Science

Hi,
You need not to worry. BCA eligibility is to possess an aggregate of 50% in your 10+2 or to clear entrance exams (if any). Your aggregate must include English subject.You need to check if the college where you want the admission has any entrance exam or not.
Try to check the web sites of some good colleges where all details of entrance are mentioned clearly. I was browsing the website of Lovely Professional University, for my friend to check the scholarships, they have clearly mentioned the criteria for admission to various courses. You can check details from the website of such colleges.So you need to have English and a pass percentage of at least 50% in your XIIth for BCA. You can browse the sites of some colleges for details.

There is no specific percentage of marks required of 12th for admission in B.Sc. course in asked College. However, the eligibility criteria is given below.
Eligibility criteria: A student passing the H.S.C. Examination conducted by the Maharashtra State Board for Secondary and Higher Secondary Education, Mumbai Divisional Board in the SIX subjects specified below or from another equivalent Board of Secondary Education or any other statutory examining body, is eligible for admission to the First Year of the Senior college in Arts / Science/Commerce Course.
(a) English
(b) Any one of the Modern Indian Languages (Marathi/ Hindi)
(c) Any four of the optional subjects for Arts, Sciences and Commerce courses as specified by the H.S.C. Board, Pune.
Therefore, from above you can get admission here.