Which statement correctly defines incomplete proteins?

Which statement correctly defines incomplete proteins?

• A. Proteins lacking all essential amino acids
• B. Proteins with all essential amino acids
• C. Proteins derived exclusively from plants
• D. Proteins that are not used for growth

Answer: (B)

Incomplete proteins are those that do not supply all of the essential amino acids in adequate amounts. Since nine essential amino acids must come from the diet, a protein is considered incomplete if it lacks one or more of these amino acids (or provides them in insufficient amounts). Many plant-based foods fall into this category, which is why combining different plant proteins (complementary proteins) can provide a complete amino acid pattern. In contrast, a complete protein contains all nine essential amino acids in sufficient amounts.

Incomplete proteins are those that do not supply all of the essential amino acids in adequate amounts. Since nine essential amino acids must come from the diet, a protein is considered incomplete if it lacks one or more of these amino acids (or provides them in insufficient amounts). Many plant-based foods fall into this category, which is why combining different plant proteins (complementary proteins) can provide a complete amino acid pattern. In contrast, a complete protein contains all nine essential amino acids in sufficient amounts.