Ward's World Activity Guides

+ ward ' s science 5100 West Henrietta Road • PO Box 92912 • Rochester, New York 14692-9012 • p: 800 962-2660 • wardsci.com Find materials for this activity at wardsci.com. Discover more free activities at wardsworld.wardsci.com Make Your Own Algae Beads (continued) Equipment Set Up • Set up a ring-stand to position your separatory funnel above a 500mL beaker (or larger) on a stir-plate. Day 29 or 30—Make Your Algae Beads • Your algae should have settled to the bottom of the flask. Pour off the excess media to concentrate it. • *Mix concentrated algae and 2% Sodium Alginate solution. For every 100mL of algae culture, add 50mL of Sodium Alginate. • Pour Algae/Sodium Alginate mixture into your separatory funnel. • Stir 3% Calcium Chloride Solution well to re-suspend any particles, and fill the empty beaker. Set stir-plate to low. • Open the stopcock on the separatory funnel gradually to slowly drop the algae mixture into the Calcium Chloride mixture. • Algae will form beads as it lands in the Calcium Chloride solution. Keeping the Calcium Chloride mixing slowly will help prevent the beads from clumping together as they form. • *Allow the beads to sink to the bottom of the beaker holding the Calcium Chloride solution. The beads will float at first, however, once they sink to the bottom they are fully formed and ready for use. • Strain the beads out of Calcium Chloride solution with a tea-strainer (or with a spoon). Store them in the refrigerator in distilled water. Expected Results: Results may vary based on materials used, setup, procedure, and other factors, however, here are a few examples on what to expect: • Following this procedure will allow you to produce algae-beads that can be used for studying photosynthesis and respiration. Follow-up Teaching Notes: • If you don't have access to a separatory funnel and ring-stand, you can also drip the algae/sodium alginate mixture using plastic transfer pipettes or a syringe. • To demonstrate photosynthesis/respiration, simply place freshly rinsed algae beads into a Bicarbonate Indicator solution and observe the color change under different lighting conditions. Add Inquiry: • Do marine and freshwater algae react differently to the process? • Does algae cell shape (Euglenoid vs. Colonial, vs. Filamentous) matter to size/uniformity? • What happens to the shape of the drop as you increase/decrease the size of the drop? (can you influence this by changing the Sodium Alginate concentration?) • If you increase/decrease the concentration of Sodium Alginate used, what happens to the rate of photosynthesis you see? • How does of arrangement (surface area), number, concentration of beads affect photosynthesis/respiration rates? Disposal/Clean-up: • Pour leftover algae, or any un-used algae beads into a 10% bleach solution and allow to sit for 24 hours, then pour down the drain and rinse well. • Dispose of any un-used chemicals according to local regulations. Refer to SDS's for assistance.

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