13.2 energy transfer and productivity Flashcards
How much of the suns energy does a plant convert into organic matter?
1-3%
Why do plants convert only 1-3% of the suns energy into organic matter? 4 reasons
Over 90% of the suns energy reflected back into space.
Not all wavelengths can be absorbed.
Light may not fall on chlorophyll molecule.
A factor may limit the rate of photosynthesis e.g. CO2 concentration.
What is Gross Primary Production (GPP)?
Total quantity of chemical energy
stored in plant biomass
in a given area or volume.
What is Net Primary Productivity (NPP)
Chemical energy store left after plants use energy in respiration (20-50% of GPP)
How to calculate Net Primary Production?
Net Primary Production = Gross Primary Production - respiratory loss
What is Net Primary Productivity available for? 3 things
plant growth
reproduction
available to other trophic levels in ecosystem
How much NPP of the producer can be used by primary consumers for growth?
less than 10%
How much NPP of the primary consumer can be used by secondary/tertiary consumers for growth?
up to 20%
Why is energy lost between
producers -> primary consumers
primary consumers -> secondary consumers
secondary consumers -> tertiary consumers
3 reasons
Some of the organism not consumed
Some parts are indigestible, straight to faeces
Some energy is lost through excretion/respiration (heat)
How to calculate Net Production of consumers
Net Production of consumers =
chemical energy store of ingested food -
(energy lost through faeces + energy lost in respiration)
N=I-(F+R)
How is Efficiency % calculated?
Efficiency % = energy available after transfer / energy available before transfer x 100
Purpose of intensive farming?
As much energy from respiration as possible goes into growth.
4 Examples of intensive farming methods
Restricted movement (less muscle contraction)
environment kept warm (reducing heat loss)
feeding controlled (optimum amount and type)
predators excluded
