FRESHWATER   :   

Water without significant amounts of dissolved sodium chloride (salt). Characteristic of rain, rivers, ponds, and most lakes.

FUEL CELLS   :   

An electrochemical energy conversion device that produces electricity from external supplies of fuel (on the anode side) and oxidant (on the cathode side). Fuel cells differ from batteries in that they consume reactant, which must be replenished, while batteries store electrical energy chemically in a closed system.

FUNDAMENTAL NICHE   :   

The full range of environmental conditions (biological and physical) under which an organism can exist.

FUNDAMENTAL PARTICLES   :   

The particles like leptons, quarks and gauge bosons that do not contain any smaller component are known as fundamental particles.