unit B6 cont.

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  • unit B6 cont.
    • useful microorganisms
      • yogurt making
        • ALL EQUIPMENT MUST BE STERILE
          • milk is passtrised to 78oC
            • cooled down and incubated with a culture of bacteria
              • finbalyit is sampeled addied favours coulors and finally packaged
        • the Bactria used is called lactobacillus this causes the lactose to break down to lactic acid this is why the yogurt tastes acidic
      • fermentation
        • this is done under anerobic conditions
        • the word equation is glucose --->ethanol + carbon dioxide
        • first sugar is extracted from the grapes or oats
          • yeast is added
            • kept warm and all other organisms and air kept out so it can ferment proplperaly
              • bear / wine is allowed to clarify and the clear liquid ids hen filtered from the yeast sediment
                • the wine/bear can them be pasteurised or bottled
        • the amount of alcohol produced by this is limited to a certain contrition so to make it stronger you have to distillate it this can only b done with a licence
          • this needs to happen because high amounts of achole kill the yeast but some strains are more restant than others
        • the symbol equation for this proses is C6H12O2----> 2C2H5OH+2CO2
        • when yeast is respiring it soon uses up all the oxygen in the container and divides quicly the conditions then a kept anaerobic to produce alcohol
        • yeast has its own optimum conditions so will break sugar down at different rates at different conditions
        • pasteurisation is used to kill any harmful microbes the liquid is kept at a higher temperature of a set time this time depends on what is being brewed
    • life in soil
      • soil contains mineral partials of different sizes in sandy soil theses are smaller than in clay soil
      • loam soil contains a mix of clay and sand a lot of partly decomposed animal and plant waste known as humus
      • experiments on soil
        • you can find humus by burning it with a Bunsen burner
        • find air space by seeing how much water it will take to fill them
        • water content can be found by slowly heating the soil to evaporate the water
      • if soil has large particles then then air content and permeability will be higher
      • if it has larger amounts of humus it will often hold more water and air
      • living in soil
        • organisms that live in the soil depend a constraint on oxygen and water for chemical reactions
        • humus is important as it will release minerals into the soil and increases air and water content
        • earthworms are important because they
          • bury organic materials for decomposers to decompose it
          • aerate and drain soil
            • this allows organisms to respire aerobically
          • mix up soil layers
          • neutralise acidic soil
            • this slops to low PH and allows for better soil meaning plants grow better
              • mix up soil layers
          • many of these functions were first understood by Charles Darwin
    • biofules
      • this is using energy trapped in bio mass such as
        • fast growing trees are grown then they are burnt
        • waste sugars that have been fermented
          • why use biofuels positives and negatives
            • alternative to fossil fuels
            • makes no net increase to green house gasses
            • makes no particulates when burned
            • these are carbon neutral
            • could destroy habitats by planting for biofules
            • other plants wont be able to remove carbon dioxide witch could make it less carbon neutral
      • Biogas
        • contains mainly methane some carbon dioxide and other gasses e.g. hydrogen nitrogen and hydrogen sulphide
        • can be produced on a large scale in a digester uses continues flow as waste comes in gas goes out
        • used for electricity generation to make hot water and steam and as fuels for vehicles
        • production increases with temperature increase up to 45oC
          • because enzymes work best a 45oC any higher and they denature
        • if it has over 50% methane can be burned in a controlled way but at 10% it will explode
        • clean fuel but has less energy than natural gas
      • gasohol
        • petrol mixed with alcohol very cheep
        • good for places with little oil but lots of sugar
    • enzymes in action
      • many biological washing powders use these enzymes
        • amylase to digest starches
        • lipases to remove fatty stains
        • proteases to remove protein stains
        • biological washing powders work best at moderate temperatures  as these are optimum conditions
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