Need help for biology as PCM student preparing for IAT

I am a pcm student taking drop for IISER and need help to study biology,if not all the syllabus then at least major,important and scoring chapters. Any seniors or anyone preparing can please recommend good and trusted platforms/teachers for this.

I am considering enrolling in sciastra courses but to my understanding jn their dropper batch the bio will be taught assuming the student already knows at least somewhat as it is a dropper batch.