rapid chemical reaction of two or more substances with a characteristic liberation of heat and light; it is commonly called burning. The burning of a fuel (e.g., wood, coal, oil, or natural gas) in air is a familiar example of combustion.n its broad definition, combustion includes fast exothermic chemical reactions, generally in the gas phase but not excluding the reaction of solid carbon with a gaseous oxidant. Flames represent combustion reactions that can propagate through space at subsonic velocity and are accompanied by the emission of light.
They have a hydrophilic phosphate head and two hydrophobic hydrocarbon tails. Cell membranes are made up of a double layer of these phospholipid molecules. This is because in water the hydrophilic heads will face the water while the hydrophobic tails will be in the center because they face away from the water.The phospholipid bilayer makes the membrane very stable but also allows flexibility.hospholipid molecules make up the cell membrane and are hydrophilic (attracted to water) as well as hydrophobic (not attracted to water but are attracted to other hydrophobic tails).
In the cell membrane, hydrophilic heads orient to the inside and outside of the membrane, with the hydrophobic molecules inside. This gives the membrane its semi permeable fluid nature.n the cell membrane, hydrophilic heads orient to the inside and outside of the membrane, with the hydrophobic molecules inside. This gives the membrane its semi permeable fluid nature.