Why do farmers consider photorespiration to be a major problem, and how do some plants resolve this issue? On hot sunny days O, is more easily bound/fixed into the Calvin Cycle by RUBISCO instead of CO.. This generates mildly toxic intermediates and requires large amounts of ATP for disposal, and this wastes water. C3 plants have developed pathways to capture and concentrate CO, into the Calvin Cycle. O On hot sunny days Oz is more easily bound/fixed into the Citric Acid Cycle by pyruvate dehydrogenase. This generates large amounts of ATP but also wastes water. C4 plants have developed pathways to capture and concentrate O, into the Citric Acid Cycle. On hot sunny days co, is more easily bound/fixed into the Calvin Cycle by RUBISCO instead of O2. This generates mildly toxic intermediates and requires large amounts of NADPH to disposal, and this wastes CO.. C4 plants have developed pathways to capture and concentrate CO, into the Calvin Cycle. O On hot sunny days Oz is more easily bound/fixed into the Calvin Cycle by RUBISCO instead of CO. This generates mildly toxic intermediates and requires large amounts of ATP for disposal, and this wastes water. C4 plants have developed pathways to capture and concentrate CO, into the Calvin Cycle.