3.5.3 Energy and Ecosystems Flashcards
How do plants use the sugar from photosynthesis?
Primarily as respiratory substrates
TO synthesise other biological molecules eg. Cellulose
What is biomass?
Total dry mass of tissue or mass of carbon measured over a given times
Suggest the units for biomass.
Area being sampled: gm-2
Volume being samples: gm-3
How can the chemical energy store in dry mass be estimated?
Using calorimetry
Energy released = SHC of water x volume of water x temperature increase of water
Define gross primary production (GPP)
Total chemical energy in plant biomass within a given volume or area
Define net primary productivity (NPP)
The total chemical energy available for plant growth, plant reproduction and energy transfer to other tropic levels after respiratory losses
Formula between GPP and NPP
NPP = GPP - R
Where R represents respiratory losses
How can net production of consumers be calculated?
N = I - (F + R)
I : chemical energy from ingested food
F : energy lost as faeces and urine
R : respiratory losses
Why does biomass decrease along a food chain?
Energy lost in nitrogenous waster & urine
Some of the other organism is not consumed
Energy lost to surroundings as heat
Define primary and secondary productivity
Rate of primary or secondary production
Biomass in a specific area over a given time period
Outline some common farmin practices used to increase the efficiency of energy transfer
- Exclusion of predators: no energy lost to other organisms in food web
- Artifical heating: reduce energy lost to maintain constant body temperature
- Restriction of movement
- Feeding is controlled at the optimum
Give a general equation of % efficiency
Energy converted to a useful for / total energy supplied x 100
Explain why the length of food chains is limited
Energy is lost at each tropic level
SO there is insufficient energy to support a higher tropic level
What is a pyramid of biomass?
Diagram that shows the biomass at each trophic level
