Unit 1: Principles of biophysical chemistry and Carbohydrates - Practice Quiz

1 Which of the following is the strongest type of chemical bond found in biomolecules?

2 Weak interactions that arise between transiently induced dipoles in nearby atoms are called:

3 The tendency of nonpolar molecules to cluster together in water is known as the:

4 The pH of a neutral aqueous solution at is:

5 Which equation relates the pH of a buffer to the and the ratio of conjugate base to acid?

6 A buffer is most effective at resisting pH change when the pH is close to the:

7 Bioenergetics is best defined as the study of:

8 The molecule commonly referred to as the "energy currency" of the cell is:

9 A reaction that releases free energy and proceeds spontaneously is described as:

10 For a spontaneous reaction, the change in Gibbs free energy () must be:

11 In enzyme kinetics, (the Michaelis constant) represents the substrate concentration at which the reaction velocity is:

12 Enzymes increase the rate of a biochemical reaction by:

13 In a coupled reaction, an energetically unfavorable reaction is driven forward by:

14 Hydrolysis of ATP typically transfers which chemical group in coupled reactions?

15 Which cellular organelle is the primary site of ATP production in eukaryotic cells?

16 In plants, the organelle that transduces light energy into chemical energy is the:

17 Carbohydrates that cannot be hydrolyzed into simpler sugars are called:

18 Which disaccharide is composed of glucose and fructose?

19 Two sugars that differ in configuration around a single carbon atom are called:

20 The main storage polysaccharide in animals is:

21 A buffer is prepared with acetic acid and sodium acetate. Given , what is the approximate pH of this buffer?

22 A buffer has maximum buffering capacity when:

23 For a reaction at equilibrium, which statement about the standard free energy change is correct?

24 If a reaction has , what does this indicate about the equilibrium constant at standard conditions?

25 The hydrolysis of ATP to ADP has . If it is coupled to a reaction with , what is the net of the coupled process?

26 Which non-covalent interaction is primarily responsible for the exclusion of nonpolar molecules from water and drives protein folding?

27 The strength of van der Waals interactions depends on distance approximately as:

28 For a first-order reaction, if the half-life is minutes, what fraction of the reactant remains after minutes?

29 The half-life of a first-order reaction is:

30 Which of the following best describes an exergonic reaction?

31 In oxidative phosphorylation, ATP synthase acts as an energy transducer by converting:

32 Two sugars that differ in configuration at only one chiral center (other than the reference carbon) are called:

33 A monosaccharide with chiral carbons can have how many possible stereoisomers?

34 The and forms of D-glucose that differ only at the anomeric carbon (C-1) are known as:

35 A carbohydrate that yields two to ten monosaccharide units upon hydrolysis is classified as a:

36 Which of the following is a ketohexose?

37 Which property allows glucose to reduce Fehling's or Benedict's reagent?

38 Which disaccharide is a non-reducing sugar because both anomeric carbons are involved in the glycosidic bond?

39 Maltose is composed of two glucose units joined by which glycosidic linkage?

40 Which structural feature distinguishes cellulose from starch (amylose)?

41 A buffer is prepared containing acetic acid () and sodium acetate. If of strong acid (HCl) is added to of this buffer, what is the resulting pH? (Assume no volume change)

42 For a reaction at , the standard free energy change . If the actual concentrations are and , what is the actual ? (Use )

43 Glucose phosphorylation () is coupled to ATP hydrolysis (). What is the equilibrium constant for the coupled hexokinase reaction at ? (Use )

44 An enzyme has and . In the presence of a competitive inhibitor, the apparent becomes . At a substrate concentration of (with inhibitor present), what fraction of is the reaction velocity?

45 A ketohexose in its open-chain form has how many chiral centers, and how many stereoisomers does the entire family of open-chain ketohexoses contain?

46 Which statement best explains why the hydrophobic effect is largely entropically driven in protein folding?

47 The mitochondrial matrix pH is and the intermembrane space pH is , with a membrane potential (negative inside). What is the approximate total proton-motive force (PMF) at ? (Use per pH unit)

48 For D-glucose, the specific rotation of the pure -anomer is and the -anomer is . At equilibrium mutarotation gives . What is the approximate percentage of the -anomer at equilibrium?

49 For an enzyme following Michaelis–Menten kinetics, a Lineweaver–Burk plot yields a y-intercept of and an x-intercept of . What are and ?

50 Which of the following disaccharides is non-reducing, and why?

51 A reaction has and . Above what temperature does this reaction become non-spontaneous () under standard conditions?

52 Glycogen and amylopectin are both branched glucose polymers. What structural difference primarily accounts for glycogen's greater suitability for rapid glucose mobilization?

53 In the ATP synthase, if the c-ring contains 10 c-subunits and each catalytic cycle produces 3 ATP per full rotation, how many protons are translocated per ATP synthesized?

54 The strength of hydrogen bonds in biological macromolecules is highly dependent on geometry. What is the optimal donor–H···acceptor angle for a maximally stable hydrogen bond?

55 A carbohydrate yields two different monosaccharides on complete hydrolysis, does not reduce Fehling's solution, and is not hydrolyzed by -glucosidase but is cleaved by invertase. Which carbohydrate is it?

56 Phosphoric acid has three values: , , and . Which conjugate acid–base pair provides the best buffering capacity at physiological pH (), and what is the approximate ratio of base to acid?

57 Under cellular conditions, ATP hydrolysis has but the actual is often near . Which factor primarily accounts for this more negative actual value?

58 D-glucose and D-mannose differ only in the configuration at C2. What term describes this relationship, and what process interconverts them via a common enediol intermediate?

59 For a first-order reaction, the rate constant is . How long does it take for the reactant concentration to fall to of its initial value?

60 The standard free energies of hydrolysis are: phosphoenolpyruvate (PEP) and ATP . For the pyruvate kinase reaction (PEP + ADP → pyruvate + ATP), what is ?