Bioenergetics

• what type of reaction is photosynthesis

  endothermic

  Plants use light for energy, absorbed by chlorophyll
• what is the equation for photosynthesis?

  CO2 + H20 —> C6H12O6 + O2
• Light intensity

  as we increase light intensity we increase photosynthesis.

  More light means more energy which means quicker reactions.

  
• Carbon dioxide concentration

  more carbon dioxide means there is an endless amount, plants keep photosynthesising

  
• temperature

  If we increase temperature enzymes work faster increasing the rate of photosynthesis, however if we increase temperate too much enzymes will start to denature and the rate falls.

  
• uses of glucose from photosynthesis

  • release energy in respiration
  • produce insoluble storage molecule starch
  • fats and oils (store energy )
  • cellulose for cell wall
  • amino acids use nitrates to synthesise proteins
• what are the limiting factors of photosynthesis?

  • light intensity
  • temperature
  • carbon dioxide concentration
  • amount of chlorophyll
• why do farmers want to increase their rate of photosynthesis ?

  Farmers spend money on increasing limiting factors to yield as much as possible

  the price must be justified by the increase in yield
• what is respiration

  a chemical reaction that releases energy. We need energy to be alive.

  Respiration is an exothermic reaction
• aerobic respiration

  glucose + oxygen —> Co2 +h2o

  • releases a great deal of energy
  • glucose molecule is fully oxidised
• anaerobic respiration

  glucose —> lactic acid

  • releases much less energy than aerobic
  • oxidisation of glucose molecule is incomplete
• anaerobic respiration in plant and yeast cells

  glucose —> ethanol + co2

  • in yeast it’s called fermentation
  • fermentation can make alcohol and bread
• what happens during exercise?

  The need for energy is very high as muscles contract, so demand must increase. This means your lung volume and breathing rate increases so that you respire more (aerobic). We get more oxygenated blood, heart rate increases to pump it around the body.
• what happens if you can’t aerobically respire fast enough?

  not enough oxygen, anaerobic starts to take place. This leads to a build up of lactic acid, muscles become fatigued and can no longer work efficiently.

  You must remove the lactic acid = oxygen debt
• what is an oxygen debt?

  Amount of oxygen needed after exercise to remove lactic acid.

  It’s the reason heavy breathing continues after you stop exercising.
• What is metabolism?

  the sum of all the chemical reactions in a cell or body
• what happens to proteins in excess?

  They turn into urea and are excreted by kidneys.