B4.1 Nutrient Cycles Flashcards
energy transfer efficiency for plants
plants can only transfer 1% of the sun’s energy they’re receiving into chemical stores.
half of the energy gained from photosynthesis is transferred in respiration the other half is used to increase biomass
energy transfer efficiency for animals
consumers at each trophic level convert around 10% of chemical energy from food into new biomass.
why does only 10% of the animal eaten get turned into new biomass?
This is due to: inedible parts of the prey (bones), biomass lost in urine(excretion) and faeces(egestion), energy used for respiration, thermal energy wasted due to respiration
Why do food chains not have a lot of trophic levels
Because the biomass transfer is so small, the further up the chain, the less energy is available.
You’d have to eat way more to get the same amount of energy as another species down the food chain gets
Efficiency of biomass transfer equation
biomass available after transfer/biomass available before the transfer x 100%
How is water cycled?
Evaporation->CCC(geography term)->water percolates through ground (ground flow) or can travel on the ground as surface run off into a body of water.
Plants also transpire to release water into the atmosphere.
How does Nitrogen enter the ground
proteins in plants and animals are released into ground due to decay and decomposers break them down into ammonia
excretion from animals also release ammonia into the ground
How is Nitrogen entering plants and animals
nitrifying bacteria in the soil convert ammonia to nitrates that can be absorbed by the plant
denitrifying bacteria in the soil break down ammonia to nitrogen gas that enter the atmosphere
mutualism with nirogen-fixing bacteria in some plants in the roots - nitrogen in the air + oxygen = nitrates.
animals eat the plant full of nitrogen
How is carbon released into the atmosphere
respiration
decomposition - decomposers break down organic matter and CO2 is released
Burning fossil fuels - carbon in the fuels get oxidised into carbon dioxide
How is carbon removed from the atmosphere
Photosynthesis (plants, algae, phytoplankton)
carbon is also cycled through the form of glucose.
why do CO2 levels vary
photosynthesis only occurs at day
respiration is carried out constantly
huge amounts of CO2 released due to combustion of fossil fuels
deforestation (burning of wood releases carbon)
