Hormone PAG (Effect of Gibberellins on Hormone PAG (Effect of Gibberellins on
Growth): Growth):
Control Variables:
5mm thickness of cotton wool in each
petri dish – should cover entire base.
Temperature kept constant for all.
Preventing contamination – use only
clean equipment for each concentration
of solution.
Humidity – keep humidity of room
constant – keep a lid on the petri dish –
the same volume of solution is to be
added if the cotton gets too dry (2cm3).
Species of plant – kept constant.
Hormone used – gibberellic acid.
Number of seeds per dish – 20.
Time intervals – all checked daily at
same time.
Light intensity – LED lamp at same
distance away & same wattage for all
dishes.
Independent variable:
Concentration of gibberellic acid – 0-
100 ppm – intervals of 0ppm, 20ppm,
40ppm, 60ppm, 80ppm & 100ppm.
Dependent Variable:
Germination of mustard seeds – count
number of seeds germinated each day.
Method:
Set up 6 concentrations of gibberellic
acid solution:
0ppm = 80cm3 of distilled water.
20ppm = 64cm3 distilled water & 16cm3
gibberellic acid.3
40ppm = 48cm3 distilled water & 32cm3
Growth): Growth):
Control Variables:
5mm thickness of cotton wool in each
petri dish – should cover entire base.
Temperature kept constant for all.
Preventing contamination – use only
clean equipment for each concentration
of solution.
Humidity – keep humidity of room
constant – keep a lid on the petri dish –
the same volume of solution is to be
added if the cotton gets too dry (2cm3).
Species of plant – kept constant.
Hormone used – gibberellic acid.
Number of seeds per dish – 20.
Time intervals – all checked daily at
same time.
Light intensity – LED lamp at same
distance away & same wattage for all
dishes.
Independent variable:
Concentration of gibberellic acid – 0-
100 ppm – intervals of 0ppm, 20ppm,
40ppm, 60ppm, 80ppm & 100ppm.
Dependent Variable:
Germination of mustard seeds – count
number of seeds germinated each day.
Method:
Set up 6 concentrations of gibberellic
acid solution:
0ppm = 80cm3 of distilled water.
20ppm = 64cm3 distilled water & 16cm3
gibberellic acid.3
40ppm = 48cm3 distilled water & 32cm3
