I have no idea what you mean with "functional unit". The SI has units to measure lots of different things; basically there are seven base units (such as the meter, the second, and the kilogram), and several dozen derived units, i.e., units derived from the base units, for example meters/second for speed.
(g) grams- is the unit used in the metric system.
The meter is in the metric system
A metric unit is a decimal unit of measurement of the metric system, based on meters and kilograms and seconds.
In the metric system, "centi" is a prefix: it is not a measurement unit of any kind.
The gram is a metric unit of mass.
(g) grams- is the unit used in the metric system.
Capillaries are referred to as the functional unit of the circulatory system.
The SI unit for mass in the metric system is the kilogram.
The meter is in the metric system
A metric unit is a decimal unit of measurement of the metric system, based on meters and kilograms and seconds.
Celsius is the metric unit. Kelvin is the International System(SI) unit.
There is no individual unit in the Metric system that is near one inch in the English system, I'm afraid.
In the metric system, "centi" is a prefix: it is not a measurement unit of any kind.
What metric unit would you use to measure a computer keyboard
Newtons is the basic metric system unit for weight
The gram is a metric unit of mass.
If, by 'metric system', you mean the 'SI system', then there is no base unit for volume. The unit for volume is called a 'derived unit', and it is the cubic metre (m3).