BY5.7 - Energy and Ecosystems Flashcards
What is an ecosystem?
All the /biotic/ and /abiotic/ /factors/ in an area
What is a habitat?
The /environment/ where an /organism/ normally /lives/
What is a community?
The /different populations/ of /species/ living in a /particular habitat/
What is a population?
A /group of organisms/ of the /same species living/ in a /particular area/ that can /interbreed/
what is usually the source of energy in all ecosystems?
sunlight
What is photosynthesis?
The /route/ by which /light energy is converted into /chemical energy/ - e.g. /organic compounds - glucose/ and is /made available to organisms within an ecosystem/
What are (primary) producers?
Organisms that convert light energy into chemical energy base of every food chain found within every ecosystem
Why is not all the light energy that reaches the leaf converted into chemical energy?
1) light reflected by leaf surface 2) light not absorbed (chlorophyll only absorbs red + blue wavelengths) 3) light is transmitted through the leaf (without hitting chlorophyll) 4) photolysis - light is absorbed by water
What is photosynthetic efficiency?
A measure of how well a plant is able to capture light energy Energy converted into photosynthesis products P.E = ——————————————————– total light energy falling on plant
What is gross primary productivity?
The total amount/rate of which organic compounds are produced by photosynthesis.
What is net primary productivity?
The produce that is left after some of the GPP has been used by the plant in respiration NPP = GPP - Energy used by the plant in respiration
What does Net Primary Productivity represent?
food available to consumers
What is succession?
The change in structure and composition of communities over time
What is primary succession?
Start: Bare rock/sand - e.g. volcanic eruption/retreating glacier
What is Secondary succession?
STARTS WITH SOIL -FEW/ NO SPECIES e.g FOREST CLEARING following FOREST FIRE
How does the starting harsh abiotic environment become habitable through succession?
1) bare rock colonised by PIONEER SPECIES - LICHEN/BACTERIA 2) PIONEERS erode rock - form thin soil 3) ORGANIC MATTER accumulates from DEAD LICHENS/BACTERIA 4) community replaced by MOSSES/FERNS 5) replaced by GRASSES 6) MORE HABITATS available - SMALL ANIMALS join community 7) BIODIVERSITY INCREASES 8) SHRUBS AND BUSH community arrives 9) CLIMATE COMMUNITY - WOODLAND
What human activities can prevent the climax community from being established?
1) Sheep grazing 2) quarrying/ mining 3) deforestation - soil erosion
what happens as the climax community is approached?
1) increase in SPECIES DIVERSITY –> more niches 2) increase in GPP/NPP –> Increase in PLANT BIOMASS 3) more species = more COMPLEX FOOD WEBS = Habitat becomes MORE STABLE (more to feed on) 4) Biotic factors have more of an effect on determining species present e.g. competition/predatation/disease
