Questions about the ged (sections social studies and science)?

I have already taken and passed the reading section.

On Wednesday I go to take my writing, science and social studies portions.
I feel pretty confident I will pass the writing section.
I am so scared about science and social studies though.

I have been studying by using the book "master the ged". It seems so hard! I have been doing horribly.
But I'm wondering if the test is any easier than the book? Like, is it common sense/stuff you can just infer(?) I guess from pictures/diagrams they show, or do you actually have to know stuff? If that makes sense.