TOPIC 5

• MYCHORIZZAE?

  • associations between fungi and roots of plants
  • fungi act as extensions of roots, increasing total surface area for absorption of water and minerals
  • act like sponges holding water and minerals around roots (can resist drought and take up ions more easily)
  • fungus receives organic compounds, e.g. sugars and amino acids, from plant
• WHAT IS NPP?

  • net primary production
  • chemical energy store in plant biomass
  • after respiratory losses considered
  • available for growth, reproduction or next trophic level
  • NPP = GPP - R
  • kJm^-2y^-1
• BIOMASS?

  total mass of living material in a specific area at a given time (gcm^-2 or gcm^-3)

  -> measured dry
• WHAT IS GPP?

  • gross primary production
  • total quantity of chemical energy
  • stored in plant biomass in a given area/ volume
  • GPP = NPP + R
  • kJ^-2y^-1
• NET PRODUCTION OF CONSUMERS?

  N = I - (F + R)

  N: net production of consumers

  I: chemical energy store of ingested food

  F: energy lost in faeces and urine

  R: energy lost in respiration
• HOW TO IMPROVE PRODUCTIVITY IN FARMING PRACTICES?

  1. Factory farming

  • confined spaces
  • reduce movement, less energy in muscle contraction
  • warm, reduces heat loss
  • controlled feeding (optimum type, no waste) e.g. high protein food pellets
  • exclude predators

  1. Selective breeding
  2. Genetic modification
  3. Growth hormone injections
  4. Simplifying food webs (eliminate competition)
• IMPACTS OF NITROGEN CONTAINING FERTILISERS?

  • reduced species diversity (nitrogen-rich soil favours rapidly growing species, outcompete other species, e.g. nettles and grasses)
  • leaching
  • eutrophication
• GROWING LEGUMES?

  • die and decompose
  • ammonification
  • plough breaks up plants
  • NH4+ released from nodules
  • increased nitrification
• FARMING PROCESSES?

  + ploughing

  + growing legumes

  -. harvesting plants

  -. removing livestock

  -. overwatering
• FARMING IMPACTS?

  • monocultures (destroy habitats/ food sources)
  • herbicides (lowers species richness, destroys habitats/ food sources)
  • fertilisers
  • selective breeding
• LIGHT DEPENDENT REACTION?

  1. Chlorophyll absorbs light
  2. Electrons raised to higher energy level, lost (photoionisation)
  3. Photolysis replaces lost electrons (2H2O -> O2, 4H+, 4e-), protons accumulate in thylakoid space creating a proton gradient
  4. Excited electrons passed down series of protein complexes
  5. Energy from electrons pump protons from stroma into thylakoid space
  6. Higher concentration of protons in thylakoid space than stroma, creates electrochemical proton gradient
  7. Protons move across thylakoid membrane by diffusion through ATP synthase (stalked particle), energy drives photophosphorylation (proton motive force)
  8. ATP produced from ADP and Pi (phosphorylation)
  9. Electron combines with protons to form hydrogen atom, reduces NADP
• ANAEROBIC RESPIRATION IN MAMMALS VS YEAST?

  • mammals produce lactate, yeast produce ethanol and CO2
  • both regenerate NAD
  • mammals pyruvate is reduced, in yeast pyruvate decarboxylated to ethanal then reduced to ethanol
  • both occur in low oxygen concentration
  • both produce 2 molecules of ATP
  • both occur in cytoplasm
• PRODUCTS OF EACH STAGE - FROM ONE GLUCOSE MOLECULES?

  GLYCOLYSIS

  • 2 ATP
  • 2 pyruvate
  • 2 reduced NAD

  LINK REACTION

  • 2 acetylcoenzyme A
  • 2 reduced NAD
  • 2 CO2

  KREB'S CYCLE

  • 4 CO2
  • 6 reduced NAD
  • 2 reduced FAD
  • 2 ATP

  OXIDATIVE PHOSPHORYLATION

  • ATP
  • H2O
• WHERE DOES EACH STAGE OF RESPIRATION OCCUR?

  1. Glycolysis: cytoplasm
  2. Link reaction: mitochondrial matrix
  3. Kreb's Cycle: mitochondrial matrix
  4. Oxidative phosphorylation: inner mitochondrial membrane (cristae)
• COMPOUNDS USED AS INTERMEDIATES IN KREB'S CYCLE?

  fatty acids and amino acids
• OXIDATIVE PHOSPHORYLATION?

  1. Reduced NAD/ FAD from Kreb's Cycle releases protons and electrons (oxidised) and returns to Kreb's Cycle
  2. Protons move into mitochondrial matrix and electrons enter electron transport chain
  3. Electrons passed down series of protein complexes in redox reaction
  4. Releasing energy, used to pump protons across mitochondrial matrix into the intermembrane space through ATP synthase
  5. Electrons are accepted by final electron acceptor, oxygen
  6. Combine with proton to form hydrogen atom, combines with oxygen to form water
  7. Pumping of protons through ATP synthase (stalked particle) from mitochondrial matrix to intermembrane space creates proton gradient
  8. Proton motive force provides energy to produce ATP from ADP and Pi
• ALTERNATIVE RESPIRATORY SUBSTRATES?

  LIPIDS

  • hydrolysed into glycerol and fatty acids
  • glycerol phosphorylated -> glycolysis
  • fatty acids broken down into 2C fragments -> acetylCoA -> Kreb's Cycle

  PROTEINS

  • hydrolysed into amino acids
  • amino group removed (deamination)
  • enter as pyruvate (3C) or intermediates in Kreb's Cycle (4C/ 5C)
• ENZYME TO REDUCE PYRUVATE TO LACTATE?

  lactate dehydrogenase
• TYPES OF PHOSPHORYLATION?

  SUBSTRATE-LEVEL

  • glycolysis, Kreb's Cycle
  • direct transfer of phosphate from respiratory intermediate to ADP producing ATP

  OXIDATIVE

  • electron transport chain
  • indirect linking of energy from phosphate to ADP producing ATP
  • involves energy from hydrogen atoms on NAD and FAD
• HOW DOES PYRUVATE FROM GLYCOLYSIS ENTER THE MITOCHONDRIAL MATRIX IN AEROBIC RESPIRATION?

  active transport
• WHAT ARE INORGANIC FERTILISERS?

  mined from rocks and deposits, converted into different forms and then blended to give the appropriate balance of minerals for each crop