Ecology - Biogas and Decay 207-210 Flashcards
what is compost and what is it used for
2 points
1) it’s decomposed organic matter, used for a natural fertiliser for crops and garden plants
2) farmers and gardeners try to provide the ideal conditions for quick decay to make compost
what is responsible for decay
2 points
1) microorganisms, like bacteria and fungi
2) detritus feeders
what are the ideal conditions for decay
4 points
1) warm temperature - increases the rate that enzymes involved in decay work, can’t be too hot or the enzymes are destroyed
2) moist environment - the organisms involved need water to carry out biological processes
3) oxygen availability - the organisms need oxygen to respire to survive (but some microorganisms are involved in anaerobic decay)
4) more decay organisms - the more the faster decay happens
what is biogas
2 points
1) mainly methane which can be burned as a fuel
2) made when microorganisms decay plant and animal waste anaerobically
how is biogas made
4 points
1) sludge from sewage works or sugar factories is used to make biogas on a large scale
2) it’s made in a simple fermenter called a digester or generator
3) generators need to be kept at constant temperatures to keep microorganisms respiring
4) biogas can’t be stored as a liquid so needs to be used straight away
what are the main types of biogas generators
2 points
1) batch generator
2) continuous generator
what is a batch generator
3 points
1) makes biogas in small batches
2) they’re manually loaded up with waste, which is left to digest
3) the by-products are cleared away at the end of each session
what is a continuous generator
2 points
1) it makes biogas all the time
2) waste is continuously fed in and biogas is produced at a steady rate
what does a biogas generator need
3 points
1) an inlet for waste material
2) an outlet for the digested material to be removed
3) an outlet so the biogas can be piped to where it’s needed
how can you investigate how temperature affects the rate of decay
2 points
1) by observing the action if the enzyme lipase on a sample of milk that’s been made alkaline
2) when the lipase breaks down the milk the pH decreases
what is the method to investigate how temperature affects the rate of decay
8 points
1) measure out 5cm^3 of lipase solution and add it to a test tube - label this L for lipase
2) measure out 5cm^3 of milk and add it to a different test tube, add 5 drops of phenolphthalein indicator to the milk
3) measure out 7cm^3 of sodium carbonate solution and add it to the tube containing milk - this makes the solution alkaline and turn pink
4) but both tubes into a water bath set to 30°C and leave them until they reach this temperature - using a thermometer to check it
5) then use a calibrated dropping pipette to put 1cm^3 of lipase solution into the milk and start the stopwatch straight away
6) stir the solution, and the enzyme will start to decompose the milk - as soon as the solution loses its pink colour stop the timer and record how long it took
7) repeat the experiment at a range of different temperatures, 3 times at each temperature to calculate a mean time for each temp
8) use your results to calculate the rate of decay by using - Rate=1000/time
