Q: Which of the following best describes the main purpose of fermentation in cells?

To oxidize NADH back to NAD\textsuperscript{+} for glycolysis

Q: A muscle cell is deprived of oxygen during intense exercise. Which metabolic pathway will it favor and why?

Lactate fermentation, because it regenerates NAD\textsuperscript{+} for glycolysis

Question 1

Which of the following best describes the main purpose of fermentation in cells?

Accepted Answer

To oxidize NADH back to NAD	extsuperscript{+} for glycolysis

Question 2

A muscle cell is deprived of oxygen during intense exercise. Which metabolic pathway will it favor and why?

Accepted Answer

Lactate fermentation, because it regenerates NAD	extsuperscript{+} for glycolysis

Question 3

Which enzyme is most important for the regulation of glycolysis and is allosterically inhibited by high levels of ATP?

Accepted Answer

Phosphofructokinase-1 (PFK-1)

Question 4

Cancer cells often favor fermentation even in the presence of oxygen. What is this phenomenon called, and what is its consequence?

Accepted Answer

Warburg effect; increased glucose processing and uptake

Question 5

Which of the following is NOT a product of fermentation?

Accepted Answer

Acetyl CoA

Question 6

During gluconeogenesis, which step involves the conversion of pyruvate to phosphoenolpyruvate (PEP), and what is required for this process?

Accepted Answer

Step 1; requires ATP and GTP

Question 7

Which molecule stimulates glycolysis but inhibits gluconeogenesis?

Accepted Answer

AMP

Question 8

A patient is injected with a radiolabeled glucose analogue for a PET scan. Which metabolic pathway is being exploited to visualize cancer cells?

Accepted Answer

Glycolysis and fermentation (Warburg effect)

Question 9

Which of the following statements about gluconeogenesis is TRUE?

Accepted Answer

It uses up 4 ATP and 2 GTP per glucose synthesized

Question 10

Which enzyme is responsible for converting fructose-6-phosphate (F6P) to fructose-2,6-bisphosphate (F2,6BP) and is activated when unphosphorylated?

Accepted Answer

Phosphofructokinase-2 (kinase activity)

Question 11

Which process allows other monosaccharides, such as pentoses, to enter glycolysis?

Accepted Answer

Pentose phosphate pathway converts them into glycolytic intermediates

Question 12

Which of the following is a correct equation for the net ATP and GTP consumption in gluconeogenesis per glucose molecule synthesized?

Accepted Answer

$$4 \mathrm{ATP} + 2 \mathrm{GTP}$$

Question 13

Which enzyme is unique to gluconeogenesis and is responsible for converting pyruvate to oxaloacetate?

Accepted Answer

Pyruvate carboxylase

Question 14

Which of the following regulatory molecules inhibits glycolysis but stimulates gluconeogenesis?

Accepted Answer

Acetyl CoA

Question 15

Which process describes the breakdown of storage carbohydrates using a phosphate instead of water?

Accepted Answer

Phosphorolysis

Question 16

Which enzyme is activated by phosphorylation and removes phosphate from F2,6BP back to F6P?

Accepted Answer

Fructose-2,6-bisphosphatase (phosphatase activity)

Question 17

Which of the following is a correct description of the Cori cycle?

Accepted Answer

Lactate produced in muscle is transported to the liver, converted to pyruvate, and then to glucose via gluconeogenesis

Question 18

Which of the following is TRUE regarding the regulation of phosphofructokinase-2 (PFK-2)?

Accepted Answer

PFK-2 phosphatase activity is activated by phosphorylation

Question 19

Which of the following is a multi-step problem: If a cell is exposed to high levels of ATP and low levels of AMP, what will happen to glycolysis and gluconeogenesis?

Accepted Answer

Glycolysis will be inhibited and gluconeogenesis will be stimulated

Pyruvate Metabolism, Fermentation, and Gluconeogenesis: Regulation and Pathways

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