NETA Personal Trainer Practice Exam 2025 - Free Personal Trainer Practice Questions and Study Guide.

Complete proteins are those that provide all nine essential amino acids that the human body cannot synthesize on its own. Essential amino acids play a vital role in various bodily functions, including muscle repair, hormone production, and immune response. Sources of complete proteins typically include animal products such as meat, fish, dairy, and eggs, as well as some plant-based sources like quinoa and soy.

In contrast, options that suggest a protein containing only nonessential amino acids or only essential amino acids do not accurately reflect the definition of complete protein. Nonessential amino acids can be synthesized by the body, while essential amino acids must be obtained through diet. Additionally, stating that complete proteins contain no amino acids is incorrect, as proteins are fundamentally composed of amino acids. Hence, the presence of all essential amino acids defines a complete protein, making this understanding foundational in nutrition and fitness.