PLANT PHYSIOLOGY
PHOTOSYNTHESIS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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only in the light
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only in the dark
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in either light or dark
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only in the presence of oxygen
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Detailed explanation-1: -Though it is called the “dark reaction", the Calvin cycle does not actually occur in the dark or during night time. This is because the process requires NADPH, which is short-lived and comes from the light-dependent reactions.
Detailed explanation-2: -Although the Calvin Cycle is not directly dependent on light, it is indirectly dependent on light since the necessary energy carriers (ATP and NADPH) are products of light-dependent reactions.
Detailed explanation-3: -When the reaction of photosynthesis does not require light energy is called as a light-independent or dark reaction. It is also called as a biosynthetic phase or Calvin cycle.
Detailed explanation-4: -Light-independent reactions – It is also called the dark reaction or Calvin cycle or C3 cycle. This reaction occurs both in the presence and absence of sunlight.
Detailed explanation-5: -Oxygen, released as a by-product, passes into the atmosphere through pores in the leaves. NADPH and ATP drive the second stage, the “dark” reactions (or Calvin cycle, discovered by Melvin Calvin), which do not require light. During this stage glucose is generated using atmospheric carbon dioxide.