Unit 3 - own revision

• Enzymes - Factors affecting activity:

  Temperature:

  • As the temperature increases so does the rate of reaction.
  • Enzymes in human body = 40 degrees
  • Below optimum temperature = less temperature - fewer collisions - slower reaction.
  • Above optimum temperature = Hydrogen bonds in enzyme break - Active site and enzymes loses its shape - No catalysis

  Concentration:

  • Increases in substrate concentration = increase in rate of collisions - increase in rate of reactions.
  • Increase in enzyme concentration = increase in rate of collisions - increase in rate of reaction.
• Practical - Light intensity impacting photosynthesis

  1. Place a 10cm piece of pondweed in a beaker fill of water

  2. Fill a measuring cyclinder with water

  3. Use a ruler to position the beaker with pondweed, 1 metre away from the light source

  4. Place a heat shield in front of the beaker

  5. Put on the lamp, allow 3 mintues for the plant to become acclimatised

  6. Start stopwatch, count and record the number of bubbles released every 3 mintues

  7. Move the lamp 10cm closer to the beaker

  8. Count and record the number of bubbles released every 3 mintues

  9. Repeat steps for all distances: 10cm, 20cm, 30cm, 40cm, 50cm, 60cm, 70cm and 80cm

  10. Repeat till you have 3 sets of results for each distance
• Practical - Investigation of how light intenstiy inpacts photosynthesis:

  Variables:

  • Indepndent - Distance from light source
  • Dependent - Number of bubbles released after 3 mintues
  • Control - Temperature
• Practical - Investigation of how light intenstiy inpacts photosynthesis:

  Hypothesis:

  As the light intensity increases, the rate of photosynthesis also increases
• Plant growth and distribution:

  Human effects on improving plant growth:

  • Optimum watering
  • Correct soil ph
  • Correct nutrients present

  Negative effects from humans:

  • Trampling
  • Picking wildflowers
  • Habitat destruction
• Plant growth and distribution:

  Soil aeration:

  • Necassary for sufficient oxygen to get to the plant and for the carbon dioxide to be removed.
  • Toxins form where there is little aeration.
• Plant growth and distribution:

  Temperature:

  • Needed for seed germination
  • Seeds need soil to be within the range of temperature for them to be able to germinate
• Practical - Impact of temperature on lipase


  1. Set up 5 water baths with the temperatures: 10, 20, 30, 40, 50 degrees

  2. Add amylase solution to each water bath

  3. Leave for 5-10 minutes to allow the amylase to be at set temperature

  4. Measure 10 ml of starch solution into 5 different test tubes

  5. Label each test tube with a temperature, matching it with a watch bath

  6. Place a drop of iodine in a well of a spotting tile

  7. Measure 10 ml of amylase solution into the same test tubes containing the starch solution

  8. Place the test tubes in their water baths with the matching temperatures

  9. Start stopwatch

  10. After 1 minute, using a pipette take a sample from each test tube and add it to a well from the spotting tile

  11. Record colour

  12. Repeat experiment until there are 3 sets of results for each temperature
• Practical - Impact of temperaure on lipase:

  Hypothesis:

  • As the temperature increases, so does the rate of reaction, up till the optimum. After the rate of reaction decreases as the enzyme is denatured.
• Practical - Impact of temperaure on lipase:

  Variables:

  • Dependent - Time taken for no further colour change.
  • Independent - Temperatures
  • Control - Stopwatch
• Practical - Hydrogen peroxide:

  1. Set up 5 test tubes labelled 1 to 5.
  2. Pipette, the volumes of water and hydrogen peroxide in each of the test tubes.
  3. Mix the contents in each test tube.
  4. Use a cork borer, prepare a cylinder with potatoes with a diameter of 8mm and 40mm long.
  5. Add a drop of liquid soap to each test tube.
  6. Place the cylinder of potato in each of the test tubes.
  7. Mark the height of the liquid in each test tube using a marker pen.
  8. Start stop watch.
  9. After 5 minutes, measure the height of the bubbles that form over the contents in each test tube.
• Practical - Hydrogen Peroxide:

  Variables:

  • Independent: Concentration of hydrogen peroxide
  • Dependent: Bubbles measured in mm
  • Control: Temperature, ph of solutions, size of potato cylinders
• Practical - Hydrogen Peroxide:

  Hypothesis:

  • The substrate concentration of enzyme catalysis reaction effects how much product is made.