In science biomass is the most accurate measurement of the weight of an organism. As you may be aware most of the human body, about 70%, is water present in our renal system, circulatory system and in our cells; well this is the same with most living organisms and plants. The true weight of something cannot be determined unless all of this water is removed. This is the process of getting a biomass, the organism is dried out to remove all of water, thus in effect the true weight of the organism is given. The only real downside of this process is when it concerns living organisms, animal, rather than those from the plant kingdom, as the organism must be dead in order to find it biomass which is not preferable. yea it also is renewable.
Hope this helps,
Chloe
Biomass (with the rare exception of hydrothermal vent organisms) starts with photosynthesis, which is the creation of organic compounds by the use of energy from light (normally sunlight). Organisms which do this can then be eaten by other organisms, who can in turn be eaten by other organisms and so forth, giving rise to complex food chains. All organisms are composed of biomass, which is to say, biological matter.