easy to get a standard quantity of plant material because each of the balls is approximately the same volume.cheap to grow and easy to make – you will be able to make hundreds in a very short time.When these algae are ‘wrapped up’ in the jelly balls they are excellent to use in experiments on photosynthesis. Sodium alginate is not harmful to the algae, and they will continue to photosynthesise once immobilised. This effectively traps large numbers of algal cells in ‘jelly like’ balls made of sodium alginate. Since algae are tiny and are difficult to work with directly in the water, the first part of the practical involves ‘immobilising’ the algae as algal balls. In this practical, students use algae to look at the rate of photosynthesis. Green algae photosynthesise in a way similar to that seen in C 3 higher plants. Please note that the algae can be purchased from other school suppliers. For post-16 students, please see our updated post-16 notes.Īlgae (Scenedesmus quadricauda) can be purchased from our recommended supplier, Darwin Biological. We suggest that a 30ml sample will need to be grown for 2-3 weeks using the growth medium recipe to ensure there is a sufficient amount for a class of 30. This page includes the core information on the protocol and the students’ notes for 11-16 students. This fun and reliable practical makes investigating photosynthesis easy, with a technique that can be used with students from KS3 to post-16, and offering quantifiable and replicable results. Photosynthesis can be a hard topic to demonstrate reliably in the lab, especially in winter.
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