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 due to the formation of more hydrogen ions ($$H^+) $$from dissolved $$CO_2.$$

Question 4

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

Accepted Answer

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

Question 5

Which chemical equation best represents the buffering action of bicarbonate in blood?

Accepted Answer

$$H^+ + $$HCO_3$$^- \rightarrow H_2CO_3 \rightarrow 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) because $$CO_2 is $$lost; breathing into a bag increases $$CO_2$$ and lowers pH.

Question 7

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

Accepted Answer

Storage of genetic information

Question 8

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

Accepted Answer

Condensation (dehydration synthesis)

Question 9

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

Accepted Answer

The side chain (R group)

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 type of interaction is primarily responsible for stabilizing secondary structure elements 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

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

Question 14

What is the primary driving force behind protein folding in aqueous environments?

Accepted Answer

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

Question 15

Which of the following statements about protein tertiary structure is correct?

Accepted Answer

It involves interactions between R groups, including hydrophobic, ionic, and covalent bonds.

Question 16

Which of the following amino acids is most likely to be found on the surface of a folded protein in water?

Accepted Answer

Serine (polar)

Question 17

Which process is most likely occurring when the clear liquid egg white turns solid white upon heating?

Accepted Answer

Protein denaturation due to disruption of tertiary and secondary structure.

Question 18

Which of the following best explains why nonpolar amino acid residues are typically found in the interior of folded proteins?

Accepted Answer

Nonpolar residues aggregate to minimize contact with water, driven by the hydrophobic effect.

Question 19

Which of the following is NOT a common mechanism for protein denaturation?

Accepted Answer

Addition of amino acids

Water and the Chemistry of Life: Buffers and pH Regulation

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