It is the conversion of these photons from light energy into heat, and the tissue's reaction to this heat that produces the ultimate biologic effect.
(It; is; the conversion of these photons from light energy into heat, and the tissue's reaction to this heat) (this heat; produces; the ultimate biologic effect)
It this heat
is produces
the conversion of these photons from light energy into heat, and the tissue's reaction to this heat
the ultimate biologic effect