A short video showing you how to measure photosynthesis.
Have a go
WHAT YOU NEED: A dark room with a desk lamp, some pondweed, a glass of water, a ruler and a paper and pen.
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STEP 1: Put some pondweed into a glass full of water. Then set up a lamp 10 cm away from where the pondweed floats.
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The light from the lamp gives the plant the energy to start the photosynthesis reaction, turning carbon dioxide and water into glucose and oxygen. The faster the reaction, the more bubbles of oxygen are produced.
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STEP 2: Count the oxygen bubbles coming off the pondweed in one minute. Note down the number of bubbles and the distance of the lamp - 10 cm.
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STEP 3: Move the lamp to 20 cm away. Give the pondweed a few minutes to get used to the more distant light, then count the bubbles for a minute again and note down the number. Then move the lamp to 30 cm and repeat.
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STEP 4: As you move the lamp, what happens to the number of bubbles coming off the pondweed in a minute? The closer the light, the more energy is going into the plant and the faster the rate of photosynthesis.
