4 atp is used
The energy source for phosphorylation in cells is often adenosine triphosphate (ATP). ATP is a molecule that stores and transfers energy within cells and is commonly used to add phosphate groups to other molecules, a process that drives many cellular reactions.
solar
The energy can come from many different sources.
the sun is the main source of energy but there are many others
The Sun.
You have to have a source of geothermal energy within reach, which not many cities have.
There are many sources of energy, Ultimately it all comes from the big bang.
energy source :)
The sun
Photosynthesis is a metabolic pathway that converts light energy into chemical energy. Its initial substrates are carbon dioxide and water; the energy source is sunlight (electromagnetic radiation); and the end-products are oxygen and (energy-containing) carbohydrates, such as sucrose, glucose or starch. This process is one of the most important biochemical pathways,[1] since nearly all life on Earth either directly or indirectly depends on it as a source of energy. It is a complex process occurring in plants, algae, as well as bacteria such as cyanobacteria. Photosynthetic organisms are also referred to as photoautotrophs
Energy is stored in the source through various mechanisms such as chemical bonds (in fossil fuels), gravitational potential energy (in hydroelectric dams), or electromagnetic fields (in batteries). When the source undergoes a process such as combustion, falling water, or chemical reactions, this stored energy is released in the form of heat, light, or kinetic energy, which can be harnessed for various purposes.
Sunlight keeps many plants alive by supporting photosynthesis process and is a major source of Vitamin D for humans.