i. In bright sunlight, the Calvin cycle takes place in the stroma. At the time of the Calvin cycle, the products of the light-dependent reactants, that is, ATP and NADPH are used to transform molecules of carbon dioxide into high-energy sugars.
ii. In the darkness, the Calvin cycle also takes place in the stroma. During the Calvin cycle, the products of the light-dependent reactions, that is, ATP and NADPH are used to transform the molecules of carbon dioxide into high-energy sugars.
iii. If the plant has been kept in dark for an extended period of time, then there may be not enough production of ATP and NADPH taking place in order to continue the Calvin cycle.