Question 1

Which of the following best describes the main difference between catabolic and anabolic pathways in metabolism?

Accepted Answer

Catabolic pathways break down complex molecules to release energy, while anabolic pathways use energy to build complex molecules from simpler ones.

Question 2

During glycolysis, which of the following steps directly generates ATP via substrate-level phosphorylation?

Accepted Answer

The conversion of phosphoenolpyruvate (PEP) to pyruvate

Question 3

A patient with a deficiency in glucose-6-phosphatase is unable to complete which metabolic pathway, leading to hypoglycemia during fasting?

Accepted Answer

Gluconeogenesis

Question 4

Which of the following statements about ATP is correct?

Accepted Answer

ATP acts as the universal energy currency by coupling exergonic and endergonic reactions.

Question 5

Which of the following best explains why the electron transport chain (ETC) is essential for ATP production in aerobic organisms?

Accepted Answer

The ETC creates a proton gradient across the inner mitochondrial membrane, which drives ATP synthesis via ATP synthase.

Question 6

A defect in Complex I of the electron transport chain would most likely result in which of the following?

Accepted Answer

Decreased proton motive force and reduced ATP synthesis

Question 7

Which of the following equations correctly represents the standard free energy change ($$\Delta G^\circ') $$for a reaction?

Accepted Answer

$$\Delta G^\circ' = -RT \ln K_{eq}$$

Question 8

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

Accepted Answer

Phosphofructokinase-1 (PFK-1)

Question 9

A patient presents with muscle cramps and exercise intolerance. Laboratory tests reveal an inability to break down glycogen. Which enzyme is most likely deficient?

Accepted Answer

Glycogen phosphorylase

Question 10

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

Accepted Answer

To produce NADPH and ribose-5-phosphate for biosynthetic reactions

Question 11

Which of the following statements about essential and non-essential amino acids is correct?

Accepted Answer

Essential amino acids must be obtained from the diet because the body cannot synthesize them.

Question 12

Cysteine is considered a unique amino acid because:

Accepted Answer

It contains a sulfur atom, allowing it to form disulfide bonds.

Question 13

Which of the following best describes the role of transamination in amino acid metabolism?

Accepted Answer

Transamination transfers an amino group from an amino acid to an alpha-keto acid, forming a new amino acid.

Question 14

A patient with a deficiency in the enzyme ornithine transcarbamylase would most likely have a buildup of which compound?

Accepted Answer

Carbamoyl phosphate

Question 15

Which cofactor is required for the transfer of one-carbon units in purine nucleotide biosynthesis?

Accepted Answer

Tetrahydrofolate (THF)

Question 16

Which of the following best explains why fatty acid oxidation generates more ATP per carbon than glucose oxidation?

Accepted Answer

Fatty acids are more reduced than glucose, allowing for more electron transfer to the electron transport chain.

Question 17

A patient with a genetic defect in carnitine transport would most likely have difficulty with which metabolic process?

Accepted Answer

Fatty acid oxidation

Question 18

Which of the following is a direct product of the urea cycle that is excreted from the body?

Accepted Answer

Urea

Question 19

Which of the following best describes the main goal of cellular metabolism?

Accepted Answer

To generate ATP for cellular processes

Question 20

A researcher is studying a new drug that increases the permeability of the inner mitochondrial membrane to protons. What is the most likely effect of this drug on ATP synthesis?

Accepted Answer

ATP synthesis will decrease because the proton gradient is dissipated.

Comprehensive Review of Core Metabolic Pathways in Biochemistry

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