Subject: Science line Answer - Carbon

Date: Tue, 12 May 1998 17:32:27 +0100

From: Science Line <scienceline@bss.org>

To: caeedac.ag@skyway.usask.ca

Hello, this is a message for Debbie Hills, who wanted to know what process in photosynthesis takes carbon dioxide from the air and puts it in the ground as a sink. This is all part of the carbon cycle, the constant circulation of the element carbon through living things and the atmosphere. When we are talking about a carbon dioxide sink, we are simply talking about the fact that plants which are photosynthesisng absorb carbon dioxide. If we look at the actual reaction of photosynthesis, we see that a green plant (which contains chlorophyll) can take water and carbon dioxide and convert this into oxygen and carbohydrates - more commonly called sugar. The glucose is either then transported around the plant to where it is needed for respiration to provde cell energy, or it can be stored. Apple trees would stopre excess sugar in the fruits, while potato plants will store excess glucose in the form of starch in the roots. So, the carbon dioxide 'sink' is more or less a resevoir for carbon respiration of carbohydrates will release water and carbon dioxide the plant may die and decompose, and the carbon will the be released the carbon in fossil fuels formed from prehistoric plants will be released when those fuels are combusted the plant may be eaten by an animal, who will the release carbon dioxide back into the air as a waste product of respiration .... and so it goes on!

Hope this answers your question!

Al

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