DAT Biology: Cellular Metabolism 2 — Questions and Answers
Question 1: During glycolysis, which molecule is the direct net product of substrate-level phosphorylation per glucose?
- 2 net ATP (Correct answer)
- 4 net ATP
- 2 GTP
- 6 net ATP
Correct answer: 2 net ATP
Glycolysis produces 4 ATP but consumes 2 in the investment phase, for a net of 2 ATP.
Question 2: Which enzyme catalyzes the committed, rate-limiting step of glycolysis?
- Phosphofructokinase-1 (Correct answer)
- Hexokinase
- Pyruvate kinase
- Aldolase
Correct answer: Phosphofructokinase-1
PFK-1 catalyzes the irreversible, allosterically regulated committed step of glycolysis.
Question 3: Under anaerobic conditions in human muscle, pyruvate is converted to what to regenerate NAD+?
- Lactate (Correct answer)
- Ethanol
- Acetyl-CoA
- Oxaloacetate
Correct answer: Lactate
Lactate dehydrogenase reduces pyruvate to lactate, oxidizing NADH back to NAD+ for glycolysis to continue.
Question 4: Where does glycolysis occur within the eukaryotic cell?
- Cytoplasm (Correct answer)
- Mitochondrial matrix
- Inner mitochondrial membrane
- Nucleus
Correct answer: Cytoplasm
Glycolysis takes place entirely in the cytosol, requiring no membrane-bound organelle.
Question 5: How many carbon atoms does each pyruvate molecule contain?
- 3 (Correct answer)
- 2
- 6
- 4
Correct answer: 3
Glucose (6 carbons) is split into two 3-carbon pyruvate molecules.
Question 6: Which coenzyme is reduced during the glyceraldehyde-3-phosphate dehydrogenase step?
- NAD+ to NADH (Correct answer)
- FAD to FADH2
- NADP+ to NADPH
- ATP to ADP
Correct answer: NAD+ to NADH
This oxidation step transfers electrons to NAD+, forming NADH.
Question 7: An allosteric activator of PFK-1 that signals low cellular energy is:
- AMP (Correct answer)
- ATP
- Citrate
- NADH
Correct answer: AMP
High AMP indicates low energy charge and stimulates PFK-1 to increase ATP production.
DAT Biology: Cellular Metabolism 2
During glycolysis, which molecule is the direct net product of substrate-level phosphorylation per glucose?