Question 1

Which of the following best explains why glycolysis is considered one of the most ancient metabolic pathways?

Accepted Answer

It predates both photosynthesis and the evolution of eukaryotes, and occurs in the cytoplasm without the need for organelles.

Question 2

During glycolysis, what is the net gain of ATP and NADH molecules per molecule of glucose?

Accepted Answer

$$2$$ ATP and $$2$$ NADH

Question 3

Which of the following statements about the regulation of glycolysis is correct?

Accepted Answer

Feedback inhibition by ATP slows glycolysis when cellular energy is abundant.

Question 4

In the absence of oxygen, muscle cells convert pyruvate to lactic acid. What is the primary purpose of this conversion?

Accepted Answer

To regenerate NAD$$^+ so $$glycolysis can continue.

Question 5

Which of the following best describes the role of NAD$$^+ in $$glycolysis?

Accepted Answer

NAD$$^+ is $$reduced to NADH, carrying electrons extracted from glucose.

Question 6

A patient is experiencing muscle fatigue during intense exercise. Which metabolic process is most likely responsible for the burning sensation in their muscles?

Accepted Answer

Production of lactic acid via anaerobic respiration

Question 7

Which of the following equations correctly represents the net reaction of glycolysis?

Accepted Answer

$$\mathrm{Glucose} + 2\ \mathrm{NAD}^+ + 2\ \mathrm{ADP} + 2\ \mathrm{P_i} \rightarrow 2\ \mathrm{Pyruvate} + 2\ \mathrm{NADH} + 2\ \mathrm{ATP} + 2\ \mathrm{H_2O} + 2\ \mathrm{H}^+$$

Question 8

Why is the reduction of NAD$$^+ to $$NADH during glycolysis considered 'uphill'?

Accepted Answer

Because it requires energy input, coupling with the oxidation of carbon to drive the reduction.

Question 9

Pyruvate is often described as a 'decision point' in metabolism. Which of the following best explains this concept?

Accepted Answer

Pyruvate can enter multiple metabolic pathways, including the citric acid cycle, fermentation, and amino acid synthesis.

Question 10

Which of the following is a direct consequence if a cell cannot regenerate NAD$$^+$$ under anaerobic conditions?

Accepted Answer

Glycolysis will stop, halting ATP production.

Question 11

In yeast cells, what is the end product of anaerobic respiration, and what is its significance for bread making?

Accepted Answer

Ethanol and CO$$_2$$; CO$$_2$$ forms bubbles that make bread rise.

Question 12

Which of the following best describes substrate-level phosphorylation?

Accepted Answer

Direct transfer of a phosphate group to ADP from a phosphorylated intermediate.

Question 13

A mutation causes a cell to have a non-functional enzyme at the 'investment' phase of glycolysis. What is the most likely outcome?

Accepted Answer

Glycolysis will halt, and the cell will not be able to metabolize glucose for energy.

Question 14

Which of the following is true regarding the fate of pyruvate in the presence of oxygen?

Accepted Answer

Pyruvate enters the mitochondria and is converted to acetyl-CoA for the citric acid cycle.

Question 15

Which of the following best explains why the citric acid cycle and electron transport chain are not used during intense exercise?

Accepted Answer

They are slower than glycolysis and require oxygen, which may be limited during intense exercise.

Question 16

Which of the following is an example of feedback inhibition in glycolysis?

Accepted Answer

High levels of ATP inhibit a key enzyme in glycolysis, slowing the pathway.

Question 17

Which of the following statements about the energy yield of glycolysis is correct?

Accepted Answer

Glycolysis produces a net gain of 2 ATP and 2 NADH per glucose molecule.

Question 18

Which of the following best describes the relationship between the oxidation of glucose and the reduction of electron carriers during glycolysis?

Accepted Answer

Glucose is oxidized, transferring electrons to NAD$$^+$$, which is reduced to NADH.

Question 19

Which of the following is a reason why glycolysis can proceed in the absence of mitochondria?

Accepted Answer

Glycolysis occurs in the cytoplasm and does not require membrane-bound organelles.

Cellular Respiration: Overview and Glycolysis

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