Answer:
The immune system has a vital role: It protects your body from harmful substances, germs and cell changes that could make you ill. It is made up of various organs, cells and proteins.
If you have type A blood then you must have at least one copy of the A allele. However, you could also have two copies of the A allele within type A blood. The genotype, therefore, would be either AO (if they have 1 A allele) or AA (if they have 2 A alleles).
The brain stem is the answer that you are looking for
Answer:
Indicator species, organism—often a microorganism or a plant—that serves as a measure of the environmental conditions that exist in a given locale. ... For example, greasewood indicates saline soil; mosses often indicate acid soil. Tubifex worms indicate oxygen-poor and stagnant water unfit to drink.
