In most multicellular organisms, every cell carries the same DNA, but this genetic information is used in varying ways by different types of cells. In other words, what a cell does within an organism dictates which of its genes are expressed.
Most enlisted positions require four years of active duty. If you join the Navy through an officer program, you must serve at least four of your eight years on active duty. However, pilots and flight officers must serve a minimum of eight to 10 years of active duty. Dentists, Medical Service Corps officers and nurses must serve a minimum of three years of active duty.
Question: What is the maximum age to become an officer in the Military? Answer: By law, the maximum age for a commission is age 35. This is because a military officer must be able to have 20 years of service, to be retirement eligible by the maximum retirement age of 55. There are a few exceptions: Military medical officers and chaplains can be commissioned up to the age of 47 with waivers into their 50s (they also don't have to retire by age 55). Depending upon the need for doctors, psychologists, chaplains (all faiths), and legal officers as well, the maximum age can be waived.