Flexi Says: Biomass is the material that comes from plants and animals that were recently living. Plant biomass makes up the majority of biomass in the biosphere. Biomass can be burned directly, such as setting fire to the wood. For as long as humans have had fire, people have used biomass for heating and cooking. People can also process biomass to make fuel, called biofuel. Biofuels are made from a variety of plant biomass, including farm waste and algae.