Which statement best defines an incomplete dietary protein in terms of essential amino acids?

• A. It lacks at least one essential amino acid in sufficient quantity to meet human needs.
• B. It contains no amino acids and therefore cannot support protein synthesis.
• C. It contains all essential amino acids in adequate amounts for human needs.
• D. It contains only essential amino acids and no nonessential amino acids.

Answer: (A)

Verified step by step guidance

1. Understand the concept of dietary proteins and their classification based on amino acid content. Proteins are made up of amino acids, some of which are essential, meaning the body cannot synthesize them and must obtain them from the diet.
2. Define an 'incomplete dietary protein' as a protein source that does not provide all essential amino acids in the amounts required by the human body for proper growth and maintenance.
3. Recognize that an incomplete protein lacks at least one essential amino acid or does not have it in sufficient quantity to meet human nutritional needs, which can limit protein synthesis.
4. Contrast this with a 'complete protein,' which contains all essential amino acids in adequate amounts to support human health.
5. Eliminate incorrect options by noting that a protein containing no amino acids cannot support protein synthesis, and a protein containing only essential amino acids is not typical; most proteins contain both essential and nonessential amino acids.