Equipment
- 3% sodium alginate solution
- Algal culture
- Hydrogen carbonate indicator solution
- 50cm3 syringe
- Retort stand and clamp
- Red and blue filters
- Concentrate your active algal culture, by leaving 50cm3 to settle for 30 minutes in a measuring cylinder until you have a darker green sediment. Carefully pour off the pale green suspension to leave just 5cm3 of concentrated culture
- Mix 5cm3 of algal culture with 5cm3 of 3% sodium alginate solution in a very small beaker with a cocktail stick
- Clamp a syringe barrel above a beaker of calcium chloride solution making sure the tip of the syringe is well above the solution in the beaker
- Pour the alginate mixture through the syringe so it drips through and forms beads in the beaker. Swirl the beaker gently as the drops fall. If the solution is too thick dilute with a little more algal suspension. If it is running through too quickly, mix in more alginate
- Allow the beads to harden for a few minutes before straining them out of the beaker through a strainer
- Rinse the beads in distilled water
Method to investigate photosynthesis
- Get 3 translucent bottles
- Add an equal number of algal balls to each container;30
- Added 5cm3 of indicator to each container
- Replace the lid
- Surround each vial with a different coloured light filters and have one without a filter
- After 3 days note the colours of the vials and compare this to the indicator spectrum
- Record results
Results
If photosynthesis is at a rate that is greater then the respiration rate more O2 will be produced than CO2, this will make the solution more alkaline and therefore turn more purple. The container with the red filter is the one which turned the darkest purple which would suggest that the wavelength of red light is optimum for photosynthesis. The container with the blue filter turned yellow which means that the respiration rate exceeded photosynthesis rate. This wavelength of light does not provide the right amount of energy for photosynthesis therefore the rate decreases below the rate of respiration.