Hello Ayesha Shireen !

For scoring 300+ in biology you must be thorough with NCERT.Biology consist of lots of terms and facts to be remembered. So make charts tabulations and your own handwritten notes whenever required to make studying easier. Lessons like Animal Kingdom can be studied much easily and efficiently if the common features of various phylum is tabulated.Be clear with the concepts when it comes to lessons like Molecular basis of Inheritance and Cell division use google youtube for basics.Those lessons can be very interesting once you understand the content. Units like Animal Physiology requires so much memorization and should be revised frequently so make a good timetable

Differentiate the units and use different strategy for different units. Attend the full portion mock test for Biology part and analyze the unit that you are weak in. Work on those and enhance your score. Biology is a part where you can get maximum marks and make sure you give your best.

 Consult some good books or study materials and do the same.Solve MCQs related to the topic you have studied. It will definitely help you retain the concepts and information better.Solve previous years papera when you are confident enough.

Good luck