Answer:
Protozoology should be the answer.
The valence electrons of carbon are important because the valence give an element their bonding properties. If Carbon did not have as many, it would not be able to bond four times. or have many of the properties it possess.
Just say we have a big amount of tryptophan in the sense that it exceeds, tryptophan would act as a co-repressor which prevents synthesis of more enzymes for its production
Hope this helps :)
Magnesium Sulphate Monohydrate