Enzymes are denatured at high temperatures. They have an optimum temperature of 40 degrees Celsius. On the graph explaining how works can you tell me why the graph has a curve/dent in it?:o

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Are you just referring to the decreased activity seen after you exceed the optimal temp

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The idea is that as long as the enzyme structure is stable, a higher temp will help the reaction progress faster. Many chemical reactions proceed faster with a generally higher temp. but at some point the higher temps begin to destabilize the enzyme structure, and its structure is critical to its activity. So you'll see a generally upward sloping line for temp versus activity... it'll flatten out as you reach the optimal temp, and then activity will decrease and higher temps render the enzyme less stable and less effective.