Required practical

• What is the aim of the microscopy practical?

  • To observe plant and animal cells
  • Using a light microscope
• What is the first step in the microscopy practical method?

  Add a drop of water to a slide
• What should you do after placing the onion epidermis on the slide?

  Add a drop of iodine solution
• What is the independent variable in the microscopy practical?

  Type of cell
• What is the dependent variable in the microscopy practical?

  Structures observed
• What are the key skills developed in the microscopy practical?

  Using a microscope and estimating cell size
• What is the aim of the osmosis in plant tissue practical?

  • Investigate the effect of sugar concentration
  • Measure potato mass changes
• What is the first step in the osmosis practical method?

  Cut potato cylinders of the same size
• What is the independent variable in the osmosis practical?

  Sugar concentration
• What is the dependent variable in the osmosis practical?

  Change in mass
• What happens to potato mass when water enters the cells?

  Mass increases
• What is the key concept of osmosis in plant tissue?

  Water moves depending on solute concentration
• How do you calculate the percentage change in mass in the osmosis practical?

  Use the formula: (change/original) x 100
• What is the aim of the food tests practical?

  • Test for carbohydrates, proteins, and lipids
  • Identify nutrients in food samples
• What reagent is used to test for starch?

  Iodine solution
• What color change indicates a positive result for starch?

  Brown-orange to blue-black
• What reagent is used to test for sugars?

  Benedict’s solution
• What color change indicates a positive result for sugars?

  Blue to brick red
• What reagent is used to test for proteins?

  Biuret solution
• What color change indicates a positive result for proteins?

  Blue to purple
• What reagent is used to test for lipids?

  Ethanol
• What indicates a positive result for lipids?

  Milky-white emulsion
• What is the aim of the effect of pH on amylase activity practical?

  • Investigate how pH affects amylase
  • Measure starch breakdown time
• What is the first step in the amylase practical method?

  Add amylase, buffer, and starch to a test tube
• What is the independent variable in the amylase practical?

  pH
• What is the dependent variable in the amylase practical?

  Time for starch to break down
• What is the optimum pH for amylase activity?

  Usually pH 7
• What happens to enzyme activity at extreme pH levels?

  It drops due to denaturation
• What is the aim of the photosynthesis practical?

  • Investigate light intensity effects
  • Measure rate of photosynthesis
• What is the first step in the photosynthesis practical method?

  Place Canadian pondweed in water
• What is the independent variable in the photosynthesis practical?

  Distance from light source
• What is the dependent variable in the photosynthesis practical?

  Number of bubbles
• How does light intensity affect the rate of photosynthesis?

  Closer light source increases rate
• What is the inverse square law in relation to light intensity?

  Light intensity is inversely proportional to distance squared
• What is the aim of the reaction time practical?

  • Investigate factors affecting human reaction time
  • Measure distance caught of a dropped ruler
• What is the first step in the reaction time practical method?

  One person holds a ruler vertically
• What is the independent variable in the reaction time practical?

  Condition (e.g. caffeine)
• What is the dependent variable in the reaction time practical?

  Distance caught
• How can the reaction time practical be improved?

  Use a computer-based test for precision
• What is the aim of the culturing microorganisms practical?

  • Investigate effect of antibiotics or antiseptics
  • Measure bacterial growth inhibition