bioenergetics

• What


  happensinphotosynthesis?1.Light energyisabsorbed2. Bychlorophyll (pigment)inchloroplastsin plant / algal cells3 . Thisenergyis used toconvertcarbon dioxideandwaterintoglucose (sugar)and oxygen (by-product)

  
• What


  typeofreactionisphotosynthesisand why?Endothermic reaction- energy transferred fromenvironmenttochloroplastbylight
• State the word and symbol equations for

  photosynthesis

  
• What does a


  limiting factor do?Restrictrate of photosynthesis(stop from increasing) if inlow levels.
• Describe and explain how


  temperatureaffectsrate of photosynthesis1. Astemperatureincreases, rateincreases(so temperature =limiting factor)● Asenzymescontrolling photosynthesisgain kinetic energy2. Above anoptimum temperature, ratedecreases● Asenzymesdenature(active site changes shape)

  
• Describe and explain how


  light intensityaffectsrate of photosynthesis1. Aslight intensityincreases, rateincreases(so light intensity = limiting factor)● As light provides energy needed for photosynthesis2. Above acertainlight intensity, ratestopsincreasing● Another factor is limiting eg. temperature / CO2

  
• Describe and explain how


  CO2 concentrationaffects rate of photosynthesis1. AsCO2 conc.increases, rate increases (so CO2 conc. = limiting factor)● As CO2 is areactant/raw materialneeded forphotosynthesis2. Above acertainCO2 conc., ratestopsincreasing● Another factor is limiting eg. temperature / light intensity

  
• How does


  chlorophyllaffect the rate of photosynthesis?Affects how muchlight energycan beabsorbed
• How can


  farmersuse theirknowledgeoflimiting factorstoincreasetheirprofits?●Remove limiting factors→gain maximum rate of photosynthesis→increase plant yield● Profit fromextra yieldmust begreater thanthecosts of providing conditions
• Describe the


  usesofglucoseproduced inphotosynthesis1. Used forrespiration→ torelease energy2.Convertedintoinsoluble starch→ forstorage3. Used to producefat / oil (lipids)→ forenergy storage4. Used to producecellulose→strengthen cell wall5. Used to produceamino acids→ forprotein synthesis● Combined withnitrate ionsfrom soil toform amino acids

  
• What is


  cellular respiration?● Aseriesofchemical reactionsthatrelease/transferenergyfromglucose● Occurscontinuouslyin all living cells●Exothermic reaction
• Describe how


  energyreleasedinrespirationis used●Chemical reactionstobuild larger molecules(eg. metabolism)●Keeping warm(birds and mammals only)●Movementeg. muscle contraction in animals
• State the word and symbol equation for

  aerobic respiration

  
• State word equations for


  anaerobic respirationinanimals,plants& yeast

  
• The process of


  aerobic respirationAerobic respiration (all cells)Reactants:Oxygen+glucose

  Oxidation of glucose:Complete

  Relative amount of energy transferred:High - lots per glucose molecule

  Products:CO2 and water
• The process of


  anaerobic respirationinanimal cellsand inplant / yeast cellsAnaerobic respiration (in plant/ yeast and animal cells)

  Reactants:Glucose only; no oxygen

  Oxidation of glucose:Incomplete

  Relative amount of energy transferred:Low - little per glucose molecule

  Products:Animal:Lactic acidPlant/yeast:Ethanol and CO2
• Explain the


  economic importanceofanaerobic respirationinyeast●Fermentation(anaerobic respiration in yeast) is used in...○Productionofbread→CO2makes dough rise○Productionofalcoholic drinks→ethanol is a type of alcohol

  
• Explain how the


  body reactstoincreasedenergydemandduring exercise●Increasedheart rate→increasedblood flow to muscles/lungs●Increasedbreathing rateandvolume→more air/oxygenenters lungs● To supplymore bloodcontainingmore oxygen(and glucose)to muscles● Formoreaerobic respirationtorelease energy/ toreduceanaerobic respiration&lactic acid build up

  
• What happens when


  musclesare supplied withinsufficient oxygen?●Anaerobic respiration→oxidation of glucoseisincomplete● Causing abuildupoflactic acidwhich causes:○Oxygen debt○ Muscles becomefatiguedandstop contractingefficiently (if activity long / vigorous)
• What is


  oxygen debt?Amount ofextraoxygenthe body needsafter exercisetoreactwithlactic acidandremoveit fromcells.

  ○ Duringrecovery heart rate/breathing rateremainhightopay backoxygen debt(help remove lactic acid).
• What is the role of the


  liverinrecoveringfromvigorous exercise?1.Bloodflowing throughmusclestransportslactic acidto theliver2. Where it isconvertedback toglucose

  
• What is


  metabolism?Sumofallchemical reactionsin acellor thebody○Metabolic rate=rate of these reactions
• How else do


  cellsuseenergytransferredbyrespiration?Tocontinuallycarry outenzyme-controlled processesofmetabolismthatsynthesise new molecules
• Give


  examplesofmetabolic reactionsSmaller → larger molecules1. Manyglucose moleculesare converted (joined together) into:●Starch(a storage molecule inplantcells)●Glycogen(a storage molecule inanimalcells)●Cellulose(a component ofplant cell walls)

  2.1 glycerol molecule+3 fatty acid molecules→a lipid molecule

  3.Glucose + nitrate ions→amino acids→ used tosynthesise proteins

  Larger → smaller molecules4.Respiration

  5.Break downofexcessproteinstoformureaforexcretion