IB HomeStandard LevelTopic 1: Statistical AnalysisTopic 2: CellsTopic 3: Chemicals of LifeTopic 4: GeneticsTopic 5: Ecology and Evolution5.1 Communities & EcosystemsTopic 6: Health & PhysiologyHigher LevelTopic 7: Nucleic Acid & ProteinTopic 8: Respiration & Picture ..Topic 9: Plant ScienceTopic 10: GeneticsTopic 11: Health & PhysiologyOptionsOption A: Nutrition & HealthOption B: Physiology of ExerciseOption C: Energy and also CellsOption D: EvolutionOption E: Neurobiology & Behav..Option F: Microbes & Biotech..Option G: Ecology & Conservat..Option H: More PhysiologyMore Resources

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5.1 Communities and also Ecosystems


5.1.1 Define species, habitat, populace, neighborhood, ecosystem and ecology

Species:  A group of organisms that deserve to interbreed and create productive, viable offspring

Habitat:  The atmosphere in which a species commonly stays or the location of a living organism

Population: A group of organisms of the very same species that live in the same area at the very same time

Community: A group of populations living and communicating via each various other in an area

Ecosystem: A community and its abiotic environment

Ecology:  The research of relationships in between living organisms and also in between organisms and their environment

5.1.2 Distinguish between autotroph and also heterotroph

Autotroph:  An organism that synthesises its organic molecules from easy inorgance substances (e.g. CO2 and also nitrates) - autotrophs are producers

Heterotroph: An organism that obtains organic molecules from various other organisms - heterotrophs are consumers

5.1.3 Distinguish between consumers, detritivores and saprotrophs

Consumer:  An organism that ingests other organic matter that is living or recently killed

Detritivore: An organism that ingests non-living organic matter

Saprotroph: An organism that stays on or in non-living organic matter, secreting digestive enzymes right into it and also soaking up the commodities of digestion

5.1.4 Decribe what is intended by a food chain, offering three examples, each through at leastern 3 linkperiods (four organisms)

A food chain mirrors the direct feeding relationships between species in a community

The arrows reexisting the transport of energy and also matter as one organism is consumed by one more (arrows allude in the direction of power flow)

The initially organism in the sequence is the producer, complied with by consumers (1°, 2°, 3°, etc.)

Examples of Food Chains


5.1.5 Describe what is intended by a food web

A food web is a diagram that mirrors how food chains are attached together into even more complex feeding relationships within a community

Tright here deserve to be more than one producer in a food web, and also consumers have the right to occupy multiple positions (trophic levels) 

5.1.6 Define trophic level

An organism"s trophic level refers to the place it occupies in a food chain

Producers constantly occupy the initially trophic level, while saprotrophs would certainly primarily occupy the ultimate trophic level of a offered food chain or food web

The trophic levels in a neighborhood are:

5.1.7 Deduce the trophic levels of organisms in a food internet and also food chain

The trophic level of an organism deserve to be figured out by counting the variety of feeding relationships coming before it and adding one (producer always first) 

Trophic Level = Number of arrows (in sequence) before organism + 1

In food webs, a single organism may occupy multiple trophic levels

5.1.8 Construct a food web containing approximately 10 organisms, utilizing appropriate information

Hint: When building a food web, constantly try to place an organism family member to its highest trophic level (to store all arrows pointing in same direction)

Food internet (trophic levels in red)


5.1.9 State that light is the initial power resource for almost all communities

All green plants, and some bacteria, are photo-autotrophic - they usage light as a resource of power for synthesising organic moleculesThis provides light the initial source of power for practically all communities Some bacteria are chemo-autotrophic and use energy derived from chemical procedures (e.g. nitrogen-fixating bacteria)

5.1.10 Explain the energy flow in a food chain

Energy enters many neighborhoods as light, where it is took in by autotrophs (e.g. plants) and converted right into chemical power using photosynthesisEnergy then gets passed to the primary consumer (herbivore) when they eat the plant, and then gets passed to successive consumers (carnivores) as they are eaten in turnOnly ~10% of energy is passed from one trophic level to the next, the remainder is lost Because ~90% of energy is shed between trophic levels, the variety of trophic levels are limited as energy flow is decreased at better levels

Rundown of Energy Flow in a Food Chain


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5.1.11 State that energy changes are never 100% efficient

When energy revolutions take area in living organisms the procedure is never 100% efficientUsually, energy changes in living points are ~10% effective, via around 90% of the energy lost in between trophic levelsThis energy may be lost as heat, be supplied up during cellular respiration, be excreted in faeces or reprimary unconsumed as the unconsumed component of food

5.1.12 Exordinary the factor for the form of pyramids of energy

A pyramid of energy is a graphical representation of the amount of power of each tropic level in a food chainThey are expressed in units of energy per location per time (e.g. kJ m2 year -1)Pyramids of power will certainly never show up inverted as some of the energy stored in one resource is constantly lost once moved to the next sourceThis is an application of the second legislation of thermodynamicsEach level of the pyramid of energy must be about one tenth the dimension of the level coming before it, as energy revolutions are ~10% efficient

5.1.13 Explain that power enters and leaves ecodevices, yet nutrients should be recycled

The motion of energy and issue with ecosystems are related because both occur by the transfer of substances through feeding relationshipsHowever before, energy cannot be recycled and also an ecodevice have to be powered by a constant influx of brand-new energy from an exterior source (e.g the sun)Nutrients describe material forced by an organism, and are constantly being recycled within an ecomechanism as food (either living or dead)The autotrophic tasks of the producers (e.g. plants) create organic materials from inorganic resources, which are then fed on by the consumersWhen heterotrophic organisms die, these inorganic nutrients are returned to the soil to be reprovided by the plants (as fertiliser)Hence power flows via ecosystems, while nutrients cycle within them

5.1.14 State that saprotrophic bacteria and fungi (decomposers) recycle nutrients

In order for organisms to thrive and reproduce, they need a supply of the elements of which they are made The saprotrophic task of decomposers (particular bacteria and fungi), free not natural products from the dead bodies and also waste commodities of organisms, ensuring a consistent supply of raw materials for the producers (which have the right to then be ingested by consumers)Thus saprotrophic bacteria and fungi play an essential function in recycling nutrients within an ecosystem