Organisation

• Cells

  Basic unit of life
• Tissue

  A group of similar cells that perform the same function.
• Organ


  A collection of tissues that carry out a specialized function of the body
• Organ systems

  A group of organs that work together in performing vital body functions.
• Digestive system

  Several organs that work together to digest and absorb food
• Enzymes

  Catalysts for chemical reactions in living things
• Temperature and enzyme activity

  • Increasing the temperature increases the rate of reaction.

  • The increase in kinetic energy means they can move faster and are more likely to collide and form E-S complexes.

  • Increasing the temperature above the optimum can break bonds which results in the active site changing.

  • The substrate no longer fits and the enzyme is denatured and doesn't function as a catalyst.
• PH and enzyme activity

  • All enzymes have an optimum pH value.

  • Higher or lower than this the enzyme will denature and the active site changes shape.

  • At this point the enzyme is no longer funtional.
• Catalysts

  Chemical agents that selectively speed up chemical reactions without being consumed by the reaction.
• Lock and key theory

  Theory of enzyme catalysis stating that the active site's structure is complementary to the structure of the substrate.
• RP - The effect on PH on Enzyme activity

  1) Put a drop of iodine solution into every well of a spotting tile.

  
  

  2) Place a Bunsen burner on a heat-proof mat, and a tripod and gauze over the

  Bunsen burner. Put a beaker of water on top of the tripod and heat the water until it is 35 °C. Try to keep the temperature of

  mixture sampled every 30 seconds

  the water constant throughout the experiment.

  
  

  3. Use a syringe to add 1 cm° of amylase solution and 1 cm° of a buffer solution with a pH of 5 to a boiling tube. Using test tube holders, put the tube into the beaker. Using test tube holders, put tube in the beaker of the water and wait for 5 minutes

  
  

  4. Next, use a different syringe to add 5 cm of a starch solution to the boiling tube.

  
  

  5. Immediately mix the contents of the boiling tube and start a stop clock.

  
  

  6. Use continuous sampling to record how long it takes for the amylase to break down all of the starch To do this, use a dropping pipette to take a fresh sample from the boiling tube every 30 seconds and put a drop into a well. When the iodine solution remains browny-orange, starch is no longer present.

  
  

  7. Repeat the whole experiment with buffer solutions of different pH values to see how pH affects the time taken for the starch to be broken down.

  
  

  8. Remember to control any variables each time (e.g. concentration and volume of amylase solution) to make it a fair test.
• Amylase


  Enzyme that breaks down starch into simple sugars. It is made in 3 places: salivary gland, the pancreas, and the small intestine.
• Protease

  Enzyme that breaks down proteins into amino acids. It is made in 3 places; the stomach, the pancreas and the small intestine
• Amino acids

  building blocks of proteins
• Lipase

  Enzyme that breaks down lipids into fatty acids and glycerol. It is made in two places: the pancreas and the small intestine
• Glycerol


  A three-carbon alcohol to which fatty acids are covalently bonded to make fats and oils.
• Fatty acids

  unbranched carbon chains that make up most lipids
• What are the products of digestion used for

  Used to make new carbohydrates, proteins and lipids. Some of the glucose that's made is used in respiration.
• Bile

  produced in the liver and stored in the gall bladder before it's released into the small intestine
• Bile - alkaline


  It neutralises the hydrochloric acid from the stomach.
• Bile emulsification


  breaks large drops of lipids into smaller drops which gives a much bigger surface area for the fat for the enzyme lipase to work on - which makes the digestion faster qq
• Benedict's test for sugars - RP

  1. Prepare a food sample and transfer 5cm3 to a test tube

  
  

  2. Prepare a water bath so that it's set to 75 °C.

  
  

  3. Add some Benedict's solution to the feat tube (about 10 drops) using a pipette.

  
  

  4. Place the test tube in the water bath using a teet tube holder and leave it in there for 5 minutes.

  Make sure the tube is pointing away from you.

  
  

  5. If the food sample contains a reducing sugar, the colution in the test tube will change from the normal blue colour to green, yellow or brick-red

  - it depende on how much sugar in in the food.
• Iodine solution for starch - RP

  1. Make a food sample and transfer 5cm3 of your sample to a test tube.

  
  

  2. Then add a few drops of iodine solution and gently shake the tube to mix the contents.

  
  

  3. If the sample contains starch, the colour of the solution will change from browny-orange to black or blue-black.
• Biuret test for proteins - RP

  1. Prepare a sample of your food and transfer 2 cm" of your sample to a test tube.

  2. Add 2 cm* of biuret solution to the sample and mix the contents of the tube by gently shaking it.

  3. If the food sample contains protein, the solution will change from blue to purple.

  4. If no protein is present, the solution will stay blue.
• Sudan III test for lipids - RP

  1. Prepare a sample of the food you're testing (but you don't need to filter it).

  Transfer about 5 cm® into a test tube.

  
  

  2. Use a pipette to add 3 drops of Sudan III stain solution to the test tube and gently shake the tu

  
  

  3. Sudan III stain solution stains lipids. If the sample contains lipids, the mixture will separate out two layers. The top layer will be bright red. If no lipids are present, no separate red layer will the top of the liquid.
• The heart

  A hollow, muscular organ that pumps blood throughout the body in a double circulatory system.
• The lungs


  main organs of the respiratory system, where gas exchange takes place.
• Gaseous exchange

  The process where oxygen is taken in from the air and exchanged for carbon dioxide.
• How are lungs adapted for gas exchange

  The alveoli give the lungs a really big surface area. this helps gas exchange happen easily and efficiently. they have moist, thin walls (just one cell thick) they have a lot of tiny blood vessels called capillaries.
• Right ventricle

  pumps deoxygenated blood to the lungs where gas exchange takes place
• Left ventricle

  pumps oxygenated blood to the body
• Aorta

  The large arterial trunk that carries blood from the heart to be distributed by branch arteries through the body.
• Vena cava


  a large vein carrying deoxygenated blood into the heart
• Pulmonary artery

  Carries deoxygentated blood from the heart to the lungs
• Pulmonary vein

  carries oxygenated blood from the lungs to the heart
• Coronary arteries

  blood vessels that branch from the aorta and carry oxygen-rich blood to the heart muscle
• Alveoli


  tiny sacs of lung tissue specialized for the movement of gases between air and blood. It carries out gas exchange.
• Bronchi


  two short branches located at the lower end of the trachea that carry air into the lungs.
• Trachea

  Allows air to pass to and from lungs
• Capillary network

  The combination of arterial and venous capillaries that surround the alveoli and individual cells.