<span>By combining it with its wild respective realtive to avoid acquiring diseases. or It can save a crop plant by altering its structure, so it can repel diseases</span>
It depends if you're talking about Physical Science or Physics/Biology -- so, I'll give both definitions (:
Physical Science: the positively charged central core of an atom, consisting of protons and neutrons and containing nearly all its mass.
Physics/Biology: a dense organelle present in most eukaryotic cells, typically a single rounded structure bounded by a double membrane, containing the genetic material.
Hope that helped! (:
I believe the answer is photosynthesis