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 partially dissociate, acting as 'sponges' for protons and minimizing pH changes.

Question 3

If the concentration of $$CO_2 in $$the atmosphere increases, what is the most likely effect on ocean acidity?

Accepted Answer

Ocean acidity will increase because dissolved $$CO_2$$ forms carbonic acid, releasing $$H^+$$ ions.

Question 4

Which chemical equation best represents the initial step of carbon dioxide dissolving in water and affecting ocean pH?

Accepted Answer

$$CO_2 + H_2O$$ \rightarrow H_2CO_3$$

Question 5

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

Accepted Answer

Shells dissolve more readily because $$H^+$$ ions react with carbonate ions.

Question 6

Which of the following equations describes the equilibrium involved in respiratory regulation of blood pH?

Accepted Answer

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

Question 7

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 decreases due to increased $$CO_2$$ loss; breathing into a bag increases $$CO_2$$ and helps restore pH.

Question 8

Which of the following is NOT a function of proteins in living organisms?

Accepted Answer

Encoding genetic information

Question 9

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

Accepted Answer

The side chain (R group)

Question 10

What type of bond forms between the amino group of one amino acid and the carboxyl group of another during protein synthesis?

Accepted Answer

Peptide bond (amide bond)

Question 11

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

Accepted Answer

Primary structure

Question 12

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 13

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 14

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

Accepted Answer

Hydrogen bonds between polar backbone atoms

Question 15

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

Accepted Answer

Their unique shapes disrupt the regular hydrogen bonding patterns required for these structures.

Question 16

Which interaction is most important for stabilizing the tertiary structure of a protein in an aqueous environment?

Accepted Answer

Hydrophobic interactions among nonpolar side chains

Question 17

What is the main driving force behind protein folding in water?

Accepted Answer

Hydrophobic effect, where nonpolar side chains cluster to minimize water cage entropy

Question 18

Which of the following statements about protein denaturation is correct?

Accepted Answer

Denaturation disrupts secondary, tertiary, and quaternary structures but leaves the primary structure intact.

Question 19

Which of the following best explains why hydrophobic (non-polar) residues are typically found in the interior of folded proteins?

Accepted Answer

Non-polar residues avoid water, clustering together inside the protein to maximize water entropy.

Water and the Chemistry of Life: Buffers and pH Regulation

Study Guide - Practice Questions