What are low biological value proteins and in which foods are they mainly found?

Proteins with a low biological value are proteins which do not significantly result in growth by the individual that eats them. This is usually because the amino acids in the protein are not all present in the right amount. Foods with proteins that have low biological value include almost all plants. For example, cereal grains are low in the amino acid lysine, and so have low biological value by itself. Legumes are low in methionine. The plant with the highest biological value protein is quinoa.