Macmillan Learning Enzymatic activity is known to be affected by temperature A study examined the activity rate in micromoles per second mol s of the digestive enzyme acid phosphatase in vitro at varying temperatures measured in kelvins K The findings are displayed in the following table For reference the range of 253 to 298 K corresponds to roughly 25 to 80 degrees Celsius or 77 to 176 degrees Fahrenheit Temperature K 298 298 298 303 303 303 308 308 308 313 313 313 Rate u mol s 0 04 0 05 0 05 0 08 0 08 0 08 0 11 0 13 0 11 0 18 0 20 0 19 Temperature K 318 318 318 323 323 323 323 328 328 333 333 333 Rate mol s 0 34 0 34 0 35 0 47 0 48 0 48 0 48 0 78 0 79 0 97 0 98 1 03 Temperature K 338 338 338 343 343 343 348 348 348 353 353 353 To access the complete data set click the link for your preferred software format Excel Minitab14 18 Minitab 18 JMP SPSS TI R Mac TXT PC TXT CSV CrunchIt Rate mol s 1 05 1 10 1 06 0 96 0 98 0 99 0 72 0 73 0 75 0 54 0 58 0 62 Use the software of your choice to make a scatterplot If you calculate the correlation based on the data provided you find r 0 81 check for yourself 1 M E Petersone et al The dependence of enzyme activity on temperature determination and validation of parameters Biochemical Journal 402 2007 pp 331 337 doi 10 1042 BJ20061143 Explain why the numerical value of the correlation is only moderately strong even though the scatterplot indicates that the effect of temperature on enzymatic activity is clear and very reliable As the value of r is more sensitive to scatter when the relationship is curved the moderate strength of the value of r is due to the scatter of points for higher temperature values The value of r does not have meaning because the relationship is clearly not linear The association is neither positive nor negative The moderate strength of the positive value of r is a consequence of the change in relationship direction from positive to negative with the higher temperature values Although the relationship between the variables is positive for most values the moderately strong positive value of r