The DNA is packaged... it starts by being wrapped around special protein molecules (histones). This forms a nucleosome.
The biosphere is everything. the whole planet. so all of the above is right
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 :)
Answer: A
Explanation: the ice age posed a new chalenge to deer mice and on the ice the preadators could spot the darker deer mice better than the light deer mice.
