The graph shows how the activity of an enzyme changes at different temperatures. Which
statement best describes what happens to the enzyme when the temperature of the reac-
tion increases to 45 degrees Celsius?
X = optimal temperature
Rate of reaction
20 30 40 50
Temperature / "C
А
The enzyme is used up and the reaction stops.
B
The enzyme begins to decrease the rate of the reaction.
С
The enzyme continues to increase the rate of the reaction.
D
The enzyme changes shape and can no longer speed up the reaction.