A combination reaction, also known as a synthesis reaction in chemistry, is when two or more substances, or reactants, combine with each other to form a new product.

Decomposition reaction is just opposite of combination reaction. Photosynthesis is a redox process where oxidation and reduction both occurs. If you look at the chemical equation however, you might consider it to be a backwards combustion reaction. The combination of heat which causes a reaction in the egg whites creates a chemical reaction. The equation for photosynthesis states that the combination of carbon dioxide, water and light energy produces a carbohydrate (glucose) and oxygen. Respiration is a decomposition reaction. The chemical formula is 6CO2 + 6H2O + light energy = C6H12O6 + 6O2. The process is known as photosynthesis because, while water and carbon dioxide are the major ingredients required to cook the food, it is light that ignites the stove, and sunlight is the most abundant light that illuminates the planet.. A photosynthetic organism using the energy of photons (photo-), makes its own food (-synthesis).The Photosystem. No, it is considered a synthesis reaction (as the term photosynthesis might imply). The chemical reaction for the completion of photosynthesis is 6CO2 + H20 + light energy --> C6H12O6 + 6O2. The reaction utilizes carbon dioxide from the atmosphere, water from the plant and light from the sun to produce glucose for the plant and oxygen for the atmosphere. Because, in respiration, glucose molecules are decomposed into simple carbon dioxide and water molecules. Photosynthesis allows plants to create glucose in order to sustain life. CO2 + H2O → (CH2O) +O2 Oxidation * During photosynthesis, water gets oxidized to oxygen (O2).