Keethi, if it doesn't ask you to upload your 12th marks list in the application form, then you have to submit your 12th marks list during document verification. KEA will set up documentation verification centres. This is the last year's KCET Helpline centres for you: http://kea.kar.nic.in/cet2019/Helpline_centers.pdf . So during the documentation verification, along with other documents, you have to take with you your 12th marks list.