Often the first two chapters of a textbook orient to the specific branch of study within its broader field of knowledge. They also orient you to why the study is important. Further, they orient you to the foundational concepts that will underpin information in later chapters. Then they open the study of the topic with the first, most essential topics.
For instance, an ecology text might start with its place within the broader field of Earth sciences, then explain the importance and magnitude of the study of ecology. After that, foundational concepts such as sustainability, ecosystem, hydosystems, biospheres may be explained. This may be followed by an initial lesson on soil and the carbon cycle.
Therefore, these are the important sorts of orientational and introductory things you will want to know for your exam on Chapters 1 and 2.