What does hemoglobin in red blood cells primarily contain?

Which $\alpha$-amino acid can cross-link peptide chains?

Which of the following are protein fibers?

Name two $\alpha$-amino acids which form a dipeptide which is $100$ times more sweet than cane sugar?

In a linear tetrapeptide (constituted with different amino acids),the value of (number of amino acids) - (number of peptide bonds) is:

The $\alpha-$helix and $\beta-$pleated sheet structures of protein are associated with its: