<P> The carbon dioxide is fixed in the cytoplasm of mesophyll cells by a PEP reaction similar to that of C pathway . But, unlike the C mechanism, the resulting organic acids are stored in vacuoles for later use; that is, they are not immediately passed on to the Calvin cycle . The latter cannot operate during the night because the light reactions that provide it with ATP and NADPH cannot take place . </P> <P> During the day, the CO-storing organic acids are released from the vacuoles of the mesophyll cells and enter the stroma of the chloroplasts where an enzyme releases the CO, which then enters into the Calvin cycle . </P> <P> The most important benefit of CAM to the plant is the ability to leave most leaf stomata closed during the day . Plants employing CAM are most common in arid environments, where water comes at a premium . Being able to keep stomata closed during the hottest and driest part of the day reduces the loss of water through evapotranspiration, allowing such plants to grow in environments that would otherwise be far too dry . Plants using only C carbon fixation, for example, lose 97% of the water they uptake through the roots to transpiration - a high cost avoided by plants able to employ CAM . </P> <P> The C pathway bears resemblance to CAM; both act to concentrate CO around RuBisCO, thereby increasing its efficiency . CAM concentrates it temporally, providing CO during the day, and not at night, when respiration is the dominant reaction . C plants, in contrast, concentrate CO spatially, with a RuBisCO reaction centre in a "bundle sheath cell" being inundated with CO . Due to the inactivity required by the CAM mechanism, C carbon fixation has a greater efficiency in terms of PGA synthesis </P>

A plant that uses cam photosynthesis would most likely be found