what is biomass?
mass of living material
how is energy transferred through food chain?
- light energy from sun
- green plants and algae use small % of light energy to make food during photosynthesis
- energy stored in substances that make up plant cells works it way through chain as animals eat plants and each other
- respiration supplies energy for life processes but most loast as heat to surroundings
- some waste is inedible so doesn’t pass onto next stage - end of food chain
what is each stage of the food chain called?
trophic level
what is the formula for efficiency of energy transfer?
energy available to next level/ energy available from previous level x 100
what is stable community?
when materials are taken out of soil are balanced by those put back in
describe carbon cycle
- CO2 from air is removed by photosynthesis of plants and algae which is used to make carbon compounds
- some is returned to atmosphere when respire
- plants eaten by animals and animals also respire
- when plants, algae, animals die, detritus feeders and microorganisms feed on them and decay releasing CO2
- waste from mammals go into soil and taken upby plants as nutrients
- some plants product and fuels are burnt releasing CO2
what are the four stages of the nitrogen cycle?
- nitrogen fixation
- decomposition
- nitrification
- denitrification
what happens in nitrogen fixation?
nitrogen fixing bacteria convert nitrogen from air into nitrates
lightning also converts this as it has high amount of energy
what happens in decomposition
when plants and animals decompose, the proteins and urea are converted into ammonium compounds
what happens in nitrification?
nitrifying bacteria convert ammonium compounds into nitrites and other bacteria convert into nitrates
what happens in denitrification?
denitrifying bacteria convert nitrates intro nitrogen via anaerobic respiration
