Independent: Minerals present
Dependent: Physical characteristics of plant
Control: Volume mineral solution Species plant Size container Amount light received
Method: Half fill 7 tubes each w/ ‘all nutrients present’ solution, & solutions lacking in nitrogen/phosphate/potassium/ magnesium/calcium/lacking all. Cover top tube w/ foil/paraffin & push down on covering so that there's well in centre. Gently push radish seeds through hole so it is in solution below. Wrap all tubes in aluminium foil & place in tube holder on sunny window sill. Observe regularly.
Evaluation issues: Ensure accurate measurement solutions Possible microorganism growth in nutrient solution Insufficient time to see effect
Outcome: All nutrients present: Grow healthy Lack nitrogen: Old leaves turn yellow & die, growth stunted Lack phosphate: Dark green leaves with purple veins & growth stunted Lack potassium: Yellow scorching leaves & stunted growth Lack magnesium: Yellow areas develop on old leaves & growth slows down. Lack calcium: Grow points die back & young leaves yellow & crinkly Lack all: Does not grow at all.