Hello!
B. Sc. in second year consists of two papers, paper three and paper four. Both the papers comprise of 150 marks and the rest of the 50 marks make the practical paper.
In paper three, you have to study about vertebrates (chordate), its major phyla, different classes anf important members of each of those classes. Paper four comprises of majorly three topics, which are morphology, comparative Anatomy and embryology.
For both the papers, one can refer a common book which is easy to understand and contains a wide amount of vital information for the students. These are :-

• Modern Textbook of Zoology VERTEBRATES by K. L. Kotpal
  
• For practical paper you can refer Practical Zoology VERTEBRATES by S. S. Lal
  

I hope this was beneficial to you, good luck!