13) At about pH 7 in most cells, what happens to the carboxyl R-group on an amino acid?

13) At about pH 7 in most cells, what happens to the carboxyl R-group on an amino acid? A) It acts as a base and gains a proton, giving it a positive charge. B) It acts as an acid and loses a proton, giving it a negative charge. C) It is oxidized and tends to act as an electron acceptor in redox reactions. D) It remains neutral, like water, and does not have a charge. 14) Why are polymerization reactions endergonic? Polymerization reactions A) reduce entropy B) release heat, making the reactant monomers move faster C) release energy D) are at equilibrium 15) Which of the following involves an increase in entropy? A) hydrolysis B) reactions that join monomers C) polymerization D) chemical evolution 16) Upon chemical analysis, a particular polypeptide was found to contain 100 amino acids. many peptide bonds are present in this protein? A) 101 B) 100 C) 99 D) 98 E) 97 17) What is the difference between a ribonucleotide and a deoxyribonucleotide? A) Ribonucleotides contain a phosphate group. B) Ribonucleotides have a hydroxyl group on the 2 carbon of their sugar subunit. C) Ribonucleotides contain a sugar with five carbon atoms. D) Ribonucleotides have a hydrogen atom on the I carbon of their sugar subunit. 18) What is/are the variable structure(s) of a nucleotide? A) the phosphate group B) the sugar C) the base D) the sugar and the base 19) What is the difference (if any) between the structure of ATP and the structure of the precursor of the A nucleotide in RNA? A) The sugar molecule is different. B) The nitrogen-containing base is different C) The number of phosphates is three instead of one. D) The number of phosphates is three instead of two. E) There is no difference.