Energy transfers

• What is the grana made up of?

  Thylakoids
• What occurs in the thylakoids?

  Light-dependent reaction of photosynthesis
• What is contained in the inner membrane?

  Chloroplast DNA (cpDNA)
• What is located in the thylakoids?

  Photosystem I and II
• What do the photosystems contain?

  Chlorophyll-a and other photosynthetic pigments
• What is located between the grana?

  Stroma
• What happens in the stroma?

  The Calvin cycle
• What happens in the electron transport chain?

  Chlorophyll oxidises, donates electrons to stroma, and protons are pumped from the stroma into the thylakoid lumen, through the ATP synthase complex
• What happens in the light-dependent reaction?

  -Photolysis of water in PSII produces of H+ ions, free electrons and O2

  -Electrons gets excited and travels down the ETC through a series of redox reactions, losing energy each time which is used to pump H+ across the thylakoid membrane, creating a proton gradient

  - NADP binds with an electron and a proton to form NADPH

  -Proton passes through the ATP synthase which catalyses the synthesis of ATP where ADP combines with a Pi
• How much TP is regenerated to RuBP?

  83%
• Why is carbon dioxide a limiting factor in the Calvin cycle?

  Less carbon dioxide results in less GP being made, meaning less TP can be made, leading to a rise in RuBP
• Why is temperature a limiting factor in the Calvin cycle?

  Because rubisco is an enzyme with an optimum temperature, so any temperature below this will inhibit is efficacy
• Why is light intensity a limiting factor of photosynthesis?

  Light is the source of photons which are necessary for the light-dependent reaction to occur, whose products are used for the light-independent reaction
• What occurs during glycolysis?

  Glucose is phosphorylated into glucose phosphate, split into triose phosphate then oxidised to pyruvate
• What occurs during the Link reaction?

  2mol of pyruvate are decarboxylated and dehydrogenated in the mitochondrial matrix, releasing 2mol of CO2, reducing 2mol of NAD and producing Acetyl, which binds with Co enzyme A to form 2 acetyl CoA
• What occurs during the Krebs cycle?

  Acetyl-CoA breaks down, and the acteyl group binds with a 4C compound to form a six carbon compound. It is then decarboxylated and dehydrogenated twice to form a 4C compound, 2 molecules of CO2, 3 molecules of NADH and 1 molecule of ATP, where it is dehydrogenated by an isomerase enzyme to return to oxaloacetate
• What happens during oxidative phosphorylation?

  The reduced carriers NADH and FADH are oxidised

  The hydrogen splits to form an electron that travels down the ETC

  and a H+, which travels down the [H+] gradient and through the ATP synthase channel in the intermembrane space, catalysing ATP

  Oxygen acts as the final electron acceptor, combining with an electron from the ETC and a H+ from the ATP synthase channel to form water
• How can carbohydrates function as a respiratory substrate?

  Disaccharides can be hydrolysed to form monosaccharides, which can be modified by isomerase to form glucose
• How can lipids function as a respiratory substrate?

  Lipase can hydrolyse lipids, forming fatty acids and glycerol which can be used to form triose phosphate
• How can proteins function as a respiratory substrate?

  Deamination removes amino groups, making keto acids, which can turn into pyruvate, acetyl CoA or oxaloacetate depending on which R group is removed
• What happens during lactose fermentation?
• What happens during ethanol fermentation?

  pyruvate releases CO2 to form acetaldehyde and electrons from NADH are transferred to acetaldehyde to produce ethanol and NAD+
• Community

  All the populations of organisms living together in an environment
• Population


  The total number of the same species in an environment
• Ecosystem


  A community in conjunction with abiotic factors
• Abiotic factors

  Chemical, physical or non-living parts of an ecosysyem. pH, temperature, light intensity, humdity, radiation
• Net Primary Production

  The energy or biomass that remains in an ecosystem after cellular processes such as respiration
• Gross Primary Production


  The total primary production of an ecosystem
• How to calculate NPP

  NPP=GPP-R
• How can biomass be calculated?

  Calorimetry
• How to calculate NPP

  Ingested energy - (excretion + respiratory)
• Explain the nitrogen cycle

  - Nitrogen fixation: Gaseous nitrogen is fixed by nitrogen fixing bacteria (mutualistic in leguminous nodules/ free living) into nitrogenous compounds that can be used in organic compounds

  - Producers are consumed by consumers, where energy is lost at each trophic level through respiration and excretion

  - Ammonification: Both producers and consumers die, being decomposed by saprobionts which releases ammonia into the soil, producing ammonia by removal of the amine group (NH3)

  - Nitrification: Nitrifying bacteria converts ammonium ions into nitrites and nitrates under aerobic conditions, which can be actively uptaken by hair root cells in plants

  - Denitrifcation: Under anaerobic conditions, dentrifying bacteria convert nitrates into nitrogen gas during
• Explain the phosphorus cycle


  Phosphate are locked up in rocks
• Explain the process of leaching


  Rain water washes nitrate ions out of fields and into rivers
• Explain the process of eutrophication

  -Nitrate ions cause algal bloom on the surface of a lake

  -Lack of light results in aquatic plants dying > no photosynthesis

  -Saprobionts use oxygen to respire aerobically to decompose the dead plants

  -Less oxygen in water, causing aquatic organisms to die
• What occurs during the Calvin cycle?

  -Carbon dioxide reacts with RuBP, forming 2 molecules of GP, catalysed by the enzyme rubisco

  -ATP and NADPH are used to reduce GP to triose phosphate

  -Some triose phosphate is converted to useful organic substances

  -Most is regenerated to reform RuBP