B1.3: respiration

• Cellular respiration


  A continuously occurring chemical process which is universal and occurs in all living cells. It is exothermic and releases energy (in the form ATP) from the breakdown of organic compounds like glucose.
• Exothermic reaction


  A reaction that releases energy to its surroundings, usually in the form of light or heat
• Aerobic respiration


  A form of respiration that uses a plentiful supply of oxygen to release energy from glucose.
• The word equation for aerobic respiration is

  Glucose + oxygen -> carbon dioxide + water (+ATP)
• The balanced chemical equation for aerobic respiration is

  C6H12O6 + 6O2 -> 6CO2 + 6H2O
• Anaerobic respiration


  A form of respiration that releases energy from glucose when there is an oxygen debt.
• The word equation for anaerobic respiration is

  Glucose -> lactic acid (+ATP)
• Lactic acid


  A toxic waste product that is produced during anaerobic respiration in humans and can cause muscle fatigue
• Incomplete oxidation


  Occurs during anaerobic respiration causing a build up of lactic acid in the muscles
• Fermentation


  Anaerobic respiration in plant and yeast cells which produces ethanol and carbon dioxide
• The word equation for fermentation is

  Glucose -> ethanol + carbon dioxide (+ATP)
• Uses of fermentation


  The manufacture of bread and alcoholic drinks
• Oxygen debt


  The amount of extra oxygen the body needs after exercise to react with the accumulated lactic acid
• Effect of exercise

  Increased heart rate, breathing rate and breath volume to supply the muscles with more oxygen
• Glucose (C6H12O6)


  The main reactant of respiration that is obtained from the digestion of carbohydrates
• Oxygen (O2)


  A molecule that is essential for the complete oxidation of glucose in aerobic respiration
• Carbon dioxide (CO2)


  A waste product of respiration that is removed from cells and the body via gas exchange
• Water (H2O)


  A byproduct of respiration that is either used or removed from the body typically during exhalation or urination
• ATP molecules


  Short for adenosine triphosphate. An energy source produced following respiration and is the main source of energy in cells.
• Aerobic respiration is most efficient as it produces the most ATP molecules per process, anaerobic respiration is significantly less efficient
• Benedict's reagent


  A reagent used to test for reducing sugars that produces a different colour (blue -> brick red precipitate) based on the amount of reducing sugar present.
• Biuret reagent

  A reagent used to test for the presence of peptide bonds (protein). A colour change the blue to violet indicates he presence of peptide bonds
• Carbohydrate


  A large molecule that is synthesised from simple sugars.
• Fatty acid

  A carboxylic acid that has a long carbon chain. Fatty acids react with glycerol to make lipids.
• Iodine solution


  A solution used to test for the presence of starch. A colour change from brown to blue-black indicates a positive result.
• Lipase


  An enzyme that breaks down lipids into fatty acids and glycerol.
• Lipid


  A large molecule that is synthesised from three fatty acids and a molecule of glycerol.
• Non-reducing sugar


  A sugar which doesn't have a reducing species (an aldehyde functional group).
• Protein


  A large molecule synthesised from amino acid monomers.
• Reducing sugar


  A sugar that has a reducing end (aldehyde functional group) present. It acts as a reducing agent and is oxidised itself.
• Respiration is an exothermic reaction.
• Animals need energy for:

  • muscle contraction - to move
  • growth - building new large molecules from smaller ones (tissues e.g. muscle, skin, bone)
  • keeping body temperature steady
  • making proteins, fats and carbohydrates
• Plants need energy for:

  • making amino acids from sugars, nitrates and other nutrients
  • combining amino acids to make proteins
• Why is ATP referred to as the 'universal energy currency'?

  Because it is used by all living organisms as the primary source of energy for cellular processes.
• How many ATP molecules can be made in Aerobic respiration?

  38
• How many ATP molecules can be made in fermentation?

  2 ATP molecules.
• Equation for Anaerobic respiration in animals

  C6H12O6 -> 2C3H6O3
• Equation for Fermentation (anaerobic respiration in yeast and roots)

  C6H12O6 -> 2C2H5OH + 2CO2
• In aerobic respiration, the lactic acid builds up in the muscles causing fatigue. It is taken to the river and broken down by oxygen.
• In fermentation the ethanol builds up and can't be converted to anything else. IF levels get too high, it will start to kill off the cells.