Nitrogen is an essential constituent of which of the following?

Which of the following amino acids has the lowest iso-electric point $(pI)$?

The structure of protein that is unaffected by heating is ... .

Which from following is a protein of muscles?

Identify the essential amino acids from below $:$
$(A)$ Valine
$(B)$ Proline
$(C)$ Lysine
$(D)$ Threonine
$(E)$ Tyrosine
Choose the correct answer from the options given below $:$

The correct sequence of amino acids present in the tripeptide given below is