You are expected to produce 4 essays in the span of 3 hours for your typical exam. You get to choose those 4 from a paper of 12–15 questions. Each essay will typically be between 1200 and 2000 words, and there is (usually) no word limit (for closed-book exams) as time is the real limit to how much you can submit — those 45 minutes are over before you know it.
Tutorial essays typically mirror exams, though tutors may sometimes assign more convoluted questions and expect you to write a longer essay for the tutorial just to practice and get a better understanding of the topic.