About this Study Set
This study set covers Biochemistry through
15 practice questions.
A challenging examination of human metabolic pathways, enzymatic functions, and physiological chemical regulation. Every question includes the correct answer so you can learn as you go — pick any format above to get started.
Questions & Answers
Browse all 15 questions from the
Advanced Human Biochemistry study set below.
Each question shows the correct answer — select a study format above to practice interactively.
1
Which specific complex in the electron transport chain does cyanide inhibit, effectively ceasing aerobic cellular respiration?
-
A
Complex I (NADH dehydrogenase)
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B
Complex II (Succinate dehydrogenase)
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C
Complex III (Cytochrome c reductase)
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D
Complex IV (Cytochrome c oxidase)
2
In the urea cycle, which molecule acts as the primary nitrogen donor for the synthesis of citrulline from ornithine?
-
A
Aspartate
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B
Carbamoyl phosphate
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C
Argininosuccinate
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D
Glutamate
3
Which amino acid is the primary precursor for the synthesis of the neurotransmitter serotonin in the human central nervous system?
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A
Tyrosine
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B
Tryptophan
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C
Phenylalanine
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D
Histidine
4
During gluconeogenesis, which enzyme is responsible for the bypass of the pyruvate kinase step by converting pyruvate into oxaloacetate?
-
A
Pyruvate carboxylase
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B
Phosphoenolpyruvate carboxykinase
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C
Fructose-1,6-bisphosphatase
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D
Glucose-6-phosphatase
5
What is the rate-limiting enzyme in the cholesterol biosynthesis pathway, which is the target of statin medications?
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A
Squalene synthase
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B
HMG-CoA reductase
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C
Mevalonate kinase
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D
Acetyl-CoA acetyltransferase
6
Which form of vitamin K is required as a cofactor for the gamma-carboxylation of glutamic acid residues in blood clotting factors?
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A
Phylloquinone
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B
Menaquinone
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C
Menadione
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D
Hydroquinone
7
Which metabolic intermediate is common to both the citric acid cycle and the urea cycle?
-
A
Fumarate
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B
Alpha-ketoglutarate
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C
Succinyl-CoA
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D
Oxaloacetate
8
In the pentose phosphate pathway, which enzyme is responsible for the rate-limiting step that produces NADPH?
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A
6-phosphogluconate dehydrogenase
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B
Glucose-6-phosphate dehydrogenase
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C
Transketolase
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D
Transaldolase
9
The Bohr effect describes the rightward shift of the oxygen-hemoglobin dissociation curve in response to which conditions?
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A
Increased pH and decreased CO2
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B
Decreased pH and increased CO2
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C
Increased pH and increased 2,3-BPG
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D
Decreased pH and decreased CO2
10
Which human enzyme is primarily responsible for the detoxification of reactive oxygen species by converting superoxide radicals into hydrogen peroxide?
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A
Catalase
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B
Glutathione peroxidase
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C
Superoxide dismutase
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D
Peroxiredoxin
11
Which biochemical feature characterizes the structure of the human insulin receptor?
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A
G-protein coupled receptor
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B
Nuclear hormone receptor
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C
Receptor tyrosine kinase
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D
Ligand-gated ion channel
12
During prolonged starvation, what is the primary source of carbon for gluconeogenesis in the human liver?
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A
Glycerol from adipose tissue
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B
Alanine from skeletal muscle
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C
Glycogen from muscle
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D
Dietary fructose
13
Which enzyme is deficient in patients with Phenylketonuria (PKU), preventing the conversion of phenylalanine to tyrosine?
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A
Phenylalanine hydroxylase
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B
Tyrosinase
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C
Phenylalanine transaminase
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D
Homogentisate 1,2-dioxygenase
14
In the beta-oxidation of odd-chain fatty acids, the final cleavage produces acetyl-CoA and which other molecule?
-
A
Malonyl-CoA
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B
Propionyl-CoA
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C
Succinyl-CoA
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D
Acetoacetyl-CoA
15
Which iron-sulfur cluster protein is essential for the mitochondrial synthesis of heme groups?
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A
Ferrochelatase
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B
Aconitase
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C
Succinate dehydrogenase
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D
Cytochrome b
