3.5.3: Energy and ecosystems Flashcards
What is biomass?
The mass of carbon or dry mass of tissue per given volume
What is GPP
Gross primary production. Chemical energy store in plant biomass in a given area
What is NPP
Net primary production. Chemical energy store in plant biomass after respiratory losses to the environment.
Equation with GPP and NPP and R
NPP = GPP - R
Calculation to work out the net production of consumers
N = I - (F + R)
N is net production
I is chemical energy of ingested food
F is energy lost in faeces
R is respiratory losses
Why is some energy lost in food chains in plants? (4)
- Some of the light energy is reflected
- Some light energy may be absorbed by gases
- Some of the light energy is the wrong wavelength
- Some of the light energy doesn’t hit chlorophyll
Why is some energy lost between producer and primary consumer? (3)
- Large amount of the plant may be indigestible e.g. roots and bark
- Some energy is lost by excretion as faeces and urine
- Energy is lost in respiration and as heat to the environment
Why is some energy lost between primary consumer and secondary consumer? (4)
- Large amount of animal may be indigestible
- Not all of the animal may be eaten (bones and organs)
- Some energy is lost in excretion of urine and faeces
- Energy lost in respiration and as heat to the environment.
Equation for percentage efficiency
(energy available after transfer / energy available before transfer) x 100
How does intensive rearing of domestic livestock increase net productivity. (6)
1) restricting movement so less respiratory loss due to less muscle contraction
2) Keeping animals warm indoors to reduce heat loss from body
3) feeding on a controlled diet so a higher proportion of food is digested
4) Food source is easier to absorb reducing amount of energy lost in egestion
5) selective breeding as some species are more efficient at converting energy into new tissue mass
6) slaughtered before adulthood so more energy transferred to biomass
