Question 1

Which of the following statements best describes the role of oxygen in the electron transport chain?

Accepted Answer

Oxygen is the ultimate electron acceptor, receiving electrons at the end of the chain to form water.

Question 2

During glycolysis, the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate is thermodynamically unfavorable. How does the cell drive this reaction forward?

Accepted Answer

By coupling the reaction to ATP hydrolysis, which releases energy.

Question 3

Which enzyme is responsible for the phosphorylation of glucose in the liver, and why is its Km higher than other hexokinases?

Accepted Answer

Hexokinase 4 (glucokinase); its high Km ensures phosphorylation only when glucose levels are elevated, preventing depletion of blood glucose.

Question 4

Which of the following best explains why NADH and FADH2 are considered 'taxicabs' in cellular metabolism?

Accepted Answer

They transport electrons from metabolic pathways to the electron transport chain, becoming oxidized and reduced in cycles.

Question 5

Which of the following is TRUE regarding the regulation of glycolysis and gluconeogenesis?

Accepted Answer

Hexokinase, phosphofructokinase, and pyruvate kinase are regulated in glycolysis, while gluconeogenesis uses different enzymes for the irreversible steps.

Question 6

A patient with a deficiency in the debranching enzyme would most likely have difficulty mobilizing which type of carbohydrate?

Accepted Answer

Glycogen, because the debranching enzyme is required to cleave alpha-1,6 branch points.

Question 7

Which of the following best describes the difference between maltose and cellobiose?

Accepted Answer

Maltose is a disaccharide with an alpha-1,4 linkage, while cellobiose has a beta-1,4 linkage, making cellobiose indigestible by human enzymes.

Question 8

Which of the following reactions is catalyzed by pyruvate dehydrogenase?

Accepted Answer

Conversion of pyruvate to acetyl-CoA with the release of CO2 and production of NADH.

Question 9

Which of the following best describes the function of the pentose phosphate pathway?

Accepted Answer

It produces NADPH for reductive biosynthesis and ribose-5-phosphate for nucleotide synthesis.

Question 10

Which of the following statements about ATP hydrolysis is CORRECT?

Accepted Answer

ATP hydrolysis releases energy due to the resonance stabilization and electrostatic repulsion of phosphate groups.

Question 11

Which of the following is a reducing sugar, and how can it be detected?

Accepted Answer

Glucose; detected by its ability to reduce Cu$$^{2+} to Cu$^+ in $$Benedict's reagent.

Question 12

Which of the following best explains why cellulose cannot be digested by humans?

Accepted Answer

Cellulose contains beta-1,4 linkages, and humans lack the enzyme to hydrolyze these bonds.

Question 13

Which of the following is an example of an epimer pair?

Accepted Answer

Glucose and galactose, differing at the C-4 position.

Question 14

Which of the following best describes the effect of insulin on glycolysis?

Accepted Answer

Insulin promotes glycolysis by increasing the concentration of fructose 2,6-bisphosphate, which activates phosphofructokinase.

Question 15

Which of the following is TRUE regarding the citric acid cycle?

Accepted Answer

It occurs in the mitochondrial matrix and produces NADH, FADH2, and GTP (or ATP) per acetyl-CoA.

Question 16

Which of the following best describes the mechanism by which ATP synthase produces ATP?

Accepted Answer

ATP synthase utilizes the proton gradient across the inner mitochondrial membrane to drive conformational changes that favor ATP formation.

Question 17

Which of the following equations correctly relates the change in free energy ($$\Delta G) to $$the change in reduction potential ($$\Delta E) in a $$redox reaction?

Accepted Answer

$$\Delta G = -nF\Delta E$$

Question 18

Which of the following best describes the role of UDP-glucose in glycogen synthesis?

Accepted Answer

UDP-glucose is an activated glucose donor that facilitates the formation of glycosidic bonds during glycogen synthesis.

Question 19

Which of the following best explains the effect of high ATP levels on phosphofructokinase (PFK) activity?

Accepted Answer

High ATP levels inhibit PFK, decreasing glycolytic flux.

Module 3 Lectures

Guida di studio - Domande di pratica

Study guide - Flashcard