Antiparallel and Parallel Beta Sheets

Practice: Silk fibroin contains predominantly β sheet conformation. Which of the following is true regarding its β sheets?

Practice: The diagram illustrates: 

Practice: The major reason that antiparallel β-sheets are more stable than parallel β-sheets is that the latter:

Practice: Which (phi, psi) pair of bond angles is closest to those of the residues shown in the figure below?

Practice: What type of β-sheet is presented in the figure below? Draw all hydrogen bonds between appropriate groups.

Practice: Draw a two-stranded antiparallel β-sheet with appropriate hydrogen bonding between the following peptides:                                   

1) L-A-D-Y.                   

2) G-A-G-A.