Final answer:
An incomplete protein is a protein that lacks one or more essential amino acids. It generally comes from plant sources and can be made complete by combining different plant sources.
Step-by-step explanation:
An incomplete protein is a protein that doesn't contain all the essential amino acids necessary for human nutrition. These proteins usually come from plant sources, such as grains or legumes. Unlike complete proteins, which contain all the essential amino acids, incomplete proteins lack one or more of these amino acids. An example is rice, which is low in the amino acid lysine. However, combining different plant sources can provide all the essential amino acids needed, making the diet complete.
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