1. I think it is bloodstream
2. I am not sure
It really depends, think of it as 2 light bulbs in each parent. if both light bulbs in both parents are switched on that means their genes that they inherited are only able to have brown eyed babies, although if just 1 of the 4 light bulbs are not on it allows the baby to have blue eyes.
C.3 vaccines help prevent diseases and stuff
The large bone in the upper arm is called the humerus. The shoulder blade is called the scapula and the collarbone is called the clavicle.