I don't know if the problem is with my memory or my intelligence, please help?

I read, i understand but i can't remember stuff in the exam or when someone asks me. But its not like i don't know that. Like when someone asked me the signs of datura poisoning, i could not tell so many of them but when asked to describe them, after they reminded me of the names, i could. In the exam too, i keep on trying to remember, like what was it after that point.. But it seldom comes to my memory. What should i do?