Final answer:
In wheat, lysine is considered a limiting amino acid, making wheat an incomplete protein source that doesn't provide enough of this essential amino acid.
Step-by-step explanation:
Wheat does not contain enough lysine for humans to synthesize proteins from wheat alone. Thus, in wheat, lysine is considered to be a limiting amino acid. Among the various types of proteins, those that do not provide adequate amounts of one or more of the essential amino acids, such as lysine in the case of wheat, are called incomplete proteins. When a diet consists primarily of incomplete proteins, it is important to combine different foods with complementary proteins to ensure an adequate intake of all essential amino acids. For example, combining grains that are deficient in lysine with legumes that contain lysine but are deficient in other amino acids can provide a well-rounded profile of essential amino acids.