(Original post by iesians)
for preliminary :-
-practice the method beforehand to actually see if it will work or not
-write the independent variables which can affect the dependant variable
-state how you wil control them
-find out favourable conditions for the experiment and try to impose them in the actual experiment
-select a suitable timescale to measure the dependant variable.
(note ive written dependant variable ....in the real exam replace it with the dependant variable asked in the exam eg:- number of egg hatched , human height etc....)
then theres always a question on ethical issues and safety :-
-(if about animal) top notch veterinary services cannot be provided
- do not put too much stress or it may die
- relocate to natural environment soon after the experiment is over
- keep lab conditions hygeinic
-(if about plants) wear gloves
- careful of insect biting
- do not tamper with other plants
- try not to stamp on other plants
- plants may be poisonous
- wear gloves
-clean benches with ethanol
- flame necks of bottles to avoid air borne contamination
- possible chances of bacterial infection
- some people maybe allergic to certain chemicals used during the experiment.
......................for the 10 mark question basically write whatever you can think of , its 2 pages , fill them completely !!!!!!
- not possible to control all factors affecting dependent variable
- conditions in lab may differ from conditions in the natural environment
- (then become specific) eg :- cloud shade affecting sunlight reaching earth , not placing the cotton wool in same place between eye stalks , not able to keep temperature constant , impossible to control genetic variations in seeds and organisms , difficulty in counting all the eggs through the microscope ....etc etc etc !!!
Hope this helps ...!