Aresearcher has developed an assay to measure the activity of an important enzyme present in pancreatic cells growing in culture. she adds the enzyme’s substrate to a dish of cells and then measures the appearance of reaction products. the results are graphed as the amount of product on the y-axis versus time on the x-axis. the researcher notes four sections of the graph. for a short period of time, no products appear (section a). then (section b) the reaction rate is quite high (the slope of the line is steep). next, the reaction gradually slows down (section c). finally, the graph line becomes flat (section d). draw and label the graph, and propose a model to explain the molecular events occurring at each stage of this reaction profile.