Butterflies laying their eggs on milkweed plants occurs at what level of biosphere hierarchy

This is population. - The same species is found in a similar location/environment in the biosphere. Tell me if its right?

The proton has a positive charge while the neutron has no charge they both make up the nucleus of the atom while the elections have a negative charge and surround the nucleus of the atom. the protons and electrons are used to calculate the atom's mass whereas the neutrons don't affect the mass