B1.3 RESPIRATION

• Cellular respiration is the process of transferring energy from the breakdown of glucose
• why cant the energy from respiration be used immediately by the cell?

  Energy is stored in the form of a special molecule called ATP.  

  • ATP can then be used in cellular processes where energy is required
• ways energy is used in human body

  muscle contractions

  cell division + growth

  active transport

  protein synthesis

  maintenance of a constant body temperature

  passage of nerve impulses
• 2 types of respiration

  aerobic - in the presence of oxygen

  anaerobic - in the absence of oxygen
• what is cellular respiration controlled by?

  Enzymes.
• aerobic respiration word equation

  glucose + oxygen --> carbon dioxide + water
• where does aerobic respiration take place?

  mitochondria
• TRUE OR FALSE: aerobic respiration is the complete breakdown of glucose to release a large amount of energy.

  true
• why is cellular respiration an exothermic reaction?

  it transfers energy to the environment in the form of heat
• true or false: anaerobic respiration involves the complete breakdown of glucose.

  false
• anaerobic respiration in animals

  glucose --> lactic acid
• lactic acid builds up in muscle cells and lowers the pH of the muscle tissue (making the conditions more acidic).

  • acidic conditions can denature the enzymes in cells.
• • Lactic acid will eventually be broken down using oxygento produce carbon dioxide and water as waste products
  • The amount of oxygen required to break down the lactic acid that has built up is referred to as the 'oxygen debt'
  • The process of breaking down the lactic acid is known as ‘repaying the oxygen debt’
• anaerobic respiration in plants/fungi

  glucose --> ethanol + carbon dioxide
• what is fermentation?


  anaerobic respiration in yeast
• fermentation word equation

  glucose --> alcohol + carbon dioxide
• what 3 elements do carbohydrate molecules contain?

  Carbon, hydrogen, and oxygen.
• where are carbs broken down in the human body?

  mouth and small intestine
• what is a monosaccharide?

  a simple sugar that consists of a single monomer unit for example glucose or fructose
• what is a disaccharide?

  when 2 monosaccharides join together.

  for example: maltose is formed from 2 glucose molecules. sucrose is formed from 1 glucose and 1 fructose molecule.
• what is a polysaccharide?

  formed when lots of monomer units join together in long chains to form a polymer. for example: starch, glycogen or cellulose.
• what are protein polymers made of?

  amino acids
• what is a lipids basic unit?

  one glycerol molecule + 3 fatty acid chains
• TRUE OR FALSE: the basic units in lipids form polymers.

  false
• what can lipids be divided into and when?

  fats (solid at room temp) and oils (liquids at room temp)
• which enzyme breaks down lipids?

  lipase in the small intestine
• which enzyme breaks down proteins and where?

  Protease, in the stomach and small intestine.
• what enzyme breaks down carbs?

  Amylase
• what is a reducing sugar?

  include simple sugars like glucose that are just made from one unit and some sugars made from two units like maltose.
• what test is used for reducing sugars like glucose?

  benedicts test
• • Add Benedict's reagent (which is blue) to the sample solution in a test tube
  • Heat in a water bath that has been set at 75•C for 5 minutes
  • Take the test tube out of the water bath and observe the colour
• what will a positive test show in benedicts test?

  a colour change from blue to orange/dark red.
• what do we use to test for starch in a food sample?

  iodine
• what will a positive test show in iodine test?

  orange/brown to blue/black.
• how to identify if protein is present in a sample?

  the biuret test
• • Add drops of biuret solution (a mixture of sodium hydroxide and copper sulphate) to the food sample
  • A positive test will show a colour change from blue to violet / purple
  • If there is no protein present, the solution will stay blue
• what test is used to identify lipids?

  an emulsion test
• Emulsion test steps

  • Mix the food sample with 4cm3 of ethanol and shake
  • Allow time for the sample to dissolve in the ethanol
  • Strain the ethanol solution into another test tube
  • Add the ethanol solution to an equal volume of cold distilled water (4cm3)
• the more lipid is present, the ____ the milky colour will be.

  stronger