Hello dear student !

To prepare for MSc zoology entrance exam for BHU, first of all, you need to focus on you graduation as most of the syllabus is from what you are studying in your graduation only. So just be regular with your studies. Also you can follow some good books such as Pathfinder fundamental of Life Sciences - part 1 and part 2. This book is really nice and helpful for most of the MSc. Zoology entrances. You can check the syllabus and prepare accordingly with focusing on the chapters which carry more weightage. You can also practice from the previous year's question papers. In this way you can prepare for the respective entrance exam.

Hope this will help you

All the best!