Why might the alternative pathways of photosynthesis using c4 or cam systems be described as metabolic compromises? both pathways increase the rate of photosynthesis but also increase the rate of water loss. both pathways minimize photorespiration but also expend more atp during carbon fixation. the cam pathway allows more co2 into the plant but also increases the rate of water loss. the c4 pathway decreases water loss but also increases the rate of photorespiration?