Don't forget to include the impact of global deforestation in your discussion of the enhanced greenhouse effect. Your understanding of the enhanced greenhouse effect should be related to the work you have done on fossil fuel energy sources and the increasing need for their replacement with renewable energy forms, like solar, biomass, wind, hydrogen gas and geothermal. One of the problem areas many students have is mixing the issue of ozone depletion in the stratosphere with the issue of global warming. But this does not make the planet warmer. In fact, in Unit 3 you should steer clear of any mention of the hole in the ozone layer.
Exam preparation begins from day one of the course.
All the concepts and areas you cover in class can be included in the exams. Make sure you understand material covered each week - if you are unsure about a concept, ask your teacher for help. As in other science subjects, you will have to complete two exams this year. Try to become familiar with the type of information the exam will contain, and the way various types of questions need to be answered. It may sound strange, but make sure you can write answers that clearly explain what you want to say - many students have trouble with this.