The specificity of trypsin is determined by on the enzyme. The specificity of elastase is determined by on the enzyme. Three amino acids: Asp, His and Ser, of form a triad to cleave peptide bonds of a substrate.

Another Asp in something like a deep pocket; a superficial amino acid binding pocket with either a slight neutral side, neither elastase nor trypsin.  

Explanation:

The homologs with chymotrypsin include trypsin but mostly elastase. As either a central amino acid, chymotrypsin encompasses serine.

measuring light intensity

light meters can be used to measure light intensity. the meter is held at the soil surface and pointed in the direction of the maximum light intensity, and then the meter is read.

errors can be made when measuring light intensity by accidentally shading the light meter. the reliability of the results can be checked by taking many samples.