ecosystems Flashcards
gross primary production
the total quantity of the chemical energy in plant biomass stored at any given area in a igiven time
why is NPP less than GPP (3 marks)
GPP is the total quantity of chemical energy stores in any given area in a given time
some of this energy gets used for respiration
which reduces the energy available for net primary production
why are trophic levels limited
relatively inefficient energy is available
because the total energy available is less at each level, as one moves up a food chain
so more trophic levels wouldnt be sufficiently supported
why is energy transfer different eg from small to big
the energy transfer from ants to small lizards is more efficient because the total mass of organisms is higher in a lower trophic level
so more energy is transferred
small lizards are larger than ants, so they use more energy for respiration and movement
so less energy is stored in biomass and more energy is wasted in small lizards than ants
biomass
total mass of living material in a specific area at a specific time
why is dry biomass used over biomass
there are different amounts of water in different tissues within an organism
dry biomass allows more accurate comparisons between different organisms
suggest the apparatus needed for drying the potato and finding the energy value of the resulting biomass
heat-proof open topped container so moisture can lead the potato sample and evaporate
oven so the potato sample is slowly dried
scale so mass of sample is recorded as it dries
calorimeter so we can calculate the chemical energy stored
explain how the chemical energy store of the potato can be calculated
bomb calorimeter is used
dried potato is burned and the resultant energy released is used to heat a known volume of water
change in temperature of water is stored and estimate chemical energy stored
feeding of weevil by hedgehog for crops
hedgehogs feed directly on weevil
so wheat productivity will increase so there would be a decrease in number of weevil
or wheat productivity would decrease because there would be an increase in the number of weeds
factory farming and energy efficiency
factory farmed poultry have a higher percentage in energy efficiency than the free-range
- movement is restricted so less energy used in muscle contraction
- so less heat less from body
- no exposure to predators
movement and growth
more movement leads to more energy lost through respiration
increased movement leads to less energy transferred to biomass
free movement leads to an increase in muscle condition and superior meat quality
increased risk of livestock being eaten by predators
quality of feed and growth
feed can optimally supply nutrients
feed promotes muscle growth
feed would be more expensive than grazing
introducing feed would be labour-intensive
