Just wondering: why the Calvin Cycle can occur in the dark, but indirectly relies on sunlight? Thank you for your explanation.

Since this is not my area of expertise, I searched Google under the key words "Calvin cycle sunlight dark" to get these possible sources:

http://www.chemistryexplained.com/Ny-Pi/Photosynthesis.html
http://answers.yahoo.com/question/index?qid=20071214102505AA6vPYj
http://en.wikipedia.org/wiki/Photosynthesis
http://72.14.253.104/search?q=cache:IsvqTEpCskIJ:www.lamission.edu/lifesciences/lecturenote/sfbio3/Photosynthesis.doc+Calvin+cycle+sunlight+dark&hl=en&ct=clnk&cd=6&gl=us&client=safari
http://www.mrs.umn.edu/~goochv/CellBio/lectures/darkrxn/darkrxn.html

In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search.

I hope this helps. Thanks for asking.

The Calvin Cycle can occur in the dark because it doesn't require direct sunlight for its molecular processes. However, it indirectly relies on sunlight because the energy and reducing power needed to drive the Calvin Cycle are initially obtained from the light-dependent reactions of photosynthesis.

The Calvin Cycle is a series of biochemical reactions that takes place within the chloroplasts of plants as part of the process of photosynthesis. It converts carbon dioxide (CO2) into glucose, a sugar molecule that fuels the growth and metabolism of plants.

To understand why the Calvin Cycle indirectly relies on sunlight, we need to look at the overall process of photosynthesis. Photosynthesis consists of two main stages: the light-dependent reactions and the light-independent reactions (Calvin Cycle).

During the light-dependent reactions, sunlight is absorbed by chlorophyll molecules in the thylakoid membranes of the chloroplasts. This energy is then used to split water molecules into oxygen (O2) and to convert light energy into chemical energy in the form of ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate). These energy-rich molecules are crucial for the Calvin Cycle.

In the dark, when there is no direct sunlight, the ATP and NADPH generated during the light-dependent reactions are available to power the Calvin Cycle. The energy from ATP and the reducing power from NADPH are used to convert carbon dioxide into glucose.

Therefore, even though the Calvin Cycle can occur in the absence of light, it indirectly relies on sunlight for the production of ATP and NADPH during the light-dependent reactions. These energy-rich molecules are crucial inputs that fuel the reactions of the Calvin Cycle, allowing carbon dioxide fixation and sugar synthesis to continue.