2.67 understand the origin of carbon dioxide and oxygen as waste products of metabolism and their loss from the stomata of a leaf

During photosynthesis, plants use light energy (from the sun) to combine carbon dioxide and water. This produces glucose and oxygen. The plant can use glucose (in respiration) but cannot use oxygen, therefore, oxygen is a waste product.

During respiration, plants use oxygen and produce carbon dioxide (this time, the oxygen is useful and carbon dioxide is a waste product.

Gases diffuse in and out of a leaf via the stomata when they are open (during daytime/light/when photosynthesis is occurring)...