A system is a collection of and other body parts that work together to carry out one of the body's major functions. Cells
Tissues
Organs
Bones

you are who you are and no one can change that about you. for one being lesbian is not a crime and two you are still great no matter who you like. the people that you like does not effect who you are as a person. as for why you are like that no one can answer. the only explanation i can give you is that it was who you were meant to be.

i have already answered this one it's a bachelor's degree in most cases