Final answer:
The major species of alanine in solution at pH 7 is indeed the zwitterionic form, since its isoelectric point is within the pH range of 5.0 to 6.5.
Step-by-step explanation:
The statement that for the amino acid alanine, the major species in solution at pH 7 is the zwitterionic form is true. Amino acids, including alanine, have both acidic (carboxyl group) and basic (amino group) properties that can donate or accept protons, making them amphoteric molecules. The particular pH at which a given amino acid exists predominantly as a zwitterion is called the isoelectric point (pI), where the molecule has no net charge because the positive and negative charges balance out. For the majority of amino acids with neutral side chains, including alanine, the isoelectric point is in the range of pH 5.0 to 6.5, which means at pH 7, they exist mostly in their zwitterionic form. At pH values below the pI, the amino acid will tend to have a net positive charge, and at pH values above the pI, it will have a net negative charge.