Photosynthesis uses the thermal energy from sunlight to react carbon dioxide with water to produce simple sugar (glucose) and molecular oxygen (O2). The plant then metabolizes the sugar into ATP to power other cellular activity.
This is the energy route, the O2 is that of the above photosynthesis reaction. The 4 H+ and the 4 e- are those used in the half reaction (implicit in the above Photosinthesys reaction):
Photo-synthesis is the “green engine of life”. Photons, the sunlight energy from the Sun are transformed by Nature into sugars called carbohydrates = food energy. Without this magical process we would have no food or clean air. Today, with 410 ppm of CO2, plants and trees are our best hope to survive.
Photosynthesis is a process in which plants convert sunlight energy into fuel for their bodies. Therefore, light from the sun is helping the plant photosynthesise. However: artificial light can be used to grow plants as well. In that case, the energy would originate in the light source.
Photons are the only source of energy for photosynthesis. Photons are absorbed by chlorophyll molecules within Photosystems I and II (and antennae complexes), generating higher-energy ‘excited’ states of the photosystems which can carry out energetically costly chemical reactions.
Light energy from photons is converted into chemical energy in photosynthesis. The energy of photons is used to split water molecules which releases energetic electrons. Energy from the electrons drive the production of molecules of ATP and NADPH.
The sun's photons only start the reaction by exciting an electron on a molecule of Chlorophyll in a process called photo-excitation. The thing that is actual source of energy (i.e. it moves everything that is involved in Photosynthesis) is trivial.
An electron in the chlorophyll molecules becomes excited as a result of a higher level of energy. The excited electron becomes unstable and is released. Another electron is released following the capture of another photon of light by the light harvesting complex and the transfer of energy to the reaction center.
The first step of cellular respiration happens with what’s called Glycolysis. This is where a glucose molecule is broken down through various steps to a molecule called pyruvate. And because glucose is a 6 Carbon sugar and pyruvate is a 3 Carbon sugar, for every 1 glucose used, 2 pyruvates are produces. Anot.
The first stage of photosynthesis is the light dependent reactions. These reactions take place on the thylakoid membrane inside the chloroplast. During this stage light energy is converted to ATP (chemical energy) and NADPH (reducing power). Light-dependent Reactions.
In order to get enough NADPH to form one glucose (sugar) molecule, we need six water molecules. We also needed three carbon dioxide molecules to form one PGAL, and two PGALs to form one glucose, for a total of six carbon dioxide molecules to form one glucose. And six oxygens are released through this process.