State three factors which effect enzyme activity. (3)

With this question you really have to take into account how many marks you are given (in fact I'd say this is the case in most biology questions) as you want to make sure you have made one point per mark given. In this instance they have requested three factors worth three marks so I think it's safe to assume you should offer three quick answers and not waste time, especially on short answer questions like this when you'll probably want a bit more thinking time for longer questions in the paper. With this question you really want to have rope learnt three of these factors. As with a lot of questions of this length the papers will often repeat the questions so going over past papers is ESSENTIAL to doing well as you will have hopefully answered similar questions a few times before the exam avoiding scary surprises and calming your nerves. So the first answer you could offer is a change in temperature - this effects enzyme activity as increasing temperature causes the enzyme's active site to mutate (change shape) and so the enzyme cannot bind to the substrate, if the temperature is too cold the enzymes will lose kinetic energy (movement) and will not collide with the substrate fast enough to bind. A second answer is a change in pH - (most) enzymes work best at a neutral pH of 7 and a change in this optimum can also lead to a lose of shape in the active site. A third answer would be an increase in either/or enzyme and substrate concentration (you can write both for a mark each), this point is quite self explanatory in that the more substrates and enzymes you have the more they will bind, you need to be careful with terminology here and be sure to use the scientific word 'concentration' rather than amount. Finally, inhibitors effect the rate of enzyme activity - competitive inhibitors bind to the active site which means the enzyme cannot bind to the substrate, whilst non-competitive inhibitors bind to another site of the enzyme and cause it to lose its protein structure and this mutation of the active site means the substrate can no longer bind. So remember go over past papers to help you answer short questions like this quickly, giving you more time for more complex questions in the paper!