Bioenergetics

• Limiting Factor


  stops photosynthesis from happening any fast
• limiting factors of photosynthesis

  light

  temperature

  concentration of CO2

  chlorophyll
• disease, environmental stress or lack of nutrients can cause chloroplasts to become damaged or to not make enough chlorophyll. The rate of photosynthesis is reduced because the plant can't absorb as much light
• photosynthesis word equation

  carbon dioxide + water = glucose + oxygen
• photosynthesis location


  chloroplasts
• photosynthesis equation

  carbon dioxide + water $\rightarrow$ glucose + oxygen
• photosynthesis is an endothermic reaction in which energy is transferred from the environment to the chloroplasts by light
• limiting factors are important in the economics of enhancing conditions in greenhouses to gain the maximum rate of photosynthesis while still maintaining profit
• glucose produced in photosynthesis may be

  • used in respiration
  • converted into insoluble starch for storage
  • used to produce fat or oil for storage
  • used to produce cellulose to strengthen cell wall
  • used to produce amino acids for proteinsynthesis
• use of nitrate ions absorbed from the soil

  to produce proteins
• cellular respiration

  exothermic reaction

  continuously occurring in living cells
• the energy transferred in respiration provides all the energy needed for living processes
• aerobic respiration

  the transfer of energy using oxygen
• anaerobic respiration

  the transfer of energy without the use of oxygen
• organisms need energy for

  • chemical reactions to build larger molecules
  • movement
  • keeping warm
• aerobic respiration equation

  glucose + oxygen $\rightarrow$ carbon dioxide + water
• anaerobic respiration in muscles

  glucose $\rightarrow$ lactic acid
• anaerobic respiration in plants and yeast

  glucose $\rightarrow$ ethanol + carbon dioxide
• much less energy is transferred in anaerobic respiration than in aerobic respiration because of the incomplete oxidation of glucose
• fermentation

  • anaerobic respiration in yeast cells
  • has economic importance in the manufacture of bread and alcohol
• response to exercise

  • heart rate, breathing rate and breath volume increase to supply the muscles with more oxygenated blood
  • anaerobic respiration occurs because of insufficient oxygen
  • incomplete oxidation of glucose creates a build up of lactic acid and creates an oxygen debt
  • during vigorous activity muscles fatigue and stop contracting efficiently
• oxygen debt

  the amount of extra oxygen the body needs after exercise to react with accumulated lactic acid and remove it from the cells
• blood flowing through the muscles transports the lactic acid to the liver where is is transported back into glucose
• metabolism

  the sum of all the reactions in a cell or the body
• the energy transferred by respiration is used for the continual enzyme controlled processes of metabolism that synthesise new molecules
• metabolism includes:

  • conversion of glucose to starch, glycogen and cellulose
  • formation of lipid molecules from a glycerol molecule and 3 fatty acid molecules
  • the use of glucose and nitrate ions to form amino acids which are used to synthesise proteins
  • respiration
  • breakdown of excess proteins to form urea for excretion