bioenergetics

• photosynthesis

  • uses energy to change carbon dioxide and water into glucose and oxygen
  • takes place in chloroplast
  • chloroplast contains chlorophyll that absorbs light
  • energy transferred to chloroplast from environment by light
  • endothermic reaction (energy is transferred from the environment)
  • carbon dioxide + water -> glucose + oxygen
• Uses of glucose

  1. Respiration - transfers energy from glucose

  2. Plants change glucose into other substances

  3. Glucose changed into cellulose for making strong plant cell walls

  4. Glucose combined with nitrate ions to make amino acids

  5. Glucose turned into lipids for storing seeds

  6. Glucose stored as starch in roots, stems and leaves
• Nitrate ions absorbed from soil
• Amino acids make proteins
• Starch

  Insoluble, so can be stored better than glucose as cells with lots of glucose would draw back in water and swell up
• Starch can be used when photosynthesis isn't happening
• what affects rate of phtosynthesis?

  • light intensity
  • concentration of carbon dioxide
  • temperature
• how can chlorophyll affect photosynthesis?

  • can be affected by disease
  • can be affected by changes in environment
  • can cause chloroplast to become damaged so can’t absorb as much light so rate of photosynthesis is reduced
• respiration 


  process of transferring energy from glucose which goes in every cell
• is respiration exothermic or endothermic


  exothermique, transfers energy to the enviroment
• how do organisms use energy transferred by respirations?

  1. to build up larger molecules from snaller ones
  2. in animals to move about
  3. in mammals and birds to keep warm
• aerobic respiration

  • glucose+ oxygen -> carbon dioxide + water
  • respiration using oxygen
  • happens inside mitochondria
• anaerobic respiration

  • incomplete breakdown of glucose
  • glucose->lactic acic
• plant and yeast anaerobic respiration

  • can respire without oxygen
  • glucose-> ethanol+carbon dioxide
  • in yeast is called fermentation
• oxygen debt

  • amount of extra oxygen your body needs after excercise
  • during exercise, lungs heart and blood couldn’t keep up with demand for oxygen so now have to “repay” oxygen you didn’t get to ur muscles in time
• what is excess protein broken down into?

  urea
• what molecule is not formed by joining lots of glucose molecules together?

  protein