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.
Polar molecules have trouble passing through the nonpolar part of the phospholipid bilayer. Ions require ion channels and is not as easy as those that simply just diffuse through the membrane. Ion channels might require energy, too... Not glucose because those are larger molecules.