I have a low GPA even though I studied very hard for my exams. Could this possibly mean that I am not intellectually cut out for entrepreneurship since I can't even perform well in exams and academics?
No. GPA is a performance measure for academic pursuits. Memorization, rote, and perhaps a little critical thinking.
It's the real world out here, unsafe and prone to sudden breakdown. Your ability to interact with people, deal positively with the unexpected, and handle ongoing stress are far more important than regurgitation of some process upon command.
In the real world, you can always pay someone to learn the thing. Or take the time to look the thing up yourself. Memorization is not important. Problem-solving is.
Frankly if you were too methodical a person, I'd be more concerned about your entrepreneurial future than if you're spinny and prone to getting struck by new ideas. But any type of person can be an entrepreneur. The key issue is whether you can handle the stress. And no school can prepare you for that--even the one I went to, that made us wade through 10 and 11 courses a term, resulting in a 40% student failure rate.
Entrepreneurship is more than just hard work. Hard work is easy. If that's all it took, many more people would be rich. But the universe doesn't care how hard you work...nor how hard your competitors are working, either. Remember that on your journey.