BS161 Exam 2024| Questions solved
100% Correct/Verified Solutions
Consider the reaction M + NADH + H+ → O + NAD+. What type of pathway likely uses this
reaction and why?
(A)A anabolic pathway because conversion of M to O is coupled to NAD+ production from
NADH.
(B)A catabolic pathway because the reaction M -->O is energetically favorable.
(C)An catabolic pathway because O is less complex than M.
(D)A anabolic pathway because it uses ATP. - ANSWER A
A - ANSWER Examine the following schematic of a metabolic pathway, in which A, B, C, and
D represent molecules in these reactions. As the reaction B → C occurs, product C
accumulates and makes the reaction B → C unfavorable. Based on the schematic, which of
the following would keep B → C favorable?
(A)The conversion of C to D, because this decreases the concentration of C
(B)The conversion of B to C, because this increases the concentration of C
(C)The conversion of D to C, because this increases the concentration of C
(D)The conversion of A to a molecule other than B, because this decreases the concentration
of B
C - ANSWER The enzyme that catalyzes the reaction shown should have what properties at
its active site?
(A)Positive charges, since both glutamic acid and ATP are positively charged at the pH of
the cell.
(B)Negative charges, since both glutamic acid and ATP are negatively charged at the pH of
the cell.
,(C)Positive charges, since both glutamic acid and ATP are negatively charged at the pH of
the cell.
(D)Negative charges, since both glutamic acid and ATP are positively charged at the pH of the
cell.
Which of the following is often true of the active sites of enzymes?
(A)The amino acids of active sites are adjacent in both the primary and tertiary structure.
(B)They typically bind to a wide range of substrate molecules to maximize their usefulness to
cells.
(C)They can bind to and position substrates in a way that encourages a chemical reaction
(D)The amino acids of the active site form primarily covalent bonds with substrate molecules. -
ANSWER C
The following reaction occurs in muscle cells under specific circumstances:
Pyruvate + NADH + H+ → Lactate + NAD+
If the ΔG of the forward reaction is negative under these circumstances, this means that:
(A)NAD+ is more abundant than NADH
(B)An enzyme is present to catalyze the reaction
(C)Over time, net lactate is converted to pyruvate
(D)Over time, net pyruvate is converted to lactate - ANSWER D
B - ANSWER The reaction shown is part of a metabolic pathway. What happens in this reaction?
(A)Carbon 2 is being reduced, NAD+ is being reduced.
(B)Carbon 2 is being oxidized, NAD+ is being reduced.
(C)Carbon 2 is being oxidized, NAD+ is being oxidized.
(D)Carbon 2 is being reduced, NAD+ is being oxidized.
, C - ANSWER The image shows a cell that is moving a solute in the direction indicated by the
arrow. This movement:
(A)Requires coupling to a favorable process because the cell is moving the solute with
the concentration gradient, which is favorable
(B)Requires coupling to a favorable process because there is no concentration gradient, so the
movement is unfavorable
(C)Requires coupling to a favorable process because the cell is moving the solute against
the concentration gradient, which is unfavorable
(D)Requires no coupling because there is no concentration gradient, so the movement is
favorable
Requires no coupling because the cell is moving the solute with the concentration
gradient, which is favorable
Some unfavorable reactions are coupled to a reaction that uses ATP. Which of the following
accurately describes how ATP is used in a coupled reaction?
(A)ATP is hydrolyzed, which releases heat to make the unfavorable reaction occur
(B)ATP is used to make an activated intermediate, and the activated intermediate is used
to make the final product
(C)ATP is first phosphorylated, which creates an unstable molecule that forces with unfavorable
reaction to occur
(D)ATP is used to make an activated intermediate, and the activated intermediate is used
to remake ATP - ANSWER B
B - ANSWER For the cell in the diagram below ΔGout = -17.1 kJ/mol. If the solute concentration
inside the cell were to increase, how would the ΔGout be affected?
(A)ΔGout would become less favorable
(B)ΔGout would become more favorable
(C)ΔGout would not change
(D)Not enough information to be able to predict
100% Correct/Verified Solutions
Consider the reaction M + NADH + H+ → O + NAD+. What type of pathway likely uses this
reaction and why?
(A)A anabolic pathway because conversion of M to O is coupled to NAD+ production from
NADH.
(B)A catabolic pathway because the reaction M -->O is energetically favorable.
(C)An catabolic pathway because O is less complex than M.
(D)A anabolic pathway because it uses ATP. - ANSWER A
A - ANSWER Examine the following schematic of a metabolic pathway, in which A, B, C, and
D represent molecules in these reactions. As the reaction B → C occurs, product C
accumulates and makes the reaction B → C unfavorable. Based on the schematic, which of
the following would keep B → C favorable?
(A)The conversion of C to D, because this decreases the concentration of C
(B)The conversion of B to C, because this increases the concentration of C
(C)The conversion of D to C, because this increases the concentration of C
(D)The conversion of A to a molecule other than B, because this decreases the concentration
of B
C - ANSWER The enzyme that catalyzes the reaction shown should have what properties at
its active site?
(A)Positive charges, since both glutamic acid and ATP are positively charged at the pH of
the cell.
(B)Negative charges, since both glutamic acid and ATP are negatively charged at the pH of
the cell.
,(C)Positive charges, since both glutamic acid and ATP are negatively charged at the pH of
the cell.
(D)Negative charges, since both glutamic acid and ATP are positively charged at the pH of the
cell.
Which of the following is often true of the active sites of enzymes?
(A)The amino acids of active sites are adjacent in both the primary and tertiary structure.
(B)They typically bind to a wide range of substrate molecules to maximize their usefulness to
cells.
(C)They can bind to and position substrates in a way that encourages a chemical reaction
(D)The amino acids of the active site form primarily covalent bonds with substrate molecules. -
ANSWER C
The following reaction occurs in muscle cells under specific circumstances:
Pyruvate + NADH + H+ → Lactate + NAD+
If the ΔG of the forward reaction is negative under these circumstances, this means that:
(A)NAD+ is more abundant than NADH
(B)An enzyme is present to catalyze the reaction
(C)Over time, net lactate is converted to pyruvate
(D)Over time, net pyruvate is converted to lactate - ANSWER D
B - ANSWER The reaction shown is part of a metabolic pathway. What happens in this reaction?
(A)Carbon 2 is being reduced, NAD+ is being reduced.
(B)Carbon 2 is being oxidized, NAD+ is being reduced.
(C)Carbon 2 is being oxidized, NAD+ is being oxidized.
(D)Carbon 2 is being reduced, NAD+ is being oxidized.
, C - ANSWER The image shows a cell that is moving a solute in the direction indicated by the
arrow. This movement:
(A)Requires coupling to a favorable process because the cell is moving the solute with
the concentration gradient, which is favorable
(B)Requires coupling to a favorable process because there is no concentration gradient, so the
movement is unfavorable
(C)Requires coupling to a favorable process because the cell is moving the solute against
the concentration gradient, which is unfavorable
(D)Requires no coupling because there is no concentration gradient, so the movement is
favorable
Requires no coupling because the cell is moving the solute with the concentration
gradient, which is favorable
Some unfavorable reactions are coupled to a reaction that uses ATP. Which of the following
accurately describes how ATP is used in a coupled reaction?
(A)ATP is hydrolyzed, which releases heat to make the unfavorable reaction occur
(B)ATP is used to make an activated intermediate, and the activated intermediate is used
to make the final product
(C)ATP is first phosphorylated, which creates an unstable molecule that forces with unfavorable
reaction to occur
(D)ATP is used to make an activated intermediate, and the activated intermediate is used
to remake ATP - ANSWER B
B - ANSWER For the cell in the diagram below ΔGout = -17.1 kJ/mol. If the solute concentration
inside the cell were to increase, how would the ΔGout be affected?
(A)ΔGout would become less favorable
(B)ΔGout would become more favorable
(C)ΔGout would not change
(D)Not enough information to be able to predict
