The diagram shows the shape of an enzyme and its substrate, before and after heating - HSC - SSCE Biology - Question 1 - 2016 - Paper 1

When the temperature increases, the kinetic energy of the molecules involved, including the enzyme and its substrate, increases. This can lead to a higher rate of successful collisions between the enzyme and substrate, which generally increases enzyme activity, up to an optimal temperature. However, if the temperature rises too much, enzymes can denature, leading to decreased activity or even total inactivity. Since the question specifies a temperature increase without further context, the most reasonable answer is that enzyme activity will increase, at least initially. Therefore, the correct answer is (B) increase.