Final answer:
The claim that only one aminoacyl-tRNA synthetase exists for each amino acid is false; some amino acids can have multiple corresponding synthetases across different species.
Step-by-step explanation:
The statement that only one aminoacyl-tRNA synthetase exists for each amino acid is False. While it is true that at least one type of aminoacyl-tRNA synthetase exists for each of the 20 amino acids, some amino acids can be attached to their corresponding tRNAs by more than one type of synthetase, especially across different species. These enzymes are crucial for protein synthesis, as they ensure that each amino acid is properly attached to its corresponding tRNA, a process known as 'charging' the tRNA.