Final answer:
Animal-based foods supply all nine essential amino acids, while plant-based foods are usually deficient in one or more essential amino acids.
Step-by-step explanation:
Animal-based foods, such as eggs, milk, fish, and meat, supply all nine essential amino acids. They are considered complete proteins because they contain adequate amounts of all the essential amino acids. On the other hand, plant-based foods, such as wheat, rice, and corn, are usually deficient in one or more essential amino acids and are considered incomplete proteins. However, vegetarians can obtain all the essential amino acids by consuming a variety of plant-based foods that together provide the right combination of amino acids.