The photograph shows the pondweed Elodea canadensis. (Source: © Dorling Kindersley Ltd / Alamy Stock Photo) This plant grows in ponds and rivers throughout North America. A student read that pondweed grows fastest near the water surface. The student formed the following hypothesis: The further away from the water surface the lower the rate of photosynthesis as less light can be absorbed by the pondweed. Plan a laboratory investigation that can be carried out to find evidence to support or reject this hypothesis. Your answer should give details under the following headings. Devise a detailed method, including how you would control and monitor important variables. 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Solution: