Investigating plant mineral deficiencies

Question 1

Independant variable

Answer 1

minerals present

Question 2

Dependant variable

Answer 2

physical characteristics of the plant

Question 3

Other variables to control (4)

Answer 3

• Volume of mineral solution
• Species of plant
• Size of container
• Amount of light received

Question 4

Equipment

Answer 4

• Mexican hat plantlets
• 7 test tubes
• test tube holder
• different mineral solutions:- each lacking 1 nutrient and 1 containing all
• aluminium foil

Question 5

Outline the method

Answer 5

half fill a tube with the ‘all nutrients present’ solution. Cover the top of the tube with foil or paraffin and push down on covering so that there is a well in the centre. Gently push the geranium stem/roots of Mexican hat plantlet through the hole so it is in solution below. Repeat with solutions lacking in nitrogen or phosphate or potassium or magnesium or calcium or lacking all. Wrap all tubes in aluminium foil and place in tube holder on sunny window sill. Observe regularly.

Question 6

Possible evaluation issues

Answer 6

• Ensuring accurate measurement of solutions
• No air bubble caught in xylem of geranium
• possible microorganism growth in nutrient solution
• insufficient time to see an effect.