Science Eligibility

Not possible, if you clear all the backlogs then you can try to pursue BCA.

Eligibility for B.Sc in medical radiology and imaging technology from Uttaranchal (P.G.) College of Bio-Medical Sciences and Hospital:
Qualification: 12th
Minimum Eligibility to Apply: 45%
Additional Details
Mandatory Subjects : Physics, Chemistry, Maths/Biology
Regards.

You should have at least 50% marks in your class 12th.

Sorry, I don't have any Idea about Sydenham college as such. But as per my knowledge, Sydenham accept scores more than 99% in MAT as it is the top most college. So, there acceptance ratio is also high.

Eligibility for a Marine Biologist
Educational
The minimum educational requirement for an entry-level job as a Marine biologist is Bachelor of Science degree with a focus on Marine biology. However, most preferred is a Masters degree in Marine biology. For research and university teaching positions, PhD in Marine biology is required.
Marine biology areas of study include systematics, ecology, anatomy, physiology, biochemistry, pathology, parasitology, reproduction and development, mariculture, ocean farming, pollution biology, energy resources and conservation.