Anions are taken in against their electrochemical gradient
via symports, which expend the energy of the proton gradient
generated by ATPases. Cations are taken up passively by ion channels;
however the maintenance of a favourable electrochemical gradient for
cations also relies on pumping out protons.
First one is iron (or possibly magnesium) deficiency (interveinal
chlorosis on young leaves). Second one is nitrogen deficiency
(chlorosis of old leaves).