practical

• What plants can be used to investigate the effect of light intensity on photosynthesis?

  Cabomba or Elodea
• What do the plants release as a product of photosynthesis?

  Oxygen
• Why is an LED bulb preferred for the experiment?

  It does not raise the temperature of water
• What is the formula for sodium hydrogencarbonate?

  NaHCO3
• How does light intensity change with distance from the lamp?

  It decreases as distance increases
• What is the independent variable in the experiment?

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

  Number of bubbles produced per minute
• What are the control variables in the experiment?

  Concentration of sodium hydrogencarbonate, temperature, and pondweed
• What should be done to ensure safety when using water near electrical equipment?

  Keep hands dry when handling the lamp
• What is the aim of the experiment?

  • Investigate the effect of light intensity
  • Measure the rate of photosynthesis
• How should the pondweed be prepared for the experiment?

  Cut an 8 cm piece of Cabomba
• How long should the boiling tube stand before counting bubbles?

  Five minutes
• How should the average number of bubbles be calculated?

  Count bubbles over one minute and average
• What extension activity can measure the volume of oxygen produced?

  Collect gas in a gas syringe
• What equipment can measure changes in oxygen concentration?

  Data logging equipment
• How can different wavelengths of light be investigated?

  Use colored acetate filters
• How does chlorophyll affect photosynthesis in variegated plants?

  • Only areas with chlorophyll photosynthesize
  • Test positive for starch
  • Starch is built from glucose produced
• What is the first step in investigating the effect of chlorophyll?

  Drop the leaf in boiling water
• Why is the leaf placed in hot ethanol?

  To remove the chlorophyll
• What happens to the areas of the leaf without chlorophyll when tested with iodine?

  They remain pale
• What safety precautions should be taken when using boiling ethanol?

  No Bunsen burners should be on