Biology paper 2

• Electron transport chain

  Hydrogen atoms released from reduced NAD/FAD as they're oxidised to NAD/FAD

  H atoms split into H+ (protons) and e- (electrons)
• Photosynthesis equation

  6CO2 + 6H2O ------> C6H12O6 + 6O2
• Respiration eq


  C6H12O6 + 6O2 --→ 6CO2 + 6H20 + Energy
• ATP

  ADP phosphorylated via condensation reaction - catalysed by ATP synthase

  Energy stores as chemical energy in phosphate bond

  Hydrolysis of ATP releases energy
• ATP properties

  1. stores or releases only a small, manageable amount of energy at a time -> no energy lost as heat

  2. small, soluble molecule so it can be easily transported around the cell

  3. easily broken down, energy can be released quickly

  4. can be quickly remade

  5. ATP can't pass out of the cell so cell always has an immediate supply of energy
• Photoionisation

  Light energy 'excites' electrons - giving them more energy and causing them to be released.

  The release of electrons causes the atom or molecule to become a positively-charged ion.
• Coenzyme

  Aids the function of an enzyme - transfers chemical group from one molecule to another

  Photosynthesis:

  NADP - transfers hydrogen, can reduce (give H to) / oxidise (take H from) a molecule

  Respiration:

  NAD + FAD - transfers hydrogen

  Coenzyme A - transfers acetate
• Where does the light dependent reaction occur?

  thylakoid membrane
• Where does the light independent reaction occur?

  stroma of the chloroplast
• What happens to the neurotransmitter after it binds to receptors on the postsynaptic membrane ?

  Neurotransmitter broken down by enzymes, products recycled in presynaptic neurone

  So response doesn't keep occurring/new action potential keeps triggering
• Calvin cycle order of products

  RuBP (5C) --> CO2 (1C) --> GP x2 (3C) --> TP x2 (3C) --> glucose and other organic products
• Calvin cycle organic products

  Carbohydrates

  Lipids

  Amino acids
• How many times does the Calvin cycle need to turn to make one glucose molecule?

  6

  (5/6 TP used to regenerate RuBP)
• Photosynthetic pigments in chloroplasts


  Chlorophyll a

  Chlorophyll b

  Carotene
• Limiting factors in photosynthesis

  CO2 concentration

  Temperature

  Light intensity
• Mobile phase


  Where molecules can move

  TLC = liquid solvent
• Stationary phase


  Where molecules can't move

  TLC = chromatography paper/TLC plate
• Glycolysis

  Makes Pyruvate from glucose

  Glucose (6C) --> 2x Pyruvate (3C)

  Net gain 2x ATP + 2 reduced NAD

  Anaerobic

  Occurs in cytoplasm
• Alcoholic fermentation (anaerobic respiration)

  Glucose --> 2x Pyruvate --> 2x Ethanol + 2x CO2 + 2x ATP

  
• Lactate fermentation (anaerobic respiration)

  Glucose --> 2x Pyruvate --> 2x Lactate + 2x ATP

  
• Link reaction

  Converts pyruvate to acetyl-CoA

  Pyruvate (3C) --> Acetate (2C) --> Acetyl-CoA (2C)

  CO2 lost

  NAD --> reduced NAD

  CoA added

  Takes place in matrix of mitochondria

  Occurs twice for every glucose molecule

  
• Krebs cycle

  Produces reduced coenzymes and ATP

  Acetyl-CoA --> 6C (citrate) --> 5C --> 4C

  2x CO2 removed

  1x ATP made

  3x NAD reduced

  1x FAD reduced

  Takes place in matrix of mitochondria

  Occurs twice for every glucose molecule
• How many ATP can be made from one glucose molecule


  32
• Chemiosmosis

  A process for synthesizing ATP using the energy of an electrochemical gradient and the ATP synthase enzyme.

  Movement of hydrogen ions across a biological membrane generates ATP

  
• Oxidative phosphorylation

  Produces ATP

  (using energy from reduced coenzymes)

  Reduced FAD + NAD used as electron carriers

  Electron transport chain + chemiosmosis

  ATP synthase (electrochemical gradient)
• Producers


  Organisms that make their own food (autotrophs)
• Heterotroph

  organism that obtains energy from the foods it consumes (consumer)
• Biomass

  Chemical energy stored in a plant
• How to measure biomass

  Dry mass (mass of carbon, kg m^2)

  Calorimeter (energy released used to heat known vol of water - change in temp calculates chemical energy)
• Gross Primary Production (GPP)

  Total amount of chemical energy converted from light energy by plants, in a given area
• Net Primary Production (NPP)

  GPP-R

  (R = Respiration)

  Energy available to plant for growth and reproduction
• Primary productivity

  Primary production expressed as a rate

  Total amount of chemical energy in a given area, in a given time

  kJ ha^-1 year^-1
• Net production (secondary production/productivity)

  N = I - (F + R)

  
  

  N - Net production

  I - Chemical energy in ingested food

  F - Chemical energy lost in faeces and urine

  R - Energy lost through respiration
• Simplifying food webs reduces energy loss to other organisms

  1. Insecticides/herbicides (chemical)

  2. Parasites/pathogenic bacteria + viruses (biological)

  3. Integrated systems that use both chemical + biological methods, reduces pest no.s more, NPP increased more
• Reducing respiratory losses means energy is transferred more efficiently

  1. Movement restricted: kept in pens, movement increases rate of respiration

  2. Pens indoors + kept warm, less energy wasted by generating body heat
• Increasing net production and efficiency of energy transfer advantages

  More food produced in shorter time frame

  Food produced at lower cost
• Increasing net production and efficiency of energy transfer disadvantages


  Ethical issues : cause pain/stress/restricts natural behaviour
• Saprobionts


  Organisms that digest their food externally (enzymes) and then absorb the products
• Mycorrhizae

  Fungi form symbiotic relationship with roots of plants

  1. Increase SA of root system : help absorb ions that are usually scarce (e.g. phosphorus)

  2. Increase uptake of water by plants

  3. Fungi obtain organic compounds (e.g. glucose) from the plant
• What is nitrogen used for

  Make proteins + nucleic acids (DNA/RNA)