Explanation:
I think it should be C because increase in temperature increases molecular motion. Therefore the speed of the moving molecules of both enzymes as well as the substrate will be accelerated. This
will enhance the colliding probability for both enzyme active sites and substrate molecules and more collisions occur between the enzyme active sites and substrate molecules generate greater chances for the reaction to occur. This can continue up to a certain point, after which there is a rapid decline in enzyme activity. This point is referred to
as optimum temperature. When the temperature increases beyond the optimum temperature, the hydrogen bonds, ionic bonds and other weak chemical bonds of enzyme active sites may be disrupted.
This will result a change in the shape of the active site of enzyme which will alter the complementary nature of the active site of enzyme molecules. Therefore, the
complementary binding of enzyme active sites and substrate molecules will be prevented. The above event is called as denaturation of enzyme molecules.
Therefore the rate of enzyme catalyzed reaction or in this case, photosynthesis will start to decline when the temperature increases beyond the optimum temperature and stops completely at certain
temperature, although rate of collision will keep on increasing.
