This book was written to help the student of the 3rd Gymnasium in understanding the fundamental knowledge of Biology that the school textbook deals with. Each unit of this book consists of the following:
- Introduction to the theory: the theory of the specific unit is presented summarily, highlighting the most important elements.
- Understanding theory with questions and answers: the theory of each unit is analyzed in the form of answered questions, including the necessary diagrams and images.
- Answers to textbook questions: the answers to the questions of the textbook are provided, as well as the answers to the "Small research and assignments" and "Let's think" sections.
- Comprehension questions in the unit: additional questions are given for better understanding and deepening of each unit.
- Answers to comprehension questions in the unit: in this way, the student can evaluate their knowledge.
- Evaluation criteria: at the end of each chapter, an evaluation criterion is provided to facilitate the student during revision.

At the same time, images and diagrams are used to facilitate the understanding of basic biological concepts, as well as additional information that offers a more comprehensive approach and captures the student's interest.
At the end of the book, there is an Appendix that includes the answers to the questions of the "Workbook" and the "Laboratory guide". In addition, some simple experiments that can be conducted in the school laboratory are provided.