Final answer:
Complete proteins provide all essential amino acids, while plant-based foods are usually incomplete proteins. However, complementary proteins can be created by combining different plant-based foods to obtain all essential amino acids.
Step-by-step explanation:
Proteins can be classified as either complete or incomplete. Complete proteins provide adequate amounts of all nine essential amino acids, while incomplete proteins do not contain adequate amounts of one or more of the essential amino acids. Most plant-based foods are considered incomplete proteins, with a few exceptions such as soy. However, it is possible to pair foods containing incomplete proteins with different limiting amino acids to provide adequate amounts of the essential amino acids. These combined proteins are called complementary proteins.