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Old 05-04-2006, 03:58 PM
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Originally Posted by sciencefreak
Certain planrs which grow near the poles under the thick layer of ice do survive in the dark. the question is how?

Marine plants need light in order to photosynthesise and grow. So what happens in an environment where there is no daylight for four months of the year, and for much of the rest of the time there is a thick covering of ice? These are the conditions faced by plants in Antarctic marine coastal waters. Nevertheless, these plants can grow well enough to help support a very rich array of benthic marine fauna (see “Assessing biodiversity”).

The amount of light that gets through the ice to the water below is a key influence on organisms living under persistent sea ice. This determines whether plants can photosynthesise, and consequently can affect the amount and type of food available for herbivores. Thus sea-ice affects both primary (plant) and secondary (animal) production.

Monotropa uniflora can actually grow in dark (and spoooooooooky) environments because it is not dependent on light for photosynthesis. You can find this plant in rich habitats-- dense moist forests with much surface leaf litter, often in a situation that is too shaded for autotrophic (photosynthetic) growth.

This is my view on this. I agree with Smarty C, that most plants (plants that you and I know) would NOT live long in dark (since they can't photosynthesize). They would use up the energy they have, and that's it for them.

However, if there is energy available, plants can grow for a while. For example, a seed sprouts no matter what, and the sprout doesn't have chlorophyll. But after being exposed to the light, the sprout begins to turn green and get chlorophyll. Without getting light, the sprout cannot live long, and would die in a sort of whitish yellow shade.

So growth isn't dependent on photosynthesis, but it is dependent on an energy source, and that usually is photosynthesis.
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