Answer: The option that is not true is D) Each amino acid is specified by only one codon.
Codon can be defined as the sequence of three nucleotides ( present in DNA or mRNA) that corresponds to a particular amino acid. It helps in the process of translation as different amino acids ( that are linked to codons) are assembled to give a particular protein according to the sequence of codon.
There are 64 codons and 20 amino acids that make up the proteins present in the living systems. This indicates that several different codons can correspond to the same amino acid.
For instance, amino acid Valine is coded by four codons that is GUC, GUG, GUA, GUU.
Thus, option D) is incorrect.
Are you talking about like isotonic and hypertonic or are you asking what hypotonic solution means if it was hypotonic the cell would be expanding if it was hypertonic the cell would be shrinking which means more molecules would be going inward in the cell if it was hypertonic if it was hypotonic the molecules would go more on the outside in the water would come in