Cell signaling can be classified to be mechanical and biochemical based on the type of the signal. 1  Mechanical signals are the forces exerted on the cell and the forces produced by the cell. These forces can both be sensed and responded by the cells. Biochemical signals are the biochemical molecules such as proteins, lipids, ions and gases.
1 You must be an American citizen at least 18 years of age (or 21 years in some states). 2  You must be able to pass a drug test and in some cases, a physical endurance exam. 3  Bailiffs are expected to have clean criminal records and be model citizens [source: CV Tips ].
A: To become a customs broker, you must have a US citizenship, over the age of 21, clear a background check, and clear the brokers examinations with a satisfactory score of 75% or higher. All customs brokers must have an understanding of entry procedures, duty taxes, fees for imported goods, and fines.: You must at least complete a bachelor's degree program in order to become a customs agent. In some cases, a year of graduate coursework after your bachelor's degree may also be required. A degree with any major is generally acceptable, but preferable fields of study include criminal justice and law.