Energy and ecosystems (13) Flashcards
What are 2 ways plants use sugars from photosynthesis?
- primarily used as respiratory substances
- to synthesise other biological molecules e.g. cellulose
What is biomass?
total dry mass of a tissue (or twice the mass of carbon) measured over a given time in a specific area
What are the units of biomass when area is being sampled?
gm-2
What are the units of biomass when volume is being sampled?
gm-3
What is the equation for how the chemical energy store in dry biomass is estimated using calorimetry?
energy released = specific heat capacity of water x water volume x temperature increase of water
What type of calorimetry is preferable to simple calorimetry and why?
bomb calorimetry because it reduces heat loss to surroundings
How can you ensure all water is removed from a sample?
heat sample and reweigh until mass reading is constant
What is the equation for NPP?
NPP = GPP - R
What does the R stand for in NPP = GPP - R?
respiratory losses
What does GPP stand for?
gross primary production
What is meant by gross primary production?
total chemical energy in plant biomass within a given volume or area
What does NPP stand for?
net primary production
What is meant by net primary production?
total chemical energy available for plant growth, plant reproduction, and energy transfer to other trophic levels after respiratory losses
What is a pyramid of biomass?
diagram showing biomass at each trophic level
Why is a pyramid of biomass preferable to a pyramid of numbers?
the shape of a pyramid of numbers may be skewed since a small number of producers can support many consumers
What are 4 reasons why most of the suns energy is not converted to organic matter?
1) most solar energy is absorbed by atmosphere or reflected by clouds
2) photosynthetic pigments cannot absorb some light wavelengths
3) not all light falls directly on chlorophyll molecule
4) energy lost as heat during respiration/photosynthesis
What is the equation for net production of consumers?
N = chemical energy from ingested food (I) - (energy lost as faeces and urine (F) + respiratory losses)
N = I - (F+R)
What are 3 reasons why biomass decreases along a food chain?
1) energy lost in urine and faeces
2) some of the organism is not consumed
3) energy lost to surroundings as heat
What is the equation for rate of primary/secondary production?
biomass in specific area
_________________________
given time period
What are 4 farming practices used to increase efficiency of energy transfer?
1) exclusion of predators so no energy is lost to other organisms in the food web
2) artificial heating to reduce energy lost to maintain constant body temperature
3) restriction of movement
4) feeding is controlled at the optimum
What is the equation for % efficiency?
(energy converted to a useful form x 100)
________________________
total energy supplied
Why is a food chains length limited?
energy is lost at each trophic level so there’s insufficient energy to support a higher trophic level
