Identify the essential amino acid from the following.

Assertion : Haemoglobin is an oxygen carrier.
Reason : Oxygen binds as $O_2^-$ to $Fe$ of haemoglobin.

Identify the $N$-terminal and $C$-terminal $\alpha$-amino acids respectively in the following polypeptide fragment: $Ala-Gly-Ser-Tyr-Gly$.

White precipitate is formed in

Out of the following,which is the best category to describe proteins?

Which of the following amino acids is basic in nature?