I have also done the 3 core topics and option of communication. While relatively new to atarnotes, i always strive to answer peoples questions. I am not first in bio at the moment, although i am in the top 5.
(For communication, at time of writing we had just started outcome 5- sound)
I am on a Band 5 at the moment and have past siblings notes which have gotten them a Band 6, so I am able to answer most questions.
Just whatever you do, do not be afraid to ask questions! Questions are how we improve (both the one/s answering the question as well as the asker) and there is a fair chance that someone else has that question. Wouldnt it suck to not ask a question on that one achilles heel you have for a topic and then to get an 8 marker on it? So, lets ask up and then some mods can get on here with their advice too