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LGS A-Level OCR Biology - Unit 6 - Ecosystems Part 1
This flashcard deck covers key concepts from Unit 6 of the OCR A-Level Biology curriculum, focusing on ecosystems. It includes definitions, factors affecting ecosystems, and the organization of ecosystems.
Ecosystem
All the interactions between the living and non-living components in a defined area
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Key Terms
Term
Definition
Ecosystem
All the interactions between the living and non-living components in a defined area
Biome
Large ecosystem
Open ecosystem
When living things can move between ecosystems
Closed ecosystems
When living things cannot easily move between ecosystems e.g. islands
Niche
Role of a particular species
Biotic
Involves other living organisms
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| Term | Definition |
|---|---|
Ecosystem | All the interactions between the living and non-living components in a defined area |
Biome | Large ecosystem |
Open ecosystem | When living things can move between ecosystems |
Closed ecosystems | When living things cannot easily move between ecosystems e.g. islands |
Niche | Role of a particular species |
Biotic | Involves other living organisms |
Biotic factors affecting ecosystems | Predators; Food supply (prey); Disease; Cooperation between species; Competition between species |
Abiotic factors affecting ecosystems | pH; Conc of pollutants; Temp (climatic); Moisture/ rainfall/ relative humidity; O2 level; Soil type (edaphic); Light intensities |
How does low light intensity affect the ecosystem | Plants develop photosynthetic pigments that require less light; Grow larger leaves; Reproductive systems that only work in optimum light intensities |
How does temp affect the ecosystem | Temp has the biggest effect on enzymes in the organisms that live in the ecosystem; May trigger migration/ hibernation; Dormancy/ leaf fall/ flowering in plants |
How are ecosystems organised | In trophic levels |
Producers in an ecosystem | Lowest trophic level; Involves autotrophs, chemotrophs and photoautotrophs |
Autotrophs | Convert energy from environment into complex organic matter, then are used as respiratory substrates or for growth |
Chemo/photoautotrophs | Use light/ chemicals to convert small inorganic molecules into complex organic ones |
Consumers | Higher/est trophic levels; Feed on complex organic matter made by autotrophs and other organisms and use the products of digestion as respiratory substrates or for growth; 1’<2’<3’ |
Decomposers | Feed on waste or dead organsims to gain energy by digesting and respiring organic matter
Recycling - returns inorganic ions to the air/soil |
Why are ecosystems dynamic | Always changing due to many interlaced intearctions that any small change causes several others–> alters flow of biomass |
Types of changes in ecosystems | Cyclical - repeated change e.g. seasons, day/night; Directional - in one direction e.g.global warming, erosion; Unpredictable/ erratic - no rhythm or constant direction e.g. volcanic eruption |
Trophic level | Level at which an organism feeds |
Components of an ecosystem | Habitat; Population; Community |
Habitat | Where an organism lives |
Population | Where all the members of a species living in some place at a given time |
Community | All the populations of diff species who live in some place at a given time, who can interact w/ each other |
Why are there fewer consumers at higher levels | Energy (biomass) is lost at each trophic level so unavailable to organism at next trophic level, therefore there’s less energy available to sustain living tissue |
How is biomass lost | Cellular respiration - conversion to inorganic molecules such as CO2 and H2O; Excretory materials; Indigestible matter; Not everything is fit for consumption e.g. bones; Transferred at metabolic heat (movement) |