respiration

• cellular respiration is...

  • an exothermic reaction which continuously occurs in all living cells
• what do organisms need energy for?

  • chemical reactions to build larger molecules
  • movement
  • keeping warm
• respiration can take place...

  • anaerobically [without oxygen]
  • aerobically [with oxygen]
• what is the word equation for aerobic respiration?

  • glucose + oxygen --> carbon dioxide + water
• what is the symbol equation for aerobic respiration?

  • $C_6H_{12}O_6\ +$$\ O_2\rightarrow\ CO_2+$$\ H_2O$
• what is the word equation for anaerobic respiration in muscles?

  • glucose --> lactic acid
• why does aerobic respiration release more energy?

  • the glucose molecule is fully oxidised
• why does anaerobic respiration release less energy?

  • the oxidation of glucose is incomplete
• what is the word equation for anaerobic respiration in plant and yeast cells?

  • glucose --> ethanol + carbon dioxide
• what is anaerobic respiration in yeast cells called?

  • this is called fermentation
• what are some uses of fermentation?

  • the production of alcoholic drinks like beer, the alcohol in these drinks is called ethanol
  • making bread, the carbon dioxide produced causes the bread to rise
• why do we need a lot of energy during exercise?

  • for muscle contraction
• what does the human body do during exercise?

  • reacts to the increased demand for energy
• what increases during exercise?

  • the heart rate, breathing rate and breath volume increase to supply the muscles with more oxygenated blood
• if there is not enough oxygen to aerobically respire...

  • anaerobic respiration takes place in the muscles
• what happens during anaerobic respiration in the muscles?

  • due to the incomplete oxidation of glucose, lactic acid builds up and creates an oxygen debt
• what happens during long periods of vigorous activity?

  • the lactic acid causes the muscles to become fatigued
  • so they stop contracting efficiently
• what is oxygen debt?

  • amount of extra oxygen the body needs after exercise to react with the accumulated lactic acid and remove it from the cells
• how is lactic acid converted back to glucose?

  • blood flowing through the muscles transports the lactic acid to the liver where it is then converted back into glucose
• why do people breathe heavily and rapidly after exercise?

  • to replenish the oxygen debt
• what is metabolism?

  • the sum of all the reactions in a cell or the body
• what is glucose converted into in humans?

  • glycogen - storage form of glucose
• what is lipid synthesis?

  • 1 glycerol molecule + 3 fatty acid molecules = lipids
  • found in the cell membrane
• why is protein broken down into urea?

  • humans do not need to eat a lot of protein so only the excess is broken down into urea
• why does the breathing rate increase when running?

  • to get more oxygen into the blood
  • for releasing energy for muscle contraction