Q: A reaction has $$\Delta H = -50\ \mathrm{kJ/mol}$$ and $$\Delta S = -0.1\ \mathrm{kJ/(mol\cdot K)}. At$$ $$T = 298\ \mathrm{K}$$, what is $$\Delta G$$?

$$\Delta G = -50\ \mathrm{kJ/mol} - (298\ \mathrm{K} \times -0.1\ \mathrm{kJ/(mol\cdot K)}) = -50 + 29.8 = -20.2\ \mathrm{kJ/mol}$$

Question 1

Which scientist is credited with demonstrating that organic compounds can be synthesized from inorganic materials, thus challenging the concept of vitalism?

Accepted Answer

Friederich Wohler

Question 2

Which of the following best describes the 'RNA World' hypothesis in biochemistry?

Accepted Answer

RNA was the first molecule to store genetic information and catalyze reactions in early life forms.

Question 3

Which of the following is NOT one of Daniel Koshland's seven 'pillars of life'?

Accepted Answer

Photosynthesis

Question 4

Which of the following statements correctly differentiates prokaryotes from eukaryotes?

Accepted Answer

Prokaryotes lack membrane-bound organelles, while eukaryotes possess them.

Question 5

Which of the following best describes the hydrophobic effect in aqueous solutions?

Accepted Answer

Nonpolar molecules aggregate to minimize their contact with water, increasing the entropy of the system.

Question 6

Which equation is used to relate pH, pKa, and the ratio of conjugate base to acid in a solution?

Accepted Answer

Henderson-Hasselbalch equation: $$\mathrm{pH} = \mathrm{p}K_a + \log\left(\frac{[	ext{A}^-]}{[	ext{HA}]}ight)$$

Question 7

A protein has a pI (isoelectric point) of 6.5. At pH 8.0, what is the net charge of the protein likely to be?

Accepted Answer

Negative

Question 8

Which of the following statements about noncovalent interactions is TRUE?

Accepted Answer

Noncovalent interactions are generally weaker than covalent bonds but are essential for biological structure and function.

Question 9

Which of the following best explains why water can act as both a weak acid and a weak base?

Accepted Answer

Water can donate a proton to become $$\mathrm{OH}^- or $$accept a proton to become $$\mathrm{H}_3\mathrm{O}^+.$$

Question 10

A buffer system is most effective when:

Accepted Answer

The pH is close to the pKa of the buffering acid.

Question 11

Which of the following is the correct formula for Gibbs free energy change?

Accepted Answer

$$\Delta G = \Delta H - T \Delta S$$

Question 12

A reaction has $$\Delta H = -50\ \mathrm{kJ/mol}$$ and $$\Delta S = -0.1\ \mathrm{kJ/(mol\cdot K)}. At$$ $$T = 298\ \mathrm{K}$$, what is $$\Delta G$$?

Accepted Answer

$$\Delta G = -50\ \mathrm{kJ/mol} - (298\ \mathrm{K} 	imes -0.1\ \mathrm{kJ/(mol\cdot K)}) = -50 + 29.8 = -20.2\ \mathrm{kJ/mol}$$

Question 13

Which of the following best describes the difference between equilibrium constant ($$K) $$and reaction quotient ($$Q$$)?

Accepted Answer

$$K is $$calculated using equilibrium concentrations, while $$Q$$ uses current concentrations.

Question 14

Which of the following statements about ATP hydrolysis is TRUE?

Accepted Answer

ATP hydrolysis is thermodynamically favorable and is often used to drive unfavorable reactions via coupling.

Question 15

Which bond in ATP is considered a 'high energy phosphate' bond?

Accepted Answer

Phosphoanhydride bond between the beta and gamma phosphates

Question 16

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

Accepted Answer

Enzymes increase the rate of reactions without affecting the equilibrium position.

Question 17

Which of the following is a real-world application of gel electrophoresis in biochemistry?

Accepted Answer

Separating DNA fragments based on size for genetic analysis

Question 18

Which of the following best explains why the tendency toward equilibrium drives biological processes?

Accepted Answer

Biological systems move toward equilibrium to minimize free energy and maximize stability.

Question 19

Which of the following fields uses large-scale analysis of proteins to understand cellular functions?

Accepted Answer

Proteomics

Biochemistry Foundations: Structure, Interactions, and Energetics (Chapters 1–3)

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