Question 1

Which of the following best describes the net equation for 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 2

During glycolysis, which enzyme catalyzes the irreversible phosphorylation of glucose to glucose-6-phosphate?

Accepted Answer

Hexokinase

Question 3

Which step in glycolysis is considered the committed step, and why?

Accepted Answer

Conversion of fructose-6-phosphate to fructose-1,6-bisphosphate, because it commits the molecule to glycolysis

Question 4

Which of the following best explains the role of NAD+ in glycolysis?

Accepted Answer

NAD+ is reduced to NADH during the oxidation of glyceraldehyde-3-phosphate

Question 5

In the citric acid cycle, which enzyme catalyzes the conversion of isocitrate to α-ketoglutarate, and what is the significance of this reaction?

Accepted Answer

Isocitrate dehydrogenase; it produces NADH and releases CO2

Question 6

Which of the following statements about the electron transport chain is correct?

Accepted Answer

Complex IV reduces oxygen to water

Question 7

How many ATP molecules are produced from the complete oxidation of one molecule of glucose under aerobic conditions?

Accepted Answer

30-32

Question 8

Which of the following best describes the role of the malate-aspartate shuttle in cellular metabolism?

Accepted Answer

It transfers reducing equivalents from cytosolic NADH into the mitochondria

Question 9

Which enzyme is responsible for the conversion of pyruvate to oxaloacetate in gluconeogenesis, and what cofactor does it require?

Accepted Answer

Pyruvate carboxylase; biotin

Question 10

Which of the following statements about the pentose phosphate pathway (PPP) is true?

Accepted Answer

The PPP generates NADPH and ribose-5-phosphate for biosynthetic reactions

Question 11

Which of the following is a key regulatory enzyme in glycolysis that is allosterically inhibited by ATP?

Accepted Answer

Phosphofructokinase-1 (PFK-1)

Question 12

What is the main function of coenzyme Q (ubiquinone) in the electron transport chain?

Accepted Answer

It transfers electrons between Complex I/II and Complex III

Question 13

Which of the following best explains why gluconeogenesis stops at glucose-6-phosphate in most tissues but not in the liver?

Accepted Answer

Most tissues lack glucose-6-phosphatase, so glucose-6-phosphate cannot be converted to free glucose

Question 14

Which of the following reactions in the citric acid cycle is directly coupled to the production of GTP (or ATP)?

Accepted Answer

Conversion of succinyl-CoA to succinate

Question 15

Which statement best describes substrate-level phosphorylation?

Accepted Answer

ATP is generated by the transfer of a phosphate group from a high-energy substrate directly to ADP

Question 16

Which of the following is a major difference between glycolysis and gluconeogenesis?

Accepted Answer

Glycolysis is catabolic, while gluconeogenesis is anabolic

Question 17

Which of the following best describes the chemiosmotic theory?

Accepted Answer

ATP synthesis is driven by a proton gradient across the inner mitochondrial membrane

Question 18

Which enzyme catalyzes the committed step of the pentose phosphate pathway?

Accepted Answer

Glucose-6-phosphate dehydrogenase

Question 19

Which of the following best explains the importance of the futile cycle in metabolism?

Accepted Answer

It allows simultaneous synthesis and breakdown of glucose, generating heat and regulating metabolic flux

Question 20

Which of the following statements about the regulation of the citric acid cycle is correct?

Accepted Answer

High levels of ATP and NADH inhibit key enzymes of the cycle

Biochemistry Study Guide: Glycolysis, Citric Acid Cycle, Electron Transport Chain, Oxidative Phosphorylation, Pentose Phosphate Pathway, and Gluconeogenesis

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