Why does darkness affect the light-independent reactions of photosynthesis?

Photosynthesis is the process by which plants and some other organisms  prepare their own food in the presence of sunlight by utilizing water and carbon dioxide.

Photosynthesis takes place in two sequential stages Light-dependent Process and light-Independent Process.

As the name suggests Light-dependent Process takes place in th presence of light and light-independent process takes place at night or in dark.

In the Light-Independent Process or the dark reaction, carbohydrates is formed from the carbon dioxide taken from the atmosphere and modified by the addition of hydrogen, the process is called carbon fixation.

Living systems cannot directly utilize light energy and require light-independent reactions that convert the ATP ( adenosine triphosphate)  into C-C bond energy that can be released by glycolysis and other metabolic processes.

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c. heat from the poles back down towards the equator.