Thank you so much @ Marks

Marks willl usually matter for that very first job, since people don't have anything much else by which to judge you. 

Actually, not even my first job asked me for my marks; I got it because I knew something about a fairly esoteric niche that I had been interested in outside of my formal studies.  Sometimes you just luck into something like that.  But be prepared that people will care about marks for that first job.  Nobody else has ever asked me about my marks later; your job perfomance in your first job will matter more..

It does require more than knowledge though.  Any kind of relevant work experience and internship and volunteer work counts; it'll work in your favour.  Get it across that you can quickly pick up on new things, that you work well within a team.  Write about what you accomplished, not just what you did.  Have a great resume and cover letter for your application, customize the cover letter to the company to which you are applying -- and know important things about them.  Proof read!  Have somebody literate proof read!  Follow the application instructions.  Don't act like a special snowflake, expecting special treatment.

Good luck!