The NCERT biology textbook for class 12 consists of a total of sixteen chapters. These are all conveniently divided into five main units so that students can quickly identify the most crucial sections and allocate their time accordingly. There are five units, as was previously stated. Unit 1 deals with reproduction, Unit 2 with genetics and evolution, Unit 3 with biology and human welfare, Unit 4 with biotechnology and its uses, and Unit 5 deals with ecology and the environment.