Topic 5 : Energy transfers

• What is photosynthesis?

  A reaction using light energy to produce glucose
• What are the reactants required for photosynthesis?

  Water and carbon dioxide
• What are the products of photosynthesis?

  Glucose and oxygen
• What are the two stages of photosynthesis?

  • Light dependent stage
  • Light independent stage
• What factors determine the rate of photosynthesis?

  Carbon dioxide concentration, light intensity, temperature
• Where does photosynthesis occur in plants?

  In chloroplasts
• How are chloroplasts adapted for photosynthesis?

  • Stacks of thylakoid membranes (grana)
  • Specific arrangement of chlorophyll
  • ATP synthase channels in granal membrane
  • Contain DNA and ribosomes

  
• What are grana in chloroplasts?

  Stacks of thylakoid membranes

  
• What is photoionisation in photosynthesis?

  Excitation of electrons in chlorophyll by light
• What is photolysis?

  Splitting of water with light
• How many photons are required to split one molecule of water?

  Four photons
• What happens to the oxygen produced during photolysis?

  It diffuses out or is used in respiration
• What is the role of protons in the light dependent reaction?

  They create a proton gradient for ATP synthesis
• What is the final product of the light dependent reaction?

  Reduced NADP
• What are the main phases of the light independent reaction (Calvin Cycle)?

  1. Carbon dioxide fixation
  2. Reduction phase
  3. Regeneration of RuBP
  4. Organic molecule production
• What is the role of Rubisco in the Calvin Cycle?

  It fixes carbon dioxide with RuBP
• What is produced during the reduction phase of the Calvin Cycle?

  Two molecules of triose phosphate
• How many turns of the Calvin Cycle are needed to produce one glucose molecule?

  Six turns
• What is aerobic respiration?

  Splitting a substrate to release carbon dioxide
• What is anaerobic respiration?

  Respiration occurring without oxygen
• What are the steps in respiration?

  1. Glycolysis
  2. Link Reaction
  3. Krebs Cycle
  4. Oxidative Phosphorylation

  
• Where does glycolysis occur?

  In the cytoplasm
• What are the products of glycolysis from one glucose molecule?

  2 pyruvate, 2 ATP, 2 NADH
• What happens to pyruvate in anaerobic respiration?

  It is converted into lactate
• What is produced during the link reaction?

  Acetyl coenzyme A
• What occurs in the Krebs Cycle?

  Acetyl coenzyme A combines with a 4-carbon molecule

  
• How many times does the Krebs Cycle turn per glucose molecule?

  Two times
• What is oxidative phosphorylation?

  Process of ATP production using electron transport

  
• What is the final electron acceptor in oxidative phosphorylation?

  Oxygen
• What is an ecosystem?

  • Community of organisms
  • Non-living elements of the environment
• What factors control the distribution of organisms in a habitat?

  Biotic and abiotic factors
• What are autotrophs?

  Organisms that produce their own food
• What are heterotrophs?

  Organisms that cannot synthesize their own food
• What percentage of energy is passed on in food chains?

  About 10%
• What are the ways energy is lost in food chains?

  • Uneaten parts
  • Decay of dead material
  • Excretion
  • Exothermic reactions
• What is the formula for calculating energy transfer efficiency?

  Percentage efficiency = (Energy transferred / Energy input) x 100
• How is biomass measured?

  In mass of carbon or dry mass of tissue
• What is net primary productivity (NPP)?

  Rate of energy transferred into new plant biomass
• What is gross primary productivity (GPP)?

  Rate of energy incorporated into organic molecules
• What is the relationship between NPP and GPP?

  NPP = GPP - R