Is this sentence natural? Biology and Science are the same

We learn:

Ecosystem in Science class and DNA in Bio class.

B has a contrary belief that Biology is divided from Science but A thinks that these classes aren't the same.

The debate starts:

A: Science is not the same as Biology

B: But when I revise I combine these two subjects into one. Our head is stupid because he break this down into two subjects, forcing us to study 15 subjects. Actually, there are only 9 subjects we are actually learn but many chapters we have to study.