The steps

• This experiment should ideally be carried out in a darkened room so that the only light received by the plant is from the light source.
• Avoid skin and eye contact with the sodium hydrogen carbonate ion solution
• 1. remove the plunger from the syringe of the photosynthometer, allow a gentle stream of tap water into the barrel of the syringe till the barrel and plastic tube are full of water.
• 2. replace the syringe plunger and gently push water out of the plared wend of the tube till there are no air bubbles in the water of the capillary tube
• 3. cut a 7 centimeter length of well illuminated aquatic plant, make sure that there are no bubbles of gas emerging from the cut. Place the piece of the aquatic plant with its cut end upwards into a boiling tube that contains the water that the sample had been kept and add a couple drops of the hydrogencarbonate ion solution into the solution.
• 4. stand the boiling tube in a beaker of water at around 25 degrees. have cold water ready to add in case it goes above 25.
• 5. place the light source as close tot he beaker as possible. measure and record the distance between the light source and the plant.
• 6. Leave the apparatus with the capillary positioned in a way that it does not collect gas given off by the plant for about 5 to 10 minutes so that the plant can acclimatise.
• 7. position the capilliary tube over the cut end of the plant stem and after about 5 minutes, gently pull the syringe plunger and bring the oxygen bubble into the tube against the scale and read the length of the bubble.
• 8. repeat steps 6 and 7 twice more
• 9. move the light source further from the plant. measure and record the distance or measure the light intensity using a light meter. repeat steps 6 and 7