Final answer:
To form a protein segment that is 9 amino acids long, 8 water molecules are removed, as each peptide bond formed between the amino acids through a condensation reaction releases one water molecule.
Step-by-step explanation:
If a protein segment is 9 amino acids long, this means that there will be 8 peptide bonds forming between these amino acids. Since the formation of each peptide bond releases one water molecule through a condensation reaction, we can deduce that 8 water molecules will be removed to create a protein segment that is 9 amino acids long.
Each peptide bond forms between the carboxyl group of one amino acid and the amino group of the next, and during this process, a dehydration synthesis occurs, resulting in the formation of a water molecule. This principle applies to the formation of all proteins, no matter their length, with one less water molecule than the number of amino acids due to one molecule of water being released for each bond formed between amino acids.