Many cells working together forms a tissue. Many tissues working together forms organs. Many organs working together forms organ systems. So it goes from general to most specific. Organ systems are needed in order for life. This proves that cells are the most basic units of life.
Glucose is classified as a monosaccharide.
(-ose means sugar.)
Yes it can kill brain cells. if you hold your breath for a short amount of time example 10 seconds it won't do any harm. but if you hold your breath for an extended time like a minute the cells will not get enough oxygen and eventually die. I hope I helped you