<span>A soil horizon is a layer parallel to the soil surface</span><span>, whose physical characteristics differ from the layers above and beneath</span>
In terms of macromolecules, needed and utilized by organisms to carry out essential metabolic chemical reactions and for maintaining structure would be Lipids.
Lipid based molecules or Fats tend to store the most energy, as breaking chemical bonds connecting fatty acid chains of long hydrocarbons releases quite a bit of energy.
