B6 d-h

B6 d-h

1. d

   • Biomass can provide energy by burning fast growing trees.
   • Biomass can provide energy via fermentation.
   • Biofuels are alternatives to fossil fuels, which do not produce particulates or add to greenhouse gas levels.
   • Biogas contains mainly methane, some carbon dioxide, and traces of hydrogen, nitrogen and hydrogen sulphide.
   • Biogas containing more than 50% methane is burnable, but below 10% methane it is explosive.
   • Biogas is a ‘cleaner’ fuel than petrol and diesel but contains less energy than natural gas.
   • Biogas can be used to provide electricity, hot water and steam for heating or to fuel cars.
   • Gasahol is a mixture of petrol and alcohol used in cars in countries like Brazil.

2. e

   • Loam is a soil with a mixture of sand and clay.
   • Humus is mostly decomposed dead material in soil.
   • When humus decomposes it releases minerals into the soil, and aerates the soil.
   • Most life in soil needs a supply of air and water.
   • Earthworms bury organic material, which is decomposed by bacteria and fungi.
   • Earthworms aerate and drain soil with their burrows.
   • Earthworms mix up layers of soil.
   • Earthworms neutralise acidic soil.
   • Charles Darwin recognised the importance of earthworms in agriculture.

3. f

   • There are four major advantages of living in water:  No shortage of water/risk of dehydration.  Less temperature variation.  Support of the body.  Easy to dispose of waste.
   • There are two disadvantages to living in water: Regulating water content and resistance to movement.
   • Light, temperature and mineral content of water all vary with seasons and depth of the water.
   • Some food chains in oceans start with bacteria, not plants, and some rely on ‘marine snow’
   • Phytoplankton are microscopic plants.
   • Zooplankton are microscopic animals.
   • Sewage and fertiliser run off can cause eutrophication
   • Biological indicators are species which are only able to survive in particular levels of oxygen or at particular pHs.

4. g

   • Biological washing powders contain carbohydrases to digest carbohydrate stains, proteases to digest protein stains, and lipases to digest fatty stains.
   • Biological washing powders work best at about 40ºC.
   • Sucrose sugar can be broken down by the enzyme sucrose into the smaller, sweeter, sugars glucose and galactose.
   • Using sweeter sugars than sucrose, means less sugar has to be added to foods.
   • Immobilising enzymes means fixing them into an insoluble material so they are easier to handle and use.
   • Immobilised enzymes do not contaminate the substance they are added to.
   • Immobilised enzymes can be used in a continuous process
   • Lactose intolerant people do not produce the enzyme lactase, so are unable to digest lactose sugar from milk.
   • Bacteria in the gut of lactose intolerant people ferment the lactose, causing wind and diarrhoea

5. h

   • New organisms produced by genetic engineering are called transgenic
   • Genes do the produce the same proteins, no matter which organism they are put in to.
   • Restriction enzymes cut DNA to leave ‘sticky ends’.
   • Ligase enzymes are used to stick other genes to the ‘sticky ends’ of cut DNA.
   • Bacteria can be genetically engineered to produce human insulin for diabetics
   • Transgenic organisms can be cloned to produce identical copies, and large quantities of the useful product
   • Bacteria contain loops of DNA called plasmids.
   • Assaying techniques are techniques used to identify if the new gene has been successfully transferred.
   • Assaying techniques are techniques used to identify if the new gene has been successfully transferred.
   • Electrophoresis is a technique used to separate pieces of DNA.
   • Radioactive probes are used to show up the DNA during DNA ‘fingerprinting’.