<span>Plants take in oxygen all the time for respiration.
Photosynthesis which begins by combining water and CO2, continues in the
"dark phase" in making the glucose molecule. Light is not used for this
part of the reaction so it is called dark , because light is needed for
the first part.
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Primary succession occurs in areas without life, while secondary succession occurs in places that were previously inhabitated.
Hope this helps!
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Photosynthesising primary producers require sunlight. Therefore, in the ocean, phytoplankton would be concentrated within the surface layers of the ocean where the sunlight penetrates. Phytoplankton support a wide range of marine life: zooplankton feed on phytoplankton, which in turn support fish and so on.
