A lactic acid test is a blood test that measures the level of lactic acid made in the body. Most of it is made by muscle tissue and red blood cells.
A biofuel is a fuel that is produced through contemporary biological processes, such as agriculture and anaerobic digestion, rather than a fuel produced by geological processes such as those involved in the formation of fossil fuels, such as coal and petroleum, from prehistoric biological matter.
The important difference between Biofuel and fossil fuels, is that Biofuel is renewable. Fossil fuels are in imminent danger of running out, or becoming economically non-viable. Biofuel can be produced from a number of different compounds including proteins, fats, and alcohols.