Who proposed the most widely accepted classification system for amino acids?

What are the types of the four polypeptide chains present in the structure of hemoglobin?

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.

Which of the two groups of the following formula is involved in peptide bond formation between different amino acids?

Identify the incorrect statement regarding conjugated proteins.

What does $L$ indicate in $L$-lysine and $L$-malic acid?