Human's have 22 pairs of autosomes. Females have two copies of the x-chromosome.
Oceanic crust has been forming on Earth for over 4 billion years, all of the sea floor older than <span>about 200 million years. </span>
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 :)