The National Standard Examination in Biology (NSEB) is a prestigious examination that tests the knowledge and understanding of biology among school students in India. To prepare for this examination, it is essential to have the right resources, including textbooks. Here are some of the best biology books that can help you in your NSEB preparation:

1. "Biology: Concepts and Connections" by Neil A. Campbell and Jane B. Reece:
- This book provides a comprehensive overview of biology concepts and connects them to real-life applications.
- It covers a wide range of topics, including cell biology, genetics, evolution, ecology, and more.
- The content is presented in a clear and concise manner, making it easy to understand and retain.

2. "NCERT Biology Textbook for Class 11 and 12":
- The NCERT textbooks are highly recommended for the NSEB preparation as they follow the syllabus prescribed by the examination.
- The books provide a strong foundation in biology and cover all the essential topics in a structured manner.
- They include diagrams, illustrations, and examples to aid in understanding the concepts.

3. "Biology for NEET and Other Medical Entrance Examinations" by A.P. Singh:
- This book is specifically designed for students preparing for medical entrance examinations like NEET, which also covers the NSEB syllabus.
- It includes a vast array of practice questions, including previous years' question papers, to help students assess their understanding and improve their problem-solving skills.

4. "Objective Biology" by S. Chand:
- This book is focused on objective-type questions, which are commonly asked in competitive examinations like NSEB.
- It covers a wide range of topics and includes practice exercises with solutions to help students evaluate their knowledge and enhance their exam-taking skills.

Remember to supplement your study with additional resources such as reference books, online resources, and study guides to gain a comprehensive understanding of biology. Practice solving previous years' question papers and take mock tests to assess your preparation level and identify areas for improvement.