Nuclear fusion is a process in which a collision of two small nuclei eventually results in the formation of a single more massive nucleus with greater net binding energy and hence a release of energy. It occurs only under conditions of extremely high temperature and pressure. Nuclear fusion occurring in the cores of stars provides the energy released (as light) from those stars. The Big Bang produced matter in the form of hydrogen and smaller amounts of helium and lithium. Over time, stars (including supernova explosions) have produced and dispersed all the more massive atoms, starting from primordial low-mass elements, chiefly hydrogen.
The efficiency of the latter reaction can be determined by multiplying the efficiency of CO2; anabolism by the efficiency of hydrogen production in photosynthetic bacteria.
LabBench Activity Plant Pigments and Photosynthesis
In a broader sense, photosynthesis, including CO2 anabolism, can be divided into several steps: i) photoelectric charge isolation using photon energy (conversion to electrical energy), ii) fixation of electrical energy in the form of chemical energy (ATP synthesis), and iii) chemical reactions involving ATP (fixation of CO2, and hydrogen production).