How does temperature affect enzymes?

Enzymes are proteins which catalyse (speed up without being used up) biological reactions. Each enzyme will only speed up one reaction as the shape of the enzyme molecule needs to match the shape of the molecule it reacts with (the substrate molecule). The part of the enzyme molecule that matches the substrate is called the active site. Temperature has a significant impact on enzymes, at low temperatures, enzyme reactions are slow. As temperatures rise, enzymes have more kinetic energy resulting in more collisions of enzymes with their specific substrate, meaning faster reactions. However every enzyme has an optimum temperature where the reaction is at its quickest, after this, the enzymes stop working. This is known as denaturing where the active site of the enzyme is affected, and it results in the slowing down of the reaction, which will eventually stop. Enzymes are involved in reactions during photosynthesis, protein production, digestion and many more. Explain to me how you would answer the following question: Explain how temperature affects crop yield in a green house? (3 marks) (June 2012)