They add nitrogen to the soul through their nodules !
pretty sure it is an ultrasound
In photosynthesis, an electron carrier of the light cycles is the nicotinamide adenine dinucleotide phosphate or NADP. This is the oxidized form, because the reduced form of this carrier has the extra H (NADPH). This is somehow related to the electron carrier called nicotinamide adenine dinucleotide or NAD (minus the phosphate).