bioenergetics

• respiration is an enzyme controlled exothermic reaction. it occurs in all living things all the time. glucose is broken down to release energy. it is used for all living processes, eg, movement of muscles, digestion, nervous system.
• aerobic respiration occurs in the mitochondria. it releases more energy than anaerobic. glucose + oxygen = carbon dioxide + water

  (C 6 H 12 O 6 + 6 O 2 → 6 CO 2 + 6 H 2 O). all glucose is hydrolysed and any energy in each glucose molecule is released.
• anaerobic respiration (plant/yeast cells): glucose = ethanol + carbon dioxide + energy. also known as fermentation. occurs in the cytoplasm. breakdown of glucose is incomplete so much less energy is released than in aerobic respiration.
• anaerobic respiration (mammalian skeletal muscle cells): glucose = lactic acid + energy. occurs during heavy or prolonged exercise. occurs in the cytoplasm. breakdown of glucose is incomplete so much less energy is released than in aerobic respiration.
• photosynthesis is the process by which plants convert carbon dioxide and water into glucose, oxygen, and other organic molecules, using light energy. the organic molecules include lipids, oils, starch, cellulose and proteins. this is an endothermic reaction.
• process of photosynthesis:

  • carbon dioxide diffuses in through the stomata
  • during the day, mesophyll cells use up the carbon dioxide for photosynthesis
  • oxygen is made during photosynthesis by mesophyll cells
  • most diffuses out through the stomata, some is used for aerobic respiration
• plant adaptations for photosynthesis:

  • large surface area
  • thin leaves to absorb light
  • many stomata for carbon dioxide and oxygen diffusion
• limiting factors of photosynthesis and solutions:

  • light intensity - lamps 24 hours a day
  • carbon dioxide - artificially increase by 0.1%
  • temperature (enzymes) - keep at 25-30°C
  • water - constant supply/humid environment
  • chlorophyll