Why is 1-6 greater than 1-8 but less than 1-3?

Because when subtracting a larger number from a smaller number you end up with a negative number. The "higher" the negative number really means that it is a smaller value. Therefore -8 < -5 < -2

It is true that organism need food. but cells do not need food. the energy required by the cell for various chemical activities is released by mitochondria in the form of atp (adenosine triphosphate). atp is know as energy currency of the cell.hope it