If you wish you can obviously use your previous marksheet. If you appear for the NIOS then its not like that, your all certificates will expire. But if you choose a course after your science which is science based and if you wish to get a job through it then there will be no use of your MA and other marksheets. But if you wish you can obviously use them as references for jobs.

To know more about the NIOS visit the link below:

https://school.careers360.com/articles/nios

I hope this answer helps. All the very best for your future endeavors!