Question 1

What is the term for an amino acid form that has both a positively charged amino group and a negatively charged carboxylate group?

Accepted Answer

Zwitterion

Question 2

Which of the following best describes a zwitterion at physiological pH?

Accepted Answer

A molecule with both positive and negative charges but overall neutral

Question 3

Which functional groups are present in all standard amino acids?

Accepted Answer

Amino group and carboxyl group

Question 4

Which of the following equations correctly represents the ionization of a generic amino acid in water?

Accepted Answer

$$\mathrm{H_2N{-}CHR{-}COOH} \rightarrow H_3N^+{-}CHR{-}COO^-}$$

Question 5

Which property allows amino acids to act as buffers in biological systems?

Accepted Answer

Their ability to form zwitterions

Question 6

Which of the following is NOT a characteristic of a peptide bond?

Accepted Answer

It is easily broken by water at room temperature

Question 7

Which of the following best explains why amino acids can exist as enantiomers?

Accepted Answer

They have a chiral carbon atom (except glycine)

Question 8

A patient’s blood pH drops below 7.35. Which form of amino acid will predominate in their blood?

Accepted Answer

The cationic form ($$\mathrm{H_3N^+{-}CHR{-}COOH})$$

Question 9

Which of the following statements about isomers is correct?

Accepted Answer

Isomers have the same molecular formula but different structures

Question 10

Which of the following best describes the process of peptide bond formation?

Accepted Answer

A dehydration synthesis reaction between the carboxyl group of one amino acid and the amino group of another

Question 11

Which of the following is a real-life application of amino acids acting as zwitterions?

Accepted Answer

Maintaining the pH of blood plasma

Question 12

Which of the following best explains why glycine is not optically active?

Accepted Answer

It does not have a chiral center

Question 13

Which of the following is the correct general structure of an amino acid?

Accepted Answer

$$\mathrm{H_2N{-}CHR{-}COOH}$$

Question 14

Which of the following best describes an enantiomer?

Accepted Answer

A molecule that is a non-superimposable mirror image of another

Question 15

Which of the following is a consequence of the zwitterionic nature of amino acids in aqueous solution?

Accepted Answer

High melting points compared to non-ionic compounds

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Study Guide - Practice Questions