Salaam, 1st of all, do u study in a skool? If yes, hw does ur school get u prepared for this paper?
u want to know the health and safety precautions, ethical issues, and details of how to make the results more reliable for each and every prac? well....do u have the Edexcel A2 biology revision guide??
There are details of each and every core practical in it so do get one - it is available on the student forum itself in a post by stylish...it is like : Books for A level - phy, chem, bio...it is in the first link....
According to my knowledge:-
Health and saftey precautions depend on the core prac. For example in the AS beetroot core prac., we have to use a mounted needle ryt? so we have to mind our fingers. Also, in the AS strength of fibres core prac, u have to be careful from falling weights. It depends on the structure of the core prac.
You only have to know ethical issues related to the brine shrimp and habituation core prac in unit 6b.
Reliability: When the variability in replicated results is very high, the reliability is relatively low. This maybe due to certain variables not being controlled of faulty experimental procedures. Therefore, controlling factors effectively will improve the reliability of your results.
That is all...cheers!!