Science at key stage 3 (Year 9)
Unit 9C: Plants and photosynthesis
Section 4: b. What is the role of the leaf in photosynthesis?
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Objectives |
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- that oxygen is produced during photosynthesis
- to decide how to measure the rate of photosynthesis
- to control variables
- to present results in tables and graphs, identifying anomalous results
- about variation between leaves
- that leaves are adapted to photosynthesise efficiently
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Activities |
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Outcomes |
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Children: |
- Extend this work by providing pupils with actively photosynthesising pondweed (Elodea) and with opportunities to discuss in groups how they could detect oxygen production. Help pupils to refine their suggestions and investigate how the release of oxygen from pondweed varies with light intensity, and to present their results as line graphs where appropriate.
- Ask pupils to suggest what happens to the oxygen produced by water plants, if necessary reminding them about organisms that respire aerobically in a pond, including pondweed and aquatic plants. Help pupils to draw up a respiration and photosynthesis cycle for a pond.
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- devise a way of measuring photosynthesis,
eg by timing the collection of a fixed volume of oxygen; by using an oxygen probe
- describe how the rate of production of oxygen varies with light intensity
- produce appropriate graphs of their results and identify and explain any anomalous results
- explain that oxygen released from photosynthesis is used by animals in respiration
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Points to note |
- Pupils will have considered respiration in animals and plants in unit 8B 'Respiration'.
- Changing oxygen concentration in water can be monitored using ICT.
Safety
- if mains voltage lamps are used as light sources for pondweed, make sure they have been tested using a portable appliance tester. Remind pupils not to splash water onto the hot bulb. Pupils' plans must be checked for health and safety before practical work begins
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This unit is divided into sections. Each section contains a sequence of
activities with related objectives and outcomes. You can view this unit by
moving through the sections or print/download the whole unit.
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