The spiral configuration of $\alpha$-helix and $\beta$-pleated sheet of polypeptide chains are held together by . . . . . . bonds to form the secondary structure of protein.

In the secondary structure of a polypeptide chain,the folding of the chain is due to which type of bond?

Match the following Column-$I$ with Column-$II$ and select the correct option.

Column-$I$ (Type of Amino Acid)	Column-$II$ (Example)
$(A)$ Polar and uncharged $R$ group	$(i)$ Methionine
$(B)$ Non-polar $R$ group	$(ii)$ Glutamic acid
$(C)$ Polar and negatively charged $R$ group	$(iii)$ Lysine
$(D)$ Polar and positively charged $R$ group	$(iv)$ Cysteine

Hemoglobin contains which of the following ions?

Which of the following molecules is amphoteric in nature?

Which of the following statement$(s)$ is/are true?
$(i)$ All amino acids contain one chiral centre.
$(ii)$ Some amino acids contain one, while some contain more chiral centres or even no chiral centre.
$(iii)$ All amino acids in proteins have $L$-configuration.
$(iv)$ All amino acids found in proteins have $1^{\circ}$ amino group.