photosynthesis

• What is the first stage of photosynthesis?

  Light dependent reaction
• Where does the light dependent reaction occur?

  Thylakoid membrane of chloroplast
• What is produced in the light dependent reaction?

  ATP and reduced NADP
• What are the components of the chloroplast's stroma?

  • Thylakoid membrane
  • Small (70S) ribosomes
  • Circular DNA
  • Starch granules / lipid droplets
  • Lamella linking grana
• What happens during photoionisation in the light-dependent reaction?

  Chlorophyll absorbs light energy, exciting electrons
• What is the result of photoionisation?

  Electrons are released from chlorophyll
• What occurs after photoionisation in the light-dependent reaction?

  1. Electrons move along the electron transfer chain
  2. Energy is used to pump protons into thylakoid
  3. Protons move into stroma via ATP synthase
  4. ATP is formed through photophosphorylation
  5. NADP becomes reduced NADP
• What is photolysis of water in the light-dependent reaction?

  Water splits into protons, electrons, and oxygen
• What enzyme catalyzes the reaction of CO₂ with RuBP in the Calvin cycle?

  Rubisco
• What are the main steps of the Calvin cycle?

  1. CO₂ reacts with RuBP
  2. Forms 2 GP molecules
  3. GP is reduced to TP using ATP and reduced NADP
  4. Some TP is converted to glucose
  5. Some TP regenerates RuBP
• How does temperature affect the rate of photosynthesis?

  Rate increases with temperature until enzymes denature
• What happens to the rate of photosynthesis as light intensity increases?

  Rate increases until another factor limits it
• How does CO₂ concentration affect the rate of photosynthesis?

  Rate increases with CO₂ concentration until limited
• What should agricultural practices aim to achieve regarding photosynthesis?

  • Increase rate of photosynthesis
  • Lead to increased yield
  • Ensure profit exceeds costs
• What is a common mistake regarding chloroplasts and light energy?

  Chlorophyll absorbs light energy, not chloroplasts
• What is the purpose of chromatography in plant pigment investigation?

  • Isolate pigments from leaves
  • Compare pigments from different plants
• What are the steps to isolate pigments using paper chromatography?

  1. Crush leaves with solvent
  2. Draw a pencil line on paper
  3. Add extract to line
  4. Stand paper in solvent
  5. Remove before solvent reaches top
• Why should the origin line in chromatography be drawn in pencil?

  Ink is soluble and would mix with pigments
• Why should the point of origin be above the solvent level?

  To prevent pigments from running off the paper
• How is the Rf value calculated?

  Distance moved by spot / distance moved by solvent front
• What is the role of dehydrogenase in photosynthesis?

  • Catalyzes reduction of NADP
  • Accepts electrons from photoionisation
• How can the rate of dehydrogenase activity be measured?

  1. Extract chloroplasts
  2. Set up test tubes with DCPIP
  3. Shine light and time color change
  4. Calculate rate from time taken
• What is the purpose of control tube A in the dehydrogenase activity experiment?

  Shows light is required for DCPIP to decolourise
• Why does DCPIP change from blue to colourless?

  DCPIP is reduced by electrons from chlorophyll
• What are the stages of aerobic respiration?

  1. Glycolysis
  2. Link reaction
  3. Krebs cycle
  4. Oxidative phosphorylation
• What are the stages of anaerobic respiration?

  1. Glycolysis
  2. NAD regeneration
• What is the net gain of ATP in glycolysis?

  2 ATP
• What happens to glucose during glycolysis?

  It is phosphorylated to glucose phosphate
• What is produced when triose phosphate is oxidized in glycolysis?

  2 pyruvate and reduced NAD
• What are the components of the mitochondria involved in respiration?

  • Outer membrane
  • Inner membrane (cristae)
  • Matrix with ribosomes and DNA
• Why is respiration important for cells?

  • Produces ATP for energy
  • Supports active transport and protein synthesis
• What does respiration produce that is essential for energy release?

  ATP
• Why is ATP important in cellular processes?

  It provides energy for active transport and protein synthesis
• What are the main components of the mitochondria involved in respiration?

  • Outer membrane
  • Cristae (inner membrane fold)
  • Matrix containing:
  • Small (70S) ribosomes
  • Circular DNA
• What are the stages of aerobic respiration?

  1. Glycolysis - cytoplasm (anaerobic)
  2. Link reaction - mitochondrial matrix
  3. Krebs cycle - mitochondrial matrix
  4. Oxidative phosphorylation - inner mitochondrial membrane
• What are the stages of anaerobic respiration?

  1. Glycolysis - cytoplasm
  2. NAD regeneration - cytoplasm
• What is the net gain of ATP from glycolysis?

  2 ATP
• What happens during glycolysis?

  1. Glucose phosphorylated to glucose phosphate using 2 ATP
  2. Hydrolysed to 2 x triose phosphate
  3. Oxidised to 2 pyruvate, producing 2 reduced NAD and regenerating 4 ATP (net gain of 2)
• What occurs after glycolysis in anaerobic respiration?

  1. Pyruvate converted to lactate (animals) or ethanol (plants)
  2. Reduced NAD is oxidised to regenerate NAD
  3. Allows glycolysis to continue, producing ATP
• Why does anaerobic respiration produce less ATP than aerobic respiration?

  Only glycolysis occurs, yielding 2 ATP