Hey Katadare,
Also if you want to know the distribution of marks, chem bio and physics contribute 80 points each to your isci mark whereas earth sci only contributes 40 points.
I was vehemently opposed to earth sci and wished we spent the time elsewhere, but I quickly learned that it's very interesting and helps you see the world around you in a different way.
In summary, you'll be fine (:
Cheers,
Jared