Answer:
It is called the S-A node, or rather sinus node.
I think the answer is photosystem
it separates the inside of the cell from the environment outside and it controls substances moving in and out of the cell (selectively permeable)
Blood typing can identify if will is the father or not by the composition of the genotype and it’s compatibility within the parents.
Will can not be the parent as there is only one possible genotype composition of blood type AB being i^Ai^B.
