Which among the following $\alpha$-amino acids does $NOT$ have a chiral carbon atom?

Which of the following statements are correct?
$A$) $\alpha$-amino acids present in proteins are $L$-amino acids.
$B$) Amino acids contain both $-NH_2$ and $-COOH$ groups.
$C$) The number of amino groups and carboxylic groups is always the same in amino acids.
$D$) Tyrosine was first obtained from cheese.
Choose the correct alternatives from below:

Differentiate between globular and fibrous proteins.

Each polypeptide in a protein has amino acids linked with each other in a specific sequence. This sequence of amino acids is called . . . . . . structure of that protein.

Serine $(HOCH_2CH(NH_2)COOH)$ is an amino acid. The correct Fischer projection of $L$-serine is:

Which one of the following statements is correct?