energy transfers Flashcards
Describe how intensive rearing of domestic livestock increases net production
Slaughtered when young so more energy transferred to new biomass tissue
controlled diet so optimum amount of nutrients for easy absorption
Movement restricted so less heat lost from respiration
Kept warm inside so less heat loss so less energy lost to respiration
selectivley bred to increase efficiency of converting energy to new biomass .
Describe the reasons for low efficiency of energy transfer through ecosystems
Some light is reflected
Some light is not the appropriate wavelength so not absorbed
Some light misses chloroplasts
(producers in an ecosystem)
Energy lost by respiration
Energy loss by heat loss
Energy lost by faeces
Energy lost by undigested food
Excretion of urea
(consumers at any trophic level)
in ecosystems what do plants use to synthesise organic compounds
aquatic/atmospheric CO2
How do plants use sugars synthesised in plants?
most for respiratory substrates, some for new biological molecules to form the biomass of plants.
Explain how increase in named biomass can be taken as a measurement of NPP and why it is can be an appropriate measurement
Represents dry mass/mass of carbon
-Represents GPP – R
Define GPP
Chemical energy store in plant biomass per area/volume
define R
respiratory losses to the environment
define NPP
chemical energy store in biomass after respiratory losses to the environment
define net production of consumers
N = I – (F + R)
N is net production of consumers,
I is chemical energy store in ingested food,
F represents chemical energy lost to environment in faeces and urine,
R represents respiratory losses.
state appropriate gross productivity units
Unit of energy, per area, per year. E.g. KJ per m2 per year
Can be mass per area per year eg g per m2 per year
NPP = GPP - R
NPP = GPP – R (if question ever states npp or net primary productivity-> write this equation for one mark always)
AVAILABLE FOR
plant growth
plant production
other trophic levels
definition of biomass
the mass of carbon or dry mass of tissue per given area
fresh mass (wet)
living
easy to access
variable water content so unreliable
variable food ingested
dry mass ( mass of carbon)
dead
difficult to access
small sample size - may not be representative
unreliable as unethical to collect large samples
gm-2 or gm-3
situational - only valid at that moment in time STANDING CROP - MAY FLUCTUATE
calculating energy stored in biomass
the chemical energy stored in dry biomass can be estimated using calorimetry
-a sample of dry biomass is combusted within a sealed chamber
-chamber is surrounded by a water bath and the heat energy released causes a temp rise in the water
-using the known specific heat capacity of water and the volume of water and temperature rise we can calculate the energy released from the mass of burn biomass kj kg-1
