Hello Aspirant ,

As per my experience ,Class 11 syllabus contains the basics which you'll need to understand the 12th syllabus. So it's very important and should not be skipped at all.

Refer the NCERTs for Biology and Chemistry. Organic chemistry basics are given elaborately in 11th textbooks.

In my opinion, before starting the 12th syllabus, you should go back and take a quick look at its basics in the 11th texts, so as to understand and better. And also take a quick revision at the end so that you fully understand each and every thing.

Try to also solve daily questions and numericals, to retain your knowledge and gain mastery over the topics.

hope this helps.

All The Best !!!