Identify the basic $\alpha$-amino acid from the following.

Assertion : Disruption of the natural structure of a protein is called denaturation.
Reason : The change in colour and appearance of egg during cooking is due to denaturation.

The number of $>C=O$ groups present in a tripeptide $Asp-Glu-Lys$ is.......

The total number of basic groups in the following form of lysine is:

The number of essential amino acids in man is

Protein found in a biological system with a unique three-dimensional structure and biological activity is called a native protein. When a protein in its native form is subjected to a physical change like a change in temperature or a chemical change like a change in $pH$,denaturation of proteins takes place. Explain the cause.