Definitions
It shows the flow of energy through a sequence of organisms each of which feeds on the previous trophic level
What is a food chain?
The principal source of energy that sustains most ecosystems
What is sunlight?
Organisms that use carbon compounds obtained from other organisms to synthesize the carbon compounds that they require
What are heterotrophs?
Accumulation of carbon compounds in biomass by autotrophs
What is primary production?
During combustion of biomass, peat, coal, oil and natural gas
When is carbon dioxide released into the atmosphere?
A complex network of interconnected food chains that show the feeding relationships and energy flow between organisms in an ecosystem
What is a food web?
It is a graph that represents energy transfer and energy losses between trophic levels in food chains
What is a pyramid of energy?
Organisms, usually green plants, which obtain inorganic nutrients from the abiotic environment
What are autotrophs?
The accumulation of carbon compounds in biomass by heterotrophs
What is secondary production?
This occurs when photosynthesis exceeds respiration
When is there a net uptake of carbon dioxide?
Open systems in which both energy and matter can enter and exit
What is an Ecosystem?
By oxidation of carbon compounds in cell respiration
How is energy released in both autotrophs and heterotrophs?
They use light as their external energy source
What are photoautotrophs?
g m−2 yr−1
What is the unit of primary production?
A graph showing the annual fluctuation and long term trend in atmospheric carbon dioxide levels
What is a Keeling curve?
Organisms That feed on faeces, dead organisms and decaying matter
What are decomposers?
At each successive stage in food chains there are fewer organisms or smaller organisms. There is therefore less biomass, but the energy content per unit mass is not reduced.
Why are there a limited number of trophic levels in ecosystems?
They use oxidation reactions as their energy source, for example iron-oxidising bacteria
What are chemoautotrophs?
Because there is a loss of biomass when carbon compounds are converted to carbon dioxide and water in cell respiration.
Why is secondary production lower than primary production in an ecosystem?
When respiration exceeds photosynthesis
When is there a net release of carbon dioxide?