Photosynthesis

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biocraz
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Photosynthesis

Post by biocraz » Sat Oct 15, 2005 6:24 pm

My taecher told me that photosynthesis consists of teo stages, light dependent stage and light independent stage. he said during the days, light energy had betransformed into chemical energy by chlorophyll and water undergoes pholysis. during the nights, the glucose is being formed and oxygen is being produced. But my question is since glucose is produced in the dark, why must we put the plants in the dark in order to destarch them? Does it means glucose is not produced during day times??

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MrMistery
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Post by MrMistery » Sat Oct 15, 2005 6:31 pm

Do you know what C3, C4 and CAM plants are? Your teacher doesn't seem to know. The two stages are temporally isolated only in CAM plants(pineapple, cactus etc) in order to prevent water loss. Only CAM plants produce glucose only at night, the rest produce it during the day, immediately after the light dependent stage.

Why do we put plants in the dark to destarch them? Well, like all organisms plants consume glucose(by first getting it from starch) by cellular respiration. In C3 and C4 plants glucose synthesis stops immediately after placing it in the dark, and degrading of starch starts. In CAM plants, at night the malic acid and aspartic acid accumulated during the day is used for glucose synthesis. But after the acids are consumed, glucose degrading starts to be obvious. Thus it will take longer to destarch them, but it will happen eventually.
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Post by biocraz » Sat Oct 15, 2005 7:19 pm

First of all, thank you for the clear explanation :) May i ask what exactly are C3 and C4 plants? What is CAM stands for?

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Post by mith » Sat Oct 15, 2005 8:30 pm

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Post by Poison » Sat Oct 15, 2005 8:51 pm

And have a search in the forum about C3 C4 and CAM
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Post by MrMistery » Sun Oct 16, 2005 4:22 pm

Searching the forum or googleing are deffinetly good ways to find about C3, C4 and CAM plants. By the way CAM comes from "Crasullacee acid methabolism", from the first plants that this strange but extremely interesting mechanism was first demonstrated
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Post by Crux » Thu Nov 10, 2005 7:17 pm

C3 and C4 plants are just categories of plants, that have diff. structures.It all depends on the way they consume CO2 into their systems. Most plants are C3. C4 plants include corn, sugar cane, and many of the summer annual plants.

You can find out the details in books or via the internet.

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