Statement I: The codon 'AUG' codes for methionine and phenylalanine.

Statement II: 'AAA' and 'AAG' both codons code for the amino acid lysine.

In the light of the above statements, choose the correct answer from the options given below.

The correct option is Statement I is incorrect but Statement II is true.

Let us analyze both statements step-by-step:

1. Analysis of Statement I:
The codon AUG is a dual-purpose codon in the genetic code. It has two main functions:
- It acts as the initiation codon (start codon) for protein synthesis (translation).
- It codes specifically for the amino acid methionine.
Phenylalanine is coded by the codons UUU and UUC. Since AUG does not code for phenylalanine, Statement I is incorrect.

2. Analysis of Statement II:
The genetic code is degenerate, meaning that a single amino acid can be coded by more than one codon. The amino acid lysine is coded by two specific codons:
- AAA
- AAG
Since both AAA and AAG code for lysine, Statement II is true.

Therefore, Statement I is incorrect but Statement II is true.