Biology · BIOMOLECULES

The given diagrammatic representation illustrates various structural levels of proteins. Identify the structural level in which the long polypeptide chain is folded upon itself like a hollow woolen ball, which is absolutely necessary for the biological activities of proteins:

1. A
   Level (b) representing secondary structure
2. B
   Level (a) representing primary structure
3. C
   Level (c) representing tertiary structure
4. D
   Level (d) representing quaternary structure