Hello Pranav!

No! Studying biology is not compulsory if you are opting for math based courses. If you want to take branches like Computer Science, Eletronics in B.Tech then instead of biology you can opt for CS, electronics in 11th and 12th. For branches like biotechnology, environmental engineering you must have prerequisite knowledge in biology. However, if you are unsure of what course you might take after 12th then biology can be safer option.