At the cellular level, membranes; for the whole organism, the skin is what

Reproduction.

Explanation:

At the cellular level indicate that the living organisms are made up of the smallest building blocks called cell. It refer to unicellular organisms i.e organism with one cell.

At the cellular level, membranes; for the whole organism, the skin is Reproduction because a single parent cell divides into two cells (offsprings), two divides into four cells and so on. It is called cell division and cell reproduction because a single cell skin divides to produce many cells.

the cells uses some of the atoms of the glucose molecules to atp molecules. the atoms of the glucose molecules will then be converted into energy which will be eventually stored in atp. the energy produced which are stored in atp are coming from the glucose’s chemical bonds.