3.5.3 Energy and Ecosystems Flashcards
What is GPP?
Gross Primary Productivity: The rate at which chemical energy is incorporated into organic molecules by an ecosystem
What is NPP?
Net Primary Productivity: The rate at which chemical energy is incorporated into organic molecules that make up the new plant biomass
What is primary productivity?
The rate at which energy is incorporated into organic molecules
What is secondary productivity?
The amount of energy from the organism that passes on to it’s consumers or decomposers
State the equation that links NPP/GPP/R (respiration)
NPP= GPP-R
Define efficiency in relation to food chains
Energy available after transfer/energy available before transfer) x 100
Why isn’t the transfer of energy from producers to primary consumers very efficient ?
Not all of the available food is eaten (roots, bones twigs),some undigested food remains in faeces (cellulose in cell walls), much of the food absorbed by the consumers is used in respiration
What is net productivity?
The energy that is used for biomass and is available to the next trophic level
What is gross productivity ?
the available energy that is taken in
What don’t plants take in all of the available energy?
some light energy is reflected, transmitted through the leaf, is the wrong wavelength or hits parts of the plant that cannot photosynthesis (bark of a tree)
What is a primary consumer?
Organisms that eats plant material
What is a secondary consumer?
An organisms that eats primary consumers
Define ‘trophic level’
Position a species occupies in a food chain. energy is transferred from one trophic level to the next by consumers
Define detritivore
Primary consumer that feeds on dead organic material
Define decomposer
Bacteria and fungi that feed on the dead remains of organisms and animal faeces
Define biomass
The mass of an organism without water (organic material only)
Draw the nitrogen cycle
Check - ammonium - nitrites, nitrates. Denitrification, nitrification, ammonification
Define ‘denitrification’ and state why it happens
when nitrate ions in the soil are converted into nitrogen gas (by anaerobic denitrifying bacteria) - happens in waterlogged soils
Describe the process of ammonification
When organic compounds (e.g. urea) are converted into ammonia by saprobiontic microorganisms (fungi and bacteria)
Define ‘nitrification’
When ammonium is oxidised into nitrites, then nitrates by nitrifying bacteria
State two ways in which nitrogen fixation can take place
Free living nitrogen fixing bacteria can convert N2 gas into ammonia, which they use to make ammino acids. OR mutualistic nitrogen fixing bacteria in root nodules use N2 gas into amino acids whilst they obtain carbohydrates from the plants
(bit post spec)
(dont need names for AQA)
Define mycorrhizae
An association between plant roots and fungi which increase the surface area for plant roots to absorb water and minerals. The fungus receives sugars and amino acids from the plant.
Describe the process of eutrophication
Fertilisers are leached into water, algal bloom occurs on upper layers of water so light does not reach deeper water. Plants and algae at lower depths die and saprobiontic bacteria increase. As they respire, O2 concentrations decrease and aerobic organisms die. Anaerobic conditions continue and anaerobic organisms release more nitrates and toxic wastes.
Draw the phosphate cycle
