A plough (UK) or plow (US; both /ËplaÊ/) is a tool or farm implement used in farming for initial cultivation of soil in preparation for sowing seed or planting to loosen or turn the soil. Ploughs were traditionally drawn by working animals such as horses or cattle, but in modern times are drawn by tractors.
Polar/Nonpolar Regions. In a biological membrane, the phospholipids are organized into a bilayer, which serves as the framework in which the other components of the membrane are embedded.
1 Phospholipids consist of a glycerol molecule, two fatty acids, and a phosphate group that is modified by an alcohol. 2  The phosphate group is the negatively-charged polar head, which is hydrophilic.  The fatty acid chains are the uncharged, nonpolar tails, which are hydrophobic.