Can you think of a situation where a high temperature would not result in an increase in photosynthesis?

Nothing can photosynthesize in the night time even if the temperature goes up. But even then temperature has nothing to do with Photosynthesis.

Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that can later be released to fuel the organisms' activities.

the cell cycle is the final answer! : )