Answer: Decomposers
Because, when organisms are broken down and decomposed, they are mixed in with the soil. Yes, you should add soil to a food web that depicts the food relationship in an ecosystem because not only is it a result of decomposition, it helps the producers grow, starting the food chain again.
Phospholipids are made up of fatty acids, glycerol, and phosphate.
If you're referring to the structure of a phospholipid, they are composed of a water-loving (hydrophilic) head and a water-fearing (hydrophobic) tail. The tail is made up of long chains of hydrogen and carbon molecules as well.