How many water molecules are formed if valine, thereonine, alanine, and glycine are joined

3 molecules of water will be formed.

Explanation:

When an amino acid is linked with another amino acid by peptide bond then a molecule of water is eliminated.

         When valine will join with thereonine at that one water molecule gets eliminated.

         when val-thr interacts with alanine at that second water molecule is being eliminated.

           Finally when val-thr-ala joins with glycine then the third water molecule is eliminated.

            So it can be concluded that  these four amino acids are joined by three peptide bonds along with loss of three molecules of water.