Bioenergetics

• during excersise you respire more as muscles need energy from respiration to contract and you contract them more when you excersise.
• excersise

  as you respire more cells require more oxgyen, breathing reate and breath volume increase to get more oxygen to the blood, and your heart rate increases to pump more blood to the body
• what happens during vigorous excercise when the body cant supply oxygen to the muscles quickly enough

  • aneaerobic respiration
  • this is not a good way to transfer energy from glucose as lactic acid builds up in the muscles which can be painfull
• anaeobic respiration causes an oxygen debt

  • oxygen debt is the amount of extra oxygen your body needs to react with the build up of lactic acid and remove it from your cells (O reacts with lactic acid to form CO2 and H2O)
  • this means heavy breathing continues after you stop exercise to get more oxgen to the blood which is transported to muscle cells
  • the pulse and breathing rate also stay high when there are high levels of lactic acid and CO2
• how else does the body cope with the high levels of lactic acid (after vigorous exercise)

  the blood that enters your muscles transports the lactic acid to the liver where it is converted back to glucose
• what is respiration ?

  the process of transferring energy from the breakdown of glucose- it goes on in every cell in your body continuously
• how organisms use respiration :

  • to build up larger molecules from smaller ones
  • in animals it is used to allow the muscles to contract
  • in mammals it is used to keep body temp steady in colder surroundings
• what is aerobic respiration ?

  respiration using oxygen, it is the most efficient way to transfer energy from glucose

  • happens all the time in plants and animals
  • most of the reactions in aerobic respiration happen inside mitochondria
• equations for aerobic respiration:

  C6H12O6 + 6O2 --> 6CO + 6H2O

  glucose + oxygen --> carbon dioxide + water
• what is anaerobic respiration?

  respiration without oxygen - it is the incomplete breakdown of glucose making lactic acid

  • does not transfer as much energy as the glucose is not fully oxidised
  • only usefull in emergancies (e.g. during vigorous excersise)
• equation for anaerobic respiration

  glucose --> lactic acid
• anaerobic respiration in plants also produces ethanol and in yeast it is reffered to as fermentation
• what is photosynthesis ?

  using energy to change CO2 and water into glucose and oxygen

  takes place in chloroplasts

  it is an endothermic process
• equations for photosyntheisis

  carbon dioxide + water --> glucose + oxygen

  6CO2 + 6H2O -(light)---> C6H12O6 + 6O2
• how do plants use glucose?

  • for respiration
  • making cellulose
  • making amino acids
  • stored as oils or fats
  • stored as starch
• limiting factors of photosynthesis:

  • light intensity
  • CO2 concentration
  • temperature
  • amount of chloryphll a plant has
• rate of photosynthesis : light

  • not enough light slows down photosynthesis
  • as light level is raised the rate of photosynthsis inceases steadily but only up to a certain point
  • after that point it wont make any difference
• rate of photosynthesis : CO2

  • too little CO2 slows down photosynthesis
  • a higher amount of CO2 means rate of photosynthsis will increase but only up to a certain point
• rate of photosynthesis : temperature

  • usually temp is the limiting factor as its too low- the enzymes for photosynthesis work slower at lower temperatures
  • if the plant gets too hot the enzymes required for photosynthesis will be damaged- this happens at around 45'C
• light intensity is inversely proportional to the distance (squared) from the light source, so the further away you are, the less light you receive
• if you halve the distance the light intensity will be four times greater
• what is metabolism ?

  all the chemical reactions in an organism
• catabolic reaction - breaking down complex organic compounds into simpler ones releasing energy
• anabolic reaction - building up simple substances into more complex ones using energy