Differentiate between closed stomata and open stomata

Guard cell tend to open stomata during the day where there is lot of sunlight. On the other hand close stomata at night when the sun is not present and photosynthesis is not occurring ...

Guard cells tend to open stomata during the day when there is lots of sunlight and close stomata at night when the sun is not present and photosynthesis is not occurring. They will also close stomata if the air is dry or hot, which minimizes water loss through evaporation.