Hello

Yes, optional / additional subjects means the same.

In cbse class 12th , you have your 5 main subjects and if you want you can go for 6th subject which is nothing but your optional or additional subject.

So, in case of additional /optional biology, it will be your 6th subject.

Your profile suggests that your you are a medicine aspirant  so I am guessing that you are asking this question in regards to neet I would like to tell you as of now the students with Biology as an additional subject or optional subject are eligible for Neet examination until Supreme Court gives its judgement after the judgement eligibility will depend upon the outcome of the judgement to so to be on the safe side it will be good to opt Biology as one of your main/core subjects

For your reference,

Here's the eligibility criteria for NEET :-

-----------) Qualification required :-As per Neet eligibility to be eligible you must be either appearing for 12th board examination  or should have passed 12th board examination from any recognised board with physics, chemistry ,biology/biotechnology and English as core subject.

† ††Important Note :- Students with Biology as an additional subject are also provisionally eligible for neet until Supreme Court gives its judgement over it.

-----------)  Percentage required :- You must get

• at least 50 % in aggregate of PCB i.e Physics, Chemistry and Biology/Biotechnology in 12th examination if belongs to general category

• at least 40% in aggregate of PCB if belongs to st/Obc/ Sc

• at least 45 % in aggregate of PCB in case of pwd candidates to be eligible.

-----------)  Age limit :-

• Lower age limit:- to be eligible for neet  one has to be at least 17 years old or more by 31st December in the year of appearing for the examination .

• Upper age limit :-The upper age limit  is 25 years as on the date of neet examination and there's relaxation of 5 years for obc ncl/SC/ST /PwBD students means upper age limit is 30 years for these categories.

†††† But since 2018, the case of upper age limit is pending in supreme court , and so there's no upper age limit as of now until supreme court gives its judgement over it.

-----------) There's no attempt limit for neet.

For detailed information about neet examination eligibility go through our page for which link is provided below; -

https://medicine.careers360.com/articles/neet-eligibility-criteria

Thank you