Energy Transfer Flashcards
How is photosynthesis affected by limiting factors
There could be enough light but could not have enough CO2 for example. Therefore slowing down the rate
Define trophic level
A position in a food chain or ecological pyramid occupied by a group of organisms with similar feeding patterns
Net production equation
Gross production - respiratory losses
Define net productivity
Rate at which energy is stored
Define gross productivity
Quantity of energy converted by plants to organic matter
Why is there only a small percentage of energy passed on to the next trophic level
Some of available energy (60%) never taken in by organisms in first place. For example…
Plants can’t use all light energy that reaches its leaves ( in wrong wavelength, or only a small amount of light actually hits the leaves, some light may not reach the atmosphere
Not everything is being consumed (not everything can be eaten, eg bone)
Not everything they eat can be physically digested, a lot is excreted
The rest of the available energy (40%) is taken in (called gross productivity), again not all reaches next trophic level. Examples….
Warm blooded animals use energy for heat through respiration. Called respiratory loss
10% of the total energy available becomes biomass, called net productivity
Energy available is measured in…..
Kilojoules per metre per year
The equation for energy transfer is…
‘Energy available after transfer’ divided by ‘energy available before transfer’ times 100
Pyramids of numbers represent….
The number of organisms at each trophic level
Disadvantages of pyramids of numbers
No account of size (not always a pyramid shape)
Individual numbers alter hugely so can be difficult to represent on the same scale accurately
Info on pyramids of biomass
Show the amount of biomass in each trophic level at a single moment in time. More reliable than pyramids of number. Biomass is the total mass of plants, and/ or animals in a particular place. Biomass is usually measured in grams per square metre.
Disadvantages of pyramids of biomass
Seasonal variations are not obvious, causing some pyramids to be distorted in shape
Info on pyramids of energy
The most accurate pyramid representation. Shows the amount of energy available in each trophic level in kilojoules per square metre per year. The data is collected over a year over a square metre. This rules out the problem of an organism with the same biomass having different amounts of stored energy. They are always pyramid shaped
The main route by which energy enters an ecosystem is….
Photosynthesis
In pyramid diagrams, the area of each block tells you what
The size of the trophic level
