There are many chemical reactions that take place throughout the life of a plant. Every moment of a plant's life, chemical reactions are regulating energy consumption, water levels and gas exchange. While there are far too many individual chemical reactions involved in the growth of plants to list -- and many different types of plants undergo different types of chemical reactions -- there are a few major fundamental reactions that occur in all plants.
Photosynthesis is a chemical process whereby sunlight is transformed by the plant into glucose. Glucose is a carbohydrate that plants use for energy. During photosynthesis, chlorophyll converts photons, water and carbon dioxide to glucose and oxygen. The oxygen plants produce creates a breathable atmosphere for animal life.
Photosynthesis is not the only chemical reaction that produces energy in plants. Respiration is the process by which plants convert glucose and oxygen into adenosine triphosphate, or ATP, a compound used to fuel many other chemical reactions in the plant. Respiration involves four distinct chemical cycles: glycolysis, the process by which glucose is transformed to puyruvate; transition reaction or pyruvate decarboxylation, when pyruvate combines with coenzyme A to form acetyl CoA; the Krebs cycle, in which CoA is oxygenated; and the electron transport chain, which completes the production of ATP.
The activity of the plant stomata -- pore-like structures that regulate water transport, cooling and respiration -- is controlled largely by a chemical reaction involving potassium. When potassium is introduced to the guard cells around the stomata, it causes them to swell and open. When there is less water in the environment, potassium is pumped out of the guard cells and the stomata close, conserving the water inside the plant. Plants without enough potassium are less able to regulate their water levels.