Topic Four - Bioenergetics

• What type of reaction is cellular respiration?

  Exothermic and it continuously occurs in living cells. The energy transferred supplies all the energy needed for living processes.
• What is anaerobic respiration?

  Respiration that does not use oxygen. Glucose > lactic acid. As the oxidation of glucose is incomplete in anaerobic respiration much less energy is transferred than in aerobic respiration.
• What is aerobic respiration?

  Respiration with oxygen. glucose + oxygen > carbon dioxide + water
• What do organisms need energy for?

  • chemical reactions to build larger molecules

  • movement

  • keeping warm
• How is anaerobic respiration in yeast cells represented?

  glucose > ethanol + carbon dioxide Anaerobic respiration in yeast cells is called fermentation and has economic importance in the manufacture of bread and alcoholic drinks.
• How does the body respond during exercise?

  The heart rate, breathing rate and breath volume increase during exercise to supply the muscles with more oxygenated blood.
• What happens as a result of insufficient oxygen in anaerobic respiration?

  If insufficient oxygen is supplied anaerobic respiration takes place in muscles. The incomplete oxidation of glucose causes a build up of lactic acid and creates an oxygen debt. During long periods of vigorous activity muscles become fatigued and stop contracting efficiently.
• How is lactic acid converted back to glucose?

  Blood flowing through the muscles transports the lactic acid to the liver where it is converted back into glucose
• What is the oxygen debt?


  Oxygen debt is the amount of extra oxygen the body needs after exercise to react with the accumulated lactic acid and remove it from the cells
• What is metabolism?


  Metabolism is the sum of all the reactions in a cell or the body.
• What is glucose produced in photosynthesis used for?

  • used for respiration

  • converted into insoluble starch for storage

  • used to produce fat or oil for storage

  • used to produce cellulose, which strengthens the cell wall

  • used to produce amino acids for protein synthesis.
• What does metabolism include?

  • conversion of glucose to starch, glycogen and cellulose

  • the formation of lipid molecules from a molecule of glycerol and three molecules of fatty acids

  • the use of glucose and nitrate ions to form amino acids which in turn are used to synthesise proteins

  • respiration

  • breakdown of excess proteins to form urea for excretion.
• Why are limiting factors important economically?

  Limiting factors are important in the economics of enhancing the conditions in greenhouses to gain the maximum rate of photosynthesis while still maintaining profit.
• What is the equation for photosynthesis?

  carbon dioxide + water > glucose + oxygen
• How do plants produce proteins?

  To produce proteins, plants also use nitrate ions that are absorbed from the soil, along side amino acids.
• What type of reaction is photosynthesis?

  An endothermic reaction in which energy is transferred from the environment to the chloroplasts by light.
• What is glucoses' chemical symbol?

  C6H12O6.
• How does temperature affect photosynthesis?

  usually if the temperature is the limiting factor it is because it is too low, because the enzymes work slowly at low temperature. But they also denature if the temperature is too high. This usually happens at 45 degrees.
• How does light intensity affect the rate of photosynthesis?

  not enough light slows it down. Increasing it only works up to a certain point because another factor will be the limiting one.
• How does the amount of co2 affect photosynthesis?

  too little slows it down. As long as light and co2 are in plentiful supply the factor limiting photosynthesis will be temperature.
• What is the inverse square law?


  light intensity is directly proportional to 1/distance from light squared
• How do greenhouses help grow more plants?

  keep pests out, can use heaters or shades, can control levels of co2.