Require practicalactivity - light intensityandphotosynthesis

• What process do plants use to make their own food?

  Photosynthesis
• Why is the food produced by plants important?

  It is essential for the plants themselves and for other organisms that feed on them
• What factors affect the rate of photosynthesis?

  • Light intensity
  • Temperature
  • Carbon dioxide concentration
• What is the formula for sodium hydrogencarbonate?

  NaHCO₃
• How does light intensity relate to distance from the light source?

  Light intensity is proportional to distance and decreases as the distance increases
• What is the aim of the experiment described in the study material?

  To investigate the effect of light intensity on the rate of photosynthesis
• What are the independent, dependent, and control variables in the experiment?

  • Independent variable: Distance from the light source/light intensity
  • Dependent variable: Number of bubbles produced per minute
  • Control variables: Concentration of sodium hydrogencarbonate solution, temperature, same piece of pondweed
• What should be done to the boiling tube before adding the pondweed?

  Allow it to stand for a few minutes and shake to disperse air bubbles
• How long should the pondweed be cut for the experiment?

  8 cm long
• What is the purpose of counting the bubbles produced by the pondweed?

  To measure the rate of photosynthesis
• How many times should the bubble count be repeated?

  Five times
• What is a potential extension activity for the experiment?

  Measuring the volume of oxygen produced using a gas syringe
• What is the effect of chlorophyll on photosynthesis?

  Only areas of the leaf with chlorophyll can photosynthesize
• What color does the iodine solution turn in areas of the leaf that had chlorophyll?

  Blue-black
• What safety precautions should be taken when using boiling ethanol?

  Ensure that no Bunsen burners are turned on as ethanol is highly flammable
• What are the steps involved in testing the effect of chlorophyll on photosynthesis using a variegated plant?

  1. Drop the leaf in boiling water to kill it
  2. Soak the leaf in hot ethanol to remove chlorophyll
  3. Dip the leaf in boiling water to soften it
  4. Spread the leaf in a Petri dish and cover with iodine solution
  5. Observe the color change
• What is the purpose of adding sodium hydrogencarbonate to the water in the experiment?

  To supply carbon dioxide, a reactant in photosynthesis
• What is the significance of using an LED bulb in the experiment?

  It does not raise the temperature of the water
• How can the effect of different wavelengths of light on photosynthesis be investigated?

  By using colored acetate filters to study blue, green, and red light
• What is the role of chlorophyll in photosynthesis?

  Chlorophyll absorbs light energy for photosynthesis
• What happens to the areas of the leaf without chlorophyll during the starch test?

  They remain pale and do not photosynthesize
• What should be done to ensure safety when handling the lamp during the experiment?

  Ensure that your hands are dry when handling the lamp
• How does the experiment measure the rate of photosynthesis?

  By counting the number of oxygen bubbles produced per minute
• What is the distance the pondweed should be placed from the light source in the experiment?

  10 cm
• Why is it important to control variables in the experiment?

  To ensure that the results are valid and reliable
• What could be a reason for varying the distance from the light source during the experiment?

  To observe how light intensity affects the rate of photosynthesis
• What conclusions can be drawn from the experiment regarding light intensity and photosynthesis?

  Higher light intensity increases the rate of photosynthesis, as indicated by more bubbles produced