bioenergetics

• photosynthesis

  • light energy is trapped by photosynthesis as it takes in energy it is an endothermic reaction
  • takes place in the leaf (chlorophyll) absorbs light energy
• carbon dioxide + water = (light)= glucose + oxygen

  • CO2 + H2O = C6H12O6 + O2
• • increasing the light intensity, increases the rate of photosynthesis
  • increasing the level of CO2, the rate of photosynthesis increases
  • increasing temperature, enzymes involved in photosynthesis will work faster but if the temperature is too high the enzymes will denature causing the rate of photosynthesis to lower
  • lower amount of chlorophyll will cause less leaves to trap light energy, which is needed for photosynthesis
• uses of glucose from photosynthesis

  • releases energy in respiration
  • produces insoluble storage molecule called starch
  • cellulose is made from the glucose
  • for the plant to make amino acids from glucose, they need to absorb nitrate ions from the soil
• how greenhouse can affect the rate of photosynthesis

  • farmers light and heat their greenhouses and adds more carbon dioxide
  • expensive so some gardeners use oil burners as they release heat and carbon dioxide at the same time
• respiration

  the energy needed is supplied by respiration (exothermic) because it releases energy and takes place continually in all living cells
• aerobic respiration

  glucose + oxygen = energy released= carbon dioxide + water

  C6H12O6 + O2 = CO2 + H2O

  releases a great deal of energy as the glucose molecule has been fully oxidised
• Anaerobic respiration in muscles

  glucose = lactic acid and release less energy than aerobic respiration as the oxidation in glucose is incomplete
• anaerobic respiration is yeast cells and plants

  glucose = ethanol + carbon dioxide (energy also released)
• fermentation

  anaerobic respiration in yeast cells is called fermentation, used to make alcoholic drinks made by ethanol formed by fermentation
• what happens in the body during exercise

  • aerobic respiration increases as the body cells need more oxygen
  • to provide oxygen the breathing rate and volume increases and heart rate increases to pump oxygenated blood around the body
  • sometimes not enough oxygen is supplied to the muscles, causing anaerobic respiration to take place in the muscle
  • during vigorous exercise, lactic acid causes muscles to be fatigued causing the muscles to stop contracting efficiently so the body has to remove the lactic acid which creates a condition called the oxygen debt
• • aerobic respiration increases, the body cells need more oxygen
  • so the breathing rate and volume increases and heart rate increases to pump oxygenated blood around the body
  • sometimes not enough oxygen is supplied to the muscles, causing anaerobic respiration to take place in the muscle
  • during vigorous exercise, lactic acid causes muscles to be fatigued, the muscles to stop contracting efficiently so the body has to remove the lactic acid, oxygen debt
  • lactic acid is transported out of the muscles by blood which is taken to the liver and converted back to glucose by chemical reactions
• oxygen debt

  amount of extra oxygen the body needs after exercise to deal with the accumulated lactic acid
• metabolism

  the sum of the chemical reactions in a cell or the body
• glucose in plants

  • cellulose - strengthens the cell wall
  • starch - storage form of glucose
  • +nitrate ions and amino acids - used to synthesis proteins
• glucose in humans

  converted to glycogen which is a storage form of glucose
• 1 molecule of glycerol + 3 fatty acid molecules

  forms a lipid which is found in the cell membrane
• proteins

  • excess proteins are broken down into the chemical urea which is excreted by the kidneys