plant physiology hormones auxins cytokinins ethylene abscisic acid gibberellins tropism positive/negative phototropism scototropism heliotropism gravitropism hydrotropism thigmotropism tendril nastic movements nyctinastic thigmonastic *not included* plant nutrition essential elements macronutrients C,H,O,P,K,N,S,Ca,Mg micronutrients Fe,Mo,B,Cu,Mn,Zn,Cl,Ni