CHEM 210 MODULE 7 EXAM QUESTIONS
AND CORRECT ANSWERS
2024/2025/2026 PORTAGE LEARNING
CHEM 210 M7 EXAM(NEWEST)
Thermodynamics & General Principles
Q1: A scientist uses the term flux regarding a biochemical pathway.
What does flux mean?
Answer: Flux is the rate of flow through a biochemical pathway.
Rationale: In biochemistry, flux measures the turnover rate of
molecules through a metabolic pathway, indicating how active the
pathway is at a given time.
Q2: A particular pathway breaks down proteins into amino acids. Is
this an anabolic or a catabolic pathway?
Answer: Catabolic.
Rationale: Catabolic pathways are involved in the breakdown of
complex molecules into simpler ones, which releases energy.
Q3: A biochemical metabolic pathway is a single reaction that
converts starting material into products. True or False?
Answer: False.
Rationale: A metabolic pathway is defined as a series of consecutive,
enzyme-catalyzed reactions, not just a single one.
Q4: What is the sign (+ or -) of ΔG for the breakdown of ATP to
ADP, and why is this sign important?
,Answer: The sign is negative (-). This indicates a spontaneous,
favorable reaction capable of powering other cellular processes.
Rationale: ATP hydrolysis releases energy, making it the primary
energy currency of the cell.
🍬 Glycolysis
Q5: What is the primary reactant (starting molecule) of glycolysis?
Answer: Glucose.
Rationale: Glycolysis is the metabolic pathway that breaks down one
molecule of glucose into two molecules of pyruvate.
Q6: How many reactions are in the glycolysis pathway?
Answer: 10.
Rationale: The pathway consists of 10 enzyme-catalyzed steps, divided
into a preparatory phase and a payoff phase.
Q7: What are the two phases of glycolysis, and how many reactions
are in each?
Answer: The preparatory phase (5 reactions) and the payoff phase (5
reactions).
Rationale: The preparatory phase consumes ATP to destabilize glucose,
and the payoff phase produces ATP and NADH.
Q8: How many ATP molecules are invested in the energy-investing
stage of glycolysis?
Answer: 2 ATP.
Rationale: One ATP is used by hexokinase to phosphorylate glucose,
and another is used by phosphofructokinase-1.
Q9: What is the net number of ATP gained from glycolysis?
Answer: 2 ATP.
Rationale: While 4 ATP are produced in the payoff phase, the net gain
is 2 because 2 ATP are consumed in the preparatory phase.
, Q10: In converting glucose to pyruvate, how many ATP or NADH
are produced in the 1,3-bisphosphoglycerate to 3-phosphoglycerate
step?
Answer: 2 ATP produced.
Rationale: In this step, two molecules of 1,3-BPG (one from each G3P)
each transfer a high-energy phosphate group to ADP, producing 2 ATP
via substrate-level phosphorylation.
Q11: In which reaction of glycolysis is ATP formed by the direct
transfer of a phosphate group from a metabolite to ADP?
Answer: The last reaction (phosphoenolpyruvate to pyruvate), a process
called substrate-level phosphorylation.
Rationale: Substrate-level phosphorylation is the direct enzymatic
transfer of a phosphate group from an intermediate substrate to ADP to
form ATP.
Q12: In glycolysis, when glucose enters a cell, it is immediately
phosphorylated. What is the enzyme and the phosphate donor?
Answer: The enzyme is hexokinase, and the phosphate donor is ATP.
Rationale: Hexokinase catalyzes the first committed step of glycolysis,
trapping glucose inside the cell.
Q13: In the preparatory phase, a 6-carbon compound is broken into
two 3-carbon fragments. What happens to the other 3-carbon
fragment (DHAP)?
Answer: DHAP (dihydroxyacetone phosphate) is converted into GAP
(glyceraldehyde-3-phosphate) by the enzyme triose phosphate
isomerase.
Rationale: Only GAP can continue through the payoff phase of
glycolysis, so DHAP must be isomerized to GAP.
Q14: Under anaerobic conditions, to which compound is pyruvate
converted?
Answer: Lactate (or ethanol and CO2 in yeast).
Rationale: This conversion regenerates NAD+ from NADH, which is
necessary for glycolysis to continue in the absence of oxygen.
AND CORRECT ANSWERS
2024/2025/2026 PORTAGE LEARNING
CHEM 210 M7 EXAM(NEWEST)
Thermodynamics & General Principles
Q1: A scientist uses the term flux regarding a biochemical pathway.
What does flux mean?
Answer: Flux is the rate of flow through a biochemical pathway.
Rationale: In biochemistry, flux measures the turnover rate of
molecules through a metabolic pathway, indicating how active the
pathway is at a given time.
Q2: A particular pathway breaks down proteins into amino acids. Is
this an anabolic or a catabolic pathway?
Answer: Catabolic.
Rationale: Catabolic pathways are involved in the breakdown of
complex molecules into simpler ones, which releases energy.
Q3: A biochemical metabolic pathway is a single reaction that
converts starting material into products. True or False?
Answer: False.
Rationale: A metabolic pathway is defined as a series of consecutive,
enzyme-catalyzed reactions, not just a single one.
Q4: What is the sign (+ or -) of ΔG for the breakdown of ATP to
ADP, and why is this sign important?
,Answer: The sign is negative (-). This indicates a spontaneous,
favorable reaction capable of powering other cellular processes.
Rationale: ATP hydrolysis releases energy, making it the primary
energy currency of the cell.
🍬 Glycolysis
Q5: What is the primary reactant (starting molecule) of glycolysis?
Answer: Glucose.
Rationale: Glycolysis is the metabolic pathway that breaks down one
molecule of glucose into two molecules of pyruvate.
Q6: How many reactions are in the glycolysis pathway?
Answer: 10.
Rationale: The pathway consists of 10 enzyme-catalyzed steps, divided
into a preparatory phase and a payoff phase.
Q7: What are the two phases of glycolysis, and how many reactions
are in each?
Answer: The preparatory phase (5 reactions) and the payoff phase (5
reactions).
Rationale: The preparatory phase consumes ATP to destabilize glucose,
and the payoff phase produces ATP and NADH.
Q8: How many ATP molecules are invested in the energy-investing
stage of glycolysis?
Answer: 2 ATP.
Rationale: One ATP is used by hexokinase to phosphorylate glucose,
and another is used by phosphofructokinase-1.
Q9: What is the net number of ATP gained from glycolysis?
Answer: 2 ATP.
Rationale: While 4 ATP are produced in the payoff phase, the net gain
is 2 because 2 ATP are consumed in the preparatory phase.
, Q10: In converting glucose to pyruvate, how many ATP or NADH
are produced in the 1,3-bisphosphoglycerate to 3-phosphoglycerate
step?
Answer: 2 ATP produced.
Rationale: In this step, two molecules of 1,3-BPG (one from each G3P)
each transfer a high-energy phosphate group to ADP, producing 2 ATP
via substrate-level phosphorylation.
Q11: In which reaction of glycolysis is ATP formed by the direct
transfer of a phosphate group from a metabolite to ADP?
Answer: The last reaction (phosphoenolpyruvate to pyruvate), a process
called substrate-level phosphorylation.
Rationale: Substrate-level phosphorylation is the direct enzymatic
transfer of a phosphate group from an intermediate substrate to ADP to
form ATP.
Q12: In glycolysis, when glucose enters a cell, it is immediately
phosphorylated. What is the enzyme and the phosphate donor?
Answer: The enzyme is hexokinase, and the phosphate donor is ATP.
Rationale: Hexokinase catalyzes the first committed step of glycolysis,
trapping glucose inside the cell.
Q13: In the preparatory phase, a 6-carbon compound is broken into
two 3-carbon fragments. What happens to the other 3-carbon
fragment (DHAP)?
Answer: DHAP (dihydroxyacetone phosphate) is converted into GAP
(glyceraldehyde-3-phosphate) by the enzyme triose phosphate
isomerase.
Rationale: Only GAP can continue through the payoff phase of
glycolysis, so DHAP must be isomerized to GAP.
Q14: Under anaerobic conditions, to which compound is pyruvate
converted?
Answer: Lactate (or ethanol and CO2 in yeast).
Rationale: This conversion regenerates NAD+ from NADH, which is
necessary for glycolysis to continue in the absence of oxygen.
