Question 1

Which of the following best describes the role of buffers in biological systems?

Accepted Answer

Buffers minimize changes in pH by reacting with added acids or bases.

Question 2

Why are weak acids and bases considered effective biological buffers?

Accepted Answer

They do not fully dissociate, allowing them to absorb or release protons as needed.

Question 3

If atmospheric $$CO_2$$ levels increase, what is the most likely effect on ocean acidity?

Accepted Answer

Ocean acidity will increase, lowering the pH.

Question 4

What happens to calcium carbonate ($$CaCO_3) $$shells in marine organisms as ocean acidity increases?

Accepted Answer

Shells dissolve more easily because $$CO_3$$^{2-}$$ ions are depleted.

Question 5

Which chemical equation best represents the buffering of blood pH involving carbon dioxide?

Accepted Answer

$$H^+ + $$HCO_3$$^- \rightleftharpoons H_2CO_3 \rightleftharpoons H_2O + CO_2$

Question 6

A person is hyperventilating. What happens to the pH of their blood, and why is breathing into a paper bag a common remedy?

Accepted Answer

Blood pH increases (alkalosis); the paper bag helps retain $$CO_2$$, restoring pH balance.

Question 7

Which of the following is NOT a major function of proteins in cells?

Accepted Answer

Storage of genetic information

Question 8

Which part of an amino acid is responsible for its unique chemical properties?

Accepted Answer

The side chain (R group)

Question 9

What type of chemical reaction links amino acids together to form a polypeptide?

Accepted Answer

Condensation (dehydration synthesis)

Question 10

Which level of protein structure is LEAST affected by disruption of hydrogen bonding?

Accepted Answer

Primary structure

Question 11

A single amino acid substitution in hemoglobin (E6V) leads to sickle cell disease. What is the molecular basis for this effect?

Accepted Answer

The mutation causes hemoglobin tetramers to form sticky fibers when not carrying oxygen.

Question 12

Which force is primarily responsible for the formation of secondary structure elements (alpha helices and beta sheets) in proteins?

Accepted Answer

Hydrogen bonds between backbone atoms

Question 13

Why are glycine and proline uncommon in alpha-helices and beta-sheets?

Accepted Answer

They disrupt the regular hydrogen bonding pattern due to their unique shapes.

Question 14

Which interaction is most important for stabilizing the tertiary structure of proteins in aqueous environments?

Accepted Answer

Hydrophobic interactions among nonpolar side chains

Question 15

Which of the following statements about protein folding is TRUE?

Accepted Answer

Protein folding is driven primarily by the hydrophobic effect, minimizing water cage entropy.

Question 16

Which of the following amino acid substitutions is most likely to be silent (not change protein properties)?

Accepted Answer

Arg (R) to Lys (K)

Question 17

Which of the following best explains why nonpolar (hydrophobic) amino acids are typically found in the interior of folded proteins?

Accepted Answer

Nonpolar amino acids minimize energetically costly water cages by aggregating in the protein core.

Question 18

Which type of bond is formed between the sulfur atoms of two cysteine residues, stabilizing protein structure?

Accepted Answer

Disulfide (covalent) bond

Question 19

Which level of protein structure involves multiple polypeptide chains interacting to form a functional protein?

Accepted Answer

Quaternary structure

Water and the Chemistry of Life: Buffers and pH Regulation

Study Guide - Practice Questions