In biosynthesis, which amino acid serves as the source of the amino group for other amino acids?

A) D-phenylalanine
B) L-phenylalanine
C) racemic phenylalanine
D) L-glutamic acid
E) D-glutamic acid

Which amino acid has a phenol in its side chain?

A) tyrosine
B) tryptophan
C) isoleucine
D) asparagine
E) histidine