Scientists studied soybean plants grown in sunlit, controlled-environment chambers with a carbon dioxide (CO2) concentration of 700 μmol CO2/mol of air. The CO2 concentration in the chambers was approximately double that of normal concentrations of environmental CO2 . Photosynthetic rate is measured by the amount of CO2 exchanged in an area of leaf surface over time. The rate is directly influenced by the activity of the plant enzyme rubisco. During photosynthesis, rubisco fixes atmospheric carbon into an organic molecule as one of the first steps in the Calvin cycle. Scientists measured the amount of carbon fixation that occurred in the leaves of soybean plants grown at each temperature shown in Table 1. T (C) Carbon Fixation
25 91
30 96
35 93
40 104
45 71
50 59
Describe the effect on an enzyme of an increase in environmental temperature above the optimum temperature range of the enzyme.