Preparing for the BHU MSc entrance exam in Zoology is not very difficult as the syllabus comprises the basics you have already learned in BSc. 

The 4 most important domains of this entrance test are

1. Diversity 

2. Ecosystem 

3. Cell Biology 

4. Molecular Biology 

Strong command of these topics will guarantee your entrance. Moreover, a daily dose of the latest Digest and GK from some basic General studies books will get you some brownie points.

The best book for this entrance is Arihant’s 

Publication book for BHU MSc Zoology. 

Everything else depends on your own dedication and efforts. The key is not to give in to pressure and stay motivated throughout.