Bioenergetics B4

• metabolic reactions (GLURP)

  • glucose - glycogen ( a storage molecule in animal cells), starch ( a storage molecule in plant cells) and cellulose (a component of plant cell walls).
  • lipid molecules - made from 1 glycerol and 3 fatty acids
  • urea - from the excess protein and is broken down in a reaction to produce urea that is then excreted in the urine
  • respiration - glucose is broken down in respiration and transfers energy to power all the reactions in the body that make molecules
  • proteins - from amino acids from glucose and nitrate ions
• metabolism


  the sum of all the reactions that happen in the cell/body
• respiration

  the process of transferring energy from glucose which goes on in every cell
• [1] plant uses of glucose (Red Cats Are Fluffy/Old Snakes)

  • respiration - transfers energy from glucose which enables the plants to convert the rest of the glucose into various useful substances
  • making cellulose - glucose converted into cellulose for making strong plant cell walls
  • making amino acids - glucose is combines with nitrate ions absorbed from the soil to make amino acids which are then made into proteins
• [2] plant uses of glucose (Red Cats Are Fluffy/Old Snakes)

  • stored as fats or oils - glucose is turned into lipids for storing in seeds
  • stored as starch - glucose is turned into starch and stored in roots, stems and leaves ready for use when photosynthesis doesn't happen e.g. the winter
• why is starch better for storage in plants than glucose?


  starch is insoluble making it better for storing than glucose because a cell with lots of glucose would draw in lots of water and swell up
• what happens when you exercise?

  • increased respiration - muscles need energy to contract, so they contract more frequently to get more energy
  • breathing rate and breath volume increase - get more oxygen to the blood
  • heart rate increase - so that it can get the oxygenated blood around the body faster and remove CO2 quicker
  • really vigorous exercise = respiring anaerobically since the body cannot supply enough oxygen to the muscles causing build up of lactic acid
  • long periods of exercise = muscle fatigue as they get tires and stop contracting efficiently
  • red in the face and sweating
• aerobic respiration word equation


  glucose + oxygen --> carbon dioxide + water
• aerobic respiration symbol equation


  C6H12O6 + 6O2 → 6CO2 + 6H2O
• anaerobic respiration in muscle cells


  glucose --> lactic acid
• anaerobic respiration in plants and yeast cells


  glucose --> ethanol + carbon dioxide
• creating ideal condition for farming in a greenhouse

  • increase level of CO2 by using a paraffin heater to heat the greenhouse and as the paraffin burns, it makes carbon dioxide as a by-product
  • light is always needed so farmers supply artificial light after the sun goes down for more photosynthesis
  • keeping plants enclosed make it easier to keep them free from pests and diseases
  • add fertilisers in soil to provide all minerals needed for healthy growth
• how does a greenhouse work?

  • they trap the sun's heat and make sure that the temperature doesn't become limiting
  • in summer they may use shades or ventilation cool things down, whilst in the winter they may use a heater so that temperature doesn't become limiting
• factors affecting rate of photosynthesis/limiting factors

  • light intensity
  • carbon dioxide concentration/levels
  • temperature
• photosynthesis word equation


  carbon dioxide + water --> glucose + oxygen
• photosynthesis symbol equation


  6CO2 + 6H2O → C6H12O6 + 6O2