Assertion: t-RNA complexed with amino acid is called 'charged'.Reason: Aminoacid is linked to t-RNA through its amino group.

The assertion and the reason given are partially correct.

Assertion: t-RNA complexed with amino acid is indeed referred to as 'charged' or 'aminoacyl tRNA'. This is because the tRNA molecule is carrying or 'charged' with an amino acid for protein synthesis.

Reason: However, the reason is not entirely accurate. The amino acid is not linked to the tRNA through its amino group. Instead, it is linked through its carboxyl group. This bond formation is catalyzed by an enzyme called aminoacyl-tRNA synthetase. This enzyme ensures that the correct amino acid is paired with the correct tRNA molecule. Once the amino acid is attached to the tRNA, the tRNA is considered 'charged' and ready to participate in protein synthesis.