how could you classify one's job duties into one NOC subcatalog since there is n

[xxjal2000]

in NOC system, since there is only job duty description for one or two titles but not for all titles.
so how could i find if my job duty fall into one subtitile?
for example, in 2121 Biologists and related scientists, There are 131 titles. however, there are only two job description, one for the general one and one for microbiologist.
if i am a regulatory toxicologist under NOC 2121, in this case, how could i make sure my duties fall into NOC2121 and gain points for work experience during FSW application?
thanks!