B4 The Processes of Life

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  • Created by: emchown
  • Created on: 09-03-15 16:19
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  • B4
    • Photosynthesis
      • carbon dioxide + water = glucose + oxygen
        • (6)CO2 + (6)H2O = C6H12O6 + (6)O2
      • Three Stages
        • 1) Light energy absorbed by Chlorophyll (not used up)
          • 2) In Chlorophyll molecule, light energy rearranges atoms of CO2 and sugar to make Glucose.
            • 3) Oxygen made as a by-product. Exits plant via leaf or reused in respiration.
      • Limitations
        • Temp. - too low, it stops/ too high - enzymes stop working
        • CO2 concentration - carbon dioxide increases, so does rate of photosynthesis
        • Light intensity - the greater the light, quicker it will take place
    • Resipration
      • Energy is released through this process
        • Used for: movement, synthesising (making) larger molecules, active transport.
      • Aerobic
        • Releases energy through breakdown of glucose molecules.
          • Combines them with oxygen molecules
        • Glucose + Oxygen = Carbon Dioxide + Water + (Energy)
          • C6H1206 + (6)O2 = (6)CO2 + (6)H20
      • Anaerobic
        • Animal Cells and some Bacteria
          • Glucose = Lactic Acid + (Energy)
        • Plant Cells and some Microorganisms
          • Glucose = Ethanol + Carbon Dioxide + (Energy)
          • eg Yeast - using in brewing and making bread.
        • Happens when oxygen supply is low (eg running)
        • Aerobic releases more energy than anaerobic. Anaerobic can only last for a shirt period of time in for humans
    • Enzymes
      • Organic Catalysts
        • Protien molecules that speed up the rate of a reaction.
      • Coded for by instructions in genes
      • Lock and Key Model
        • Only molecule with correct shape can fit into enzyme.
        • Once enzyme and molecule link, reaction takes place.
        • Products are released and enzyme is free to be reused.
      • Temperature and PH
        • To work at optimum, enzymes need constant/ specific temp.
          • Diff. enzyme = Diff. opyimum working temp.
        • Ones in human body work best at 37 degrees.
          • Below - rate of reaction slows
          • Above 40 degrees - stops working (denatures)
            • Denaturing
              • Permanent change of enzymes shape.
              • Active site becomes a diff. shape and subtrate no longer fits.
                • Active Site
                  • Place where substrate fits to enzyme.
                  • Each enzyme has specific active site - only certain substrates fit.
                  • High temp. = shape of active site changed irreversibly
                    • Molecule no longer fits and reaction stops.
                  • pH
                    • Changes in pH break Intra- and Intermolecular bonds in enzyme.
                    • Changes shape and effectiveness and active site.
              • Active Site
                • Place where substrate fits to enzyme.
                • Each enzyme has specific active site - only certain substrates fit.
                • High temp. = shape of active site changed irreversibly
                  • Molecule no longer fits and reaction stops.
                • pH
                  • Changes in pH break Intra- and Intermolecular bonds in enzyme.
                  • Changes shape and effectiveness and active site.
        • Have optimum pH.
          • Amylase (enzyme that breaks down starch in mouth) works best at pH 6.8
          • Pepsin (breaks down protien in stomach) works best at 1.5.
      • Speed up Catabolic (molecules broken down) and Anabolic (molecules built up) reactions
    • Glucose in Plants
      • Used to build other molecules
        • eg Cellulose - structural carb. makes cells walls in plants
          • Repeating molecules of a certain form of glucose.
      • Proteins made from amino acids which are made from glucose
        • Vital for growth and repair
      • Chlorophyll - organic pigment where first stages of photosynthesis take place.
      • Carbon skeleton
        • Used to build other molecules
          • eg Cellulose - structural carb. makes cells walls in plants
            • Repeating molecules of a certain form of glucose.
      • Storing Glucose
        • Converted into another carb. suitable for storage, Starch.
          • Long chain of glucose units that can be packed together efficiently.
        • Long chain of glucose units that can be packed together efficiently.
    • Plant Transport
      • Plants need other chemicals in addition to glucose
      • Roots take up minerals from soil in a solution. Nitrogen is absorbed and used by plant cells to make proteins
      • Diffusion
        • This is how substances move through cells
        • It is the overall movement of a substance from a region where is in high concentration to an area of low.
        • Does not need an energy input - its a passive process
        • Its the main method by which gases enter and leave the plant
        • Gases such as carbon dioxide and oxygen exchange between leaf and air through small hole underneath the leaf called Stomata
      • Osmosis
        • A specific type of diffusion
        • The overall movement of water from a dilute to a more concentrated solution
          • Through a partially permable membrane.
        • Allows water molecules through but not solute molecules
          • Through a partially permable membrane.
        • Gradually dilute concentrated solution
        • Happens at root hair cells - water moves from soil into cells by osmosis due to concentration gradient
      • Active Transport
        • Overall movement of a chemical substance against a concentration gradient
        • Requires energy - provided respiration
        • Found in plant roots - nitrates inside plants bigger than outside, cells use active transport to bring it from soil (low concentration) to root cell (high)
    • Fieldwork
      • Variety of of techniques to meaure the amount of avalible light and the affect on growth
      • Light meter can measure the amount of light hitting a leaf (lux).
      • Data loggers to take readings over a long period of time
      • Sample a proportion of available land using Quadrats
        • Placed randomly and plants in the area are counted.
      • Vital to use a key to ensure that plants are correctly identified.
      • Measure changes in plant life along a straight line using a transect
        • Qudrat placed at set intervals along a line and plants counted in each
    • Applications of anaerobic respiration
      • Making Bread
        • Yeast added to dough (source of glucose)
        • Dough provides anaerobic environment for year cells to grow and multiply
        • As they grow, they respire anaerobically, producing Ethanol and Carbon Dioxide
        • Bubbles of CO2 released are trapped by Gluten, making the dough expand and the ethanol evapourates
        • Once dough risen and baked, expanded structure of bread is left
      • Brewing Alcohol
        • 1) Aerobic fermentation - yeast is exposed to air and grows on sugar provided
        • 2) Some alcohol produced, but most energy used to produce more yeast cells
        • 3) Anaerobic fermentation - Takes place in absence od oxygen
        • 4) Yeast respires anaerobically and produces alcohol and CO2 instead of multiplying
        • 5) Once brewed, CO2 escapes unless brewer needs it (producing champagne)
        • 6) Longer you leave it, more alcogol produced which is poisonous to the yeast and kills it
        • To make strong alcohol, distillation has to take place
      • Biogas
        • Introduce bacteria to biodegradable substances.
        • Anaerobic digestion leads to production of methane and CO2.
        • Methane can be used as low cost fuel
        • Methane generated from materials that were thrown away, so is a renewable energy source

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