.1.8 Construct a food web containing up to 10 organisms, using appropriate information. 5.1.9 State that sunlight is the initial energy source for almost all communities. 5.1.10 Explain the energy flow in a food chain. 5.1.11 State that energy transfers are never 100% efficient. 5.1.12 Explain reasons for the shape of a pyramid of energy. 5.1.13 Explain that energy enters and leaves ecosystems, but nutrients must be recycled. 5.1.14 State that saprotrophic bacteria and fungi (decomposers) recycle nutrients. Command terms: Assessment statements from: Online IB Biology Subject Guide
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Food webs show all of the feeding relationships within a habitat.
Read this research article and generate a food web. The state of the oceans, part 2: Delving deeper into the sea's bounty. John Tibbetts This is a good thing.
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Food webs show all of the feeding relationships within a habitat.
Read this research article and generate a food web. The state of the oceans, part 2: Delving deeper into the sea's bounty. John Tibbetts This is a good thing.
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Food webs show all of the feeding relationships within a habitat.
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Food webs show all of the feeding relationships within a habitat.
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Outline the roles of bacteria in the nitrogen cycle.
(Total 6 marks)
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Rhizobium / nitrogen-fixing bacteria lives in root nodules / symbiotic relationship with legumes; fixes nitrogen into ammonia; using energy from ATP; Azotobacter / nitrogen-fixing bacteria lives free in soil; fixes nitrogen into ammonia; Nitrosomonas / nitrifying bacteria converts ammonia to nitrite; Nitrobacter / nitrifying bacteria converts nitrite to nitrate; Nitrosomonas and Nitrobacter live in well aerated soil / require good supply of oxygen; Pseudomonas denitrificans / denitrifying bacteria converts nitrate to nitrogen; nitrate is used as terminal electron acceptor instead of oxygen; carries this out in low oxygen / badly aerated soil; 6 max Responses must include at least three types of bacteria to achieve full marks. Award [0] for responses with just the name of bacterium.
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Explain how energy and nutrients enter, move through, and exit a food chain in an ecosystem.
(Total 8 marks)
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energy enters from (sun)light; chloroplasts / plants / producers / autotrophs capture (sun)light; energy flows through the trophic levels / stages in food chain; energy transfer is (approximately) 10% from one level to the next; heat energy is lost through (cell) respiration; energy loss due to material not consumed / assimilated / egested / excreted; labelled diagram of energy pyramid; energy passes to decomposers / detritivores / saprotrophs in dead organic matter; nutrient cycles within ecosystem / nutrients are recycled; example of nutrient cycle with three or more links; nutrients absorbed by producers / plants / roots; nutrients move through (food chain) by digestion of other organisms; nutrients recycled from decomposition of dead organisms; nutrients from weathering of rocks enter ecosystem; nutrients lost by leaching / sedimentation (eg shells sinking to sea bed); 8 max (Plus up to [2] for quality)
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Click here for more information about Biology4Good charity donations. @IBiologyStephen This is a Creative Commons presentation. It may be linked and embedded but not sold or re-hosted.
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