CORE PRACTICALS

• What is the main focus of the practical video presented by Mr. Osman?

  Investigating the effect of pH on enzyme activity
• Which enzyme is used in the practical to investigate starch breakdown?

  Amylase
• Where is amylase produced in the human body?

  In the salivary glands and the pancreas
• What does amylase catalyze the breakdown of?

  Starch into smaller sugar molecules
• What test is used to identify the presence of starch?

  The iodine test
• What is the significance of the iodine test in this experiment?

  It shows how effective amylase is in digesting starch
• What equipment is needed to carry out the enzyme activity experiment?

  • Iodine solution and dropping bottle
  • Spotting dimple tile
  • Test tubes and test tube rack
  • Syringes and pipette
  • Amylase solution
  • Starch solution
  • Solutions of specific pH
  • Stop clock
• How do you prepare the test tube for the enzyme activity experiment?

  Measure 2 cm³ of amylase solution and add 1 cm³ of pH solution
• What should you do after adding starch solution to the test tube?

  Start the stop clock
• What indicates that starch is still present in the mixture during the experiment?

  If the iodine solution turns black
• How often should you test the solution with iodine during the experiment?

  At 10-second intervals
• What should you do if the iodine color remains unchanged?

  Note that the starch has been broken down by amylase
• How many different pH solutions should you aim to test in the experiment?

  At least four to five different pH solutions
• Why is it beneficial to repeat the experiments if time allows?

  To obtain a more accurate mean value at each pH
• What analysis tasks might the teacher guide you with after collecting data?

  • Analyzing the effect of pH on enzyme activity
  • Comparing results across different pH levels
  • Drawing conclusions based on the data obtained
• How can you use your knowledge of enzymes after completing the experiment?


  To help explain the data obtained during the experiment
• What is the aim of the experiment discussed in the video?

  To investigate the effect of temperature on the rate of aerobic respiration in small organisms
• What equipment is needed for the experiment on the rate of respiration?

  • Boiling tube containing soda lime
  • Cotton wool plug
  • Capillary tube and bung
  • Weighing boat
  • Stop clock
  • Water baths at different temperatures (e.g., 34°C, 37°C, 40°C)
  • Small organisms (maggots)
  • Two beakers
  • 4 saps millimeter scale ruler
  • Marker pen
• What is the function of soda lime in the experiment?

  To absorb carbon dioxide in the tube
• Why is cotton wool used in the boiling tube?

  To protect the user and the organisms during the experiment
• What personal protective equipment should be used during the experiment?

  Appropriate personal protective equipment
• How should the small organisms be collected for the experiment?

  Gently shake the organisms out of the container into the boiling tube
• What should be done after inserting the bung in the capillary tube?

  Set up a control tube without the organisms
• At what temperature should the tubes be placed in the water bath?

  At a preset temperature of 34°C
• Why is it best to tilt the rack slightly in the water bath?

  So that the capillary tubes hang over the side of the water bath at an angle
• How long should the organisms be allowed to adjust to the temperature?

  Five minutes
• What should be done after five minutes of adjustment time?

  Hold the beaker of colored liquid to the ends of the capillary tubes
• What should be marked after the colored liquid enters the capillary tubes?

  The position of the colored liquid in the tubes
• How long should the distance traveled by the colored liquid be timed for?

  Five minutes
• What should be done after measuring the distance traveled by the colored liquid?

  Repeat the experiment at different temperatures
• What should be consistent in each trial of the experiment?

  The same number of organisms should be used each time
• How can knowledge of aerobic respiration help in the experiment?

  It can help explain the data obtained during the experiment
• What might the teacher provide after the experiment?

  Further questions to extend understanding
• What type of small organisms are used in the experiment?

  Maggots
• What is the maximum temperature for the water bath in the experiment?

  40°C
• What should be done with the boiling tube before starting the experiment?

  It should contain soda lime granules
• Why is it important to handle soda lime with care?

  Because it is corrosive and can cause skin or eye contact
• What is the purpose of using a stop clock in the experiment?

  To time the distance traveled by the colored liquid
• What should be done with the colored liquid before measuring the distance traveled?

  It should be poured into the beakers
• Why is it important to repeat the experiment?

  To ensure accuracy and reliability of results