You may have to take many examinations and whilst some students prefer exams to coursework, many find the experience stressful, we want to change that. The purpose of exams is to demonstrate that you have understood the material that you have studied by applying it to new questions and contexts (the exam). Examiners are not trying to trick you, they want you to pass.
They expect you to answer the question set, NOT to write everything you know about the topic. You will be awarded better marks for focussed, relevant answers, which address all parts of the question and which are written in clear English.