Q: Which equation is used to relate pH, $pK_a$, and the ratio of conjugate base to acid in a buffer system?

$\mathrm{pH} = pK_a + \log \left( \frac{[\text{A}^-]}{[\text{HA}]} \right)$

Question 1

Which of the following best explains why Brownian motion is essential for cellular biochemical processes?

Accepted Answer

It provides the thermal energy necessary for random molecular collisions that drive biochemical interactions.

Question 2

Water is a polar molecule. Which property of water is most directly responsible for its ability to form hydrogen bonds?

Accepted Answer

The unequal distribution of charge between the oxygen and hydrogen atoms.

Question 3

Which of the following weak interactions is most affected by the dielectric constant of the surrounding medium?

Accepted Answer

Electrostatic interactions

Question 4

The hydrophobic effect is crucial for which of the following biological processes?

Accepted Answer

Protein folding and membrane formation

Question 5

According to the Second Law of Thermodynamics, why do nonpolar molecules cluster together in aqueous solutions?

Accepted Answer

Clustering increases the entropy of water molecules.

Question 6

Which of the following statements about buffers is correct?

Accepted Answer

Buffers are acid-base conjugate pairs that resist changes in pH.

Question 7

A patient’s blood pH drops to 7.1 after intense exercise. If $[\mathrm{HCO}_3^-] = 8\ \mathrm{mM}$ and $pK_a = 6.1$, what is the concentration of $\mathrm{CO}_2$ in the blood? Use the Henderson-Hasselbalch equation.

Accepted Answer

$0.8\ \mathrm{mM}$

Question 8

Which equation is used to relate pH, $pK_a$, and the ratio of conjugate base to acid in a buffer system?

Accepted Answer

$\mathrm{pH} = pK_a + \log \left( \frac{[	ext{A}^-]}{[	ext{HA}]} ight)$

Question 9

Which of the following best describes the role of functional groups in biomolecules?

Accepted Answer

They confer specific chemical properties to biomolecules.

Question 10

During intense exercise, why does the concentration of $\mathrm{CO}_2$ in blood decrease, potentially leading to acidosis?

Accepted Answer

Increased metabolism produces more $\mathrm{CO}_2$, which shifts the equilibrium and lowers $\mathrm{CO}_2$ concentration as it is converted to $\mathrm{HCO}_3^-$ and $\mathrm{H}^+$.

Question 11

Which of the following is NOT a weak interaction commonly found in biochemical systems?

Accepted Answer

Covalent bonds

Question 12

A solution contains $[\mathrm{HCO}_3^-] = 8\ \mathrm{mM}$ and $[\mathrm{CO}_2] = 0.8\ \mathrm{mM}$. If $pK_a = 6.1$, what is the pH of the solution? (Use the Henderson-Hasselbalch equation.)

Accepted Answer

$7.1$

Question 13

Which of the following scenarios would most likely disrupt the structure of a protein in a living cell?

Accepted Answer

A significant change in pH away from the protein’s optimal range

Question 14

Which of the following best describes the relationship between $\mathrm{CO}_2$ and $\mathrm{HCO}_3^-$ in blood?

Accepted Answer

$\mathrm{CO}_2$ acts as the conjugate acid of $\mathrm{HCO}_3^-$

Question 15

Which of the following is a direct consequence of the hydrophobic effect in biological systems?

Accepted Answer

Formation of lipid bilayer membranes

Question 16

A researcher adds a strong acid to a buffered solution. What is the expected outcome?

Accepted Answer

The pH will change only slightly due to the buffer’s action.

Question 17

Which of the following best explains why changes in pH can be fatal to living organisms?

Accepted Answer

Changes in pH can alter the structure and function of biomolecules, disrupting essential biochemical processes.

Question 18

Which of the following is the correct chemical equilibrium describing the relationship between carbon dioxide and bicarbonate in blood?

Accepted Answer

$\mathrm{CO}_2 + \mathrm{H}_2\mathrm{O} \rightleftharpoons \mathrm{H}_2\mathrm{CO}_3 \rightleftharpoons \mathrm{H}^+ + \mathrm{HCO}_3^-$

Question 19

Which of the following is a real-life consequence of acidosis resulting from intense exercise?

Accepted Answer

Headaches, nausea, and dizziness

Biochemistry: A Short Course 1

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