Tryptophan self-controls its synthesis. If we have a large 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 answers the question.
Answer:
The plasma membrane is made up by a phospholipid bilayer with embedded proteins that separates the internal contents of the cell from its surrounding environment. Only relatively small, non- polar materials can easily move through the lipid bilayer of the plasma membrane.
Explanation:
I am going with x-rays; it is the most visible to the naked eye out of all the choices.
The answer is genetic drift.