Final answer:
Amino acids must be present in any food item that contains protein, since they are the building blocks of proteins.
Step-by-step explanation:
If you have identified protein in a food item in the laboratory, the food item must also contain amino acids. Proteins are made up of long chains of amino acids, which are the building blocks of proteins. The sequence of amino acids in the protein determines its structure and function. This is why different proteins in the body have different roles - for example, some help with muscle contraction, while others play key roles in our immune system or act as enzymes to facilitate biochemical reactions.
It's important to understand that glucose is a simple sugar and is not a direct building block of proteins. Lipids are fats and are also not direct components of proteins. Similarly, nucleotides are the building blocks of nucleic acids, not proteins. Therefore, out of the options provided, amino acids are what must be present in a food item also containing protein.