A group of organs working together to perform a vital function in the body is known as a body system
tissue
cell
organelle

it's called an organ system

Explanation:

I looked it up in a book

answer: tell your parents first, and wait another couple of days. if it gets any worse, then you should call and ask. and you can always take pain meds if need be.

explanation:

answer: no, they are not.*

although rubber bands that contain excessive amounts of dye, toxins, or additives are sometimes toxic, most rubber bands do not cause any health issues. since they are typically made of latex, (a natural substance that is extracted from trees) they are not dangerous in any way if you chew them or accidentally ingest a piece of rubber band. however, chewing rubber bands does pose a choking hazard and is not a good habit to have.

*depending on the type of rubber band. the typical rubber bands that you see at stores are not toxic, but other types of rubber or latex that contains certain chemicals may be unhealthy and hazardous.