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Biochemistry LE2

Total questions: 120

Worksheet time: 3600secs

Name
Class
Date
1.

Which enzyme complex irreversibly converts pyruvate to acetyl-CoA?

a)

Pyruvate dehydrogenase complex (PDH)

b)

Pyruvate carboxylase

c)

Lactate dehydrogenase

d)

Citrate synthase

2.

Which cofactor is not required by the PDH complex?

a)

Thiamine pyrophosphate (TPP)

b)

Biotin

c)

Lipoamide

d)

FAD

3.

PDH is activated by which of the following conditions?

a)

A. High NADH/NAD+ ratio

b)

B. High ADP concentrations

c)

C. High ATP concentrations

d)

D. Phosphorylation by PDH kinase

4.

The E1 subunit of PDH uses which cofactor?

a)

FAD

b)

TPP

c)

CoA

d)

NAD+

5.

Which enzyme regenerates lipoamide in the PDH complex?

a)

E1 (pyruvate dehydrogenase)

b)

E2 (dihydrolipoyl transacetylase)

c)

E3 (dihydrolipoyl dehydrogenase)

d)

Pyruvate carboxylase

6.

The first step of the TCA cycle is catalyzed by:

a)

Aconitase

b)

Citrate synthase

c)

Isocitrate dehydrogenase

d)

α-Ketoglutarate dehydrogenase

7.

Which TCA enzyme produces NADH directly?

a)

Succinate dehydrogenase

b)

Aconitase

c)

Isocitrate dehydrogenase

d)

Fumarase

8.

Which TCA intermediate is produced directly from α-ketoglutarate by oxidative decarboxylation?

a)

Succinyl-CoA

b)

Succinate

9.

Which TCA enzyme is located in the inner mitochondrial membrane and also participates in the ETC?

a)

Aconitase

b)

Succinate dehydrogenase (Complex II)

c)

Malate dehydrogenase

d)

α-Ketoglutarate dehydrogenase

10.

The net ATP (or ATP equivalents) yield per acetyl-CoA oxidized in TCA (through NADH/FADH₂ and GTP) is approximately:

a)

1 ATP

b)

3 ATP

c)

10 ATP equivalents

d)

30 ATP

11.

Which enzyme in the TCA cycle is regulated by substrate availability and by Ca²⁺ in muscle?

a)

Citrate synthase

b)

Isocitrate dehydrogenase

c)

Fumarase

d)

Malate dehydrogenase

12.

During anaplerosis, pyruvate carboxylase converts pyruvate to:

a)

A. Acetyl-CoA

b)

B. Oxaloacetate

c)

C. Citrate

d)

D. Malate

13.

Aconitase catalyzes conversion of citrate to:

a)

Isocitrate

b)

α-Ketoglutarate

c)

Succinate

d)

Oxaloacetate

14.

Which cofactor is required by α-ketoglutarate dehydrogenase (same as PDH E3 uses)?

a)

Biotin

b)

TPP

c)

Lipoic acid

d)

FAD

15.

Which complex of the electron transport chain accepts electrons from NADH?

a)

Complex II

b)

Complex I (NADH dehydrogenase)

c)

Complex III

d)

Complex IV

16.

The final electron acceptor of the ETC is:

a)

NAD+

b)

Oxygen

c)

FAD

d)

Cytochrome c

17.

Which complex pumps protons and transfers electrons from ubiquinol to cytochrome c?

a)

Complex I

b)

Complex II

c)

Complex III (cytochrome bc1)

d)

Complex IV

18.

ATP synthase couples proton flow back into the matrix to synthesize ATP. The F0 portion spans:

a)

The inner mitochondrial membrane

b)

The outer membrane

c)

The matrix

d)

The intermembrane space

19.

Which inhibitor blocks Complex IV (cytochrome c oxidase)?

a)

Rotenone

b)

Antimycin A

c)

Cyanide (CN−)

d)

Oligomycin

20.

Oligomycin inhibits which mitochondrial function?

a)

Complex I

b)

ATP synthase (F0)

c)

Complex III

d)

Uncoupling

21.

Uncouplers (e.g., 2,4-dinitrophenol) cause:

a)

Increased ATP synthesis

b)

Increased proton gradient

c)

Increased O2 consumption and decreased ATP production

d)

Inhibition of ETC complexes directly

22.

Which carrier transports electrons from Complex I/II to Complex III?

a)

Cytochrome c

b)

Ubiquinone (coenzyme Q)

c)

Flavoprotein

d)

ATP synthase

23.

The P/O ratio historically estimates ATP yield per oxygen atom reduced. Which pair approximates ATP from one NADH?

a)

~1.5 ATP

b)

~2.5 ATP

24.

Gluconeogenesis primarily occurs in which tissues?

a)

Brain and heart

b)

Liver and kidney cortex

c)

Skeletal muscle only

d)

Adipose tissue

25.

The irreversible enzyme that converts pyruvate to oxaloacetate in gluconeogenesis is:

a)

Pyruvate dehydrogenase

b)

Pyruvate carboxylase

c)

PEP carboxykinase

d)

Fructose-1,6-bisphosphatase

26.

PEP carboxykinase converts oxaloacetate to:

a)

Pyruvate

b)

Phosphoenolpyruvate (PEP)

c)

Citrate

d)

Fructose-6-phosphate

27.

Which enzyme is the key regulated step of gluconeogenesis opposing phosphofructokinase-1?

a)

Glucose-6-phosphatase

b)

Fructose-1,6-bisphosphatase

c)

Hexokinase

d)

Aldolase

28.

Substrates for gluconeogenesis include all EXCEPT:

a)

Lactate

b)

Glycerol

c)

Acetyl-CoA

d)

Alanine

29.

The main cellular location of glucose-6-phosphatase is:

a)

Cytosol

b)

Mitochondrial matrix

c)

Endoplasmic reticulum (ER) membrane

d)

Nucleus

30.

Which hormone stimulates gluconeogenesis?

a)

Insulin

b)

Glucagon

c)

Adiponectin

d)

AMP

31.

The uronic acid pathway (glucuronate pathway) produces which important metabolite?

(a)  

32.

Glucuronidation is important for:

a)

ATP synthesis

b)

Detoxification and conjugation of xenobiotics

c)

DNA replication

d)

Fatty acid β-oxidation

33.

Which sugar is the product that conjugates with bilirubin in the liver?

a)

Glucose

b)

UDP-glucuronic acid

c)

Galactose

d)

Mannose

34.

The HMP shunt / pentose phosphate pathway (PPP) provides cells with:

a)

ATP and GTP

b)

NADPH and ribose-5-phosphate

c)

FADH₂ and CoA

d)

Pyruvate and lactate

35.

The oxidative phase of PPP produces:

a)

Ribose-5-phosphate only

b)

NADPH and CO₂

c)

ATP

d)

Acetyl-CoA

36.

Which enzyme is the rate-limiting enzyme of the oxidative PPP?

a)

Transketolase

b)

Glucose-6-phosphate dehydrogenase (G6PD)

c)

6-phosphogluconate dehydrogenase

d)

Fructose-1,6-bisphosphatase

37.

A deficiency of G6PD leads to which clinical phenotype under oxidative stress?

a)

Megaloblastic anemia

b)

Hemolytic anemia

c)

Scurvy

d)

Osteoporosis

38.

The non-oxidative phase of PPP interconverts sugars using which cofactors/enzymes?

a)

Transketolase (requires TPP) and transaldolase

b)

Pyruvate kinase and hexokinase

c)

Glucokinase only

d)

Aldolase and enolase

39.

Cells that require high NADPH (for reductive biosynthesis) often use:

a)

Glycolysis exclusively

b)

PPP (oxidative branch)

40.

Lipids are broadly defined by which characteristic?

a)

Solubility in water

b)

Solubility in organic solvents and hydrophobicity

c)

High nitrogen content

d)

Being polymers of amino acids

41.

Which class of lipids contains a glycerol backbone esterified to fatty acids?

a)

Sphingolipids

b)

Glycerolipids (e.g., triacylglycerols)

c)

Sterols

d)

Glycosphingolipids

42.

Essential fatty acids in the human diet include:

a)

Palmitic acid only

b)

Oleic acid only

c)

Linoleic acid (omega-6) and α-linolenic acid (omega-3)

d)

Arachidonic acid only

43.

Which lipid is amphipathic and a major component of biological membranes?

a)

Triacylglycerol

b)

Cholesterol

c)

Phospholipids (e.g., phosphatidylcholine)

d)

Wax

44.

Cholesterol synthesis begins with which 2-carbon building block?

a)

Acetyl-CoA

b)

Pyruvate

c)

Malonyl-CoA

d)

Mevalonate

45.

Which of the following is NOT a prostanoid?

a)

Prostaglandin

b)

Prostacyclin (PGI₂)

c)

Leukotriene

d)

Thromboxane

46.

The enzyme cyclooxygenase (COX) converts arachidonic acid into:

a)

Leukotrienes

b)

Prostaglandin H₂ (PGH₂)

c)

Lipoxins

d)

LTB₄

47.

COX-1 vs COX-2: COX-2 is primarily:

a)

Constitutive in gastric mucosa

b)

Inducible during inflammation

c)

A mitochondrial enzyme

d)

Responsible for thromboxane production in platelets only

48.

Aspirin exerts its antiplatelet effect by acetylating and irreversibly inhibiting:

a)

5-lipoxygenase

b)

COX-1 in platelets

c)

COX-2 in endothelium

d)

Phospholipase A2

49.

Thromboxane A2 (TXA2) primarily causes:

a)

Vasodilation and inhibition of platelet aggregation

b)

Vasoconstriction and platelet aggregation

c)

Bronchodilation

d)

Increased cAMP in platelets

50.

Prostacyclin (PGI2) produced by endothelium causes:

a)

Platelet aggregation

b)

Vasoconstriction

c)

Vasodilation and inhibition of platelet aggregation

d)

Bronchoconstriction

51.

Leukotrienes are derived from arachidonic acid via which enzyme?

a)

Cyclooxygenase

b)

5-lipoxygenase (5-LOX)

c)

Thromboxane synthase

d)

Acetyl-CoA carboxylase

52.

Lipoxins generally have which effect in inflammation?

a)

Pro-inflammatory

b)

Anti-inflammatory and pro-resolution

c)

Cause fever only

d)

Stimulate leukotriene synthesis

53.

Fatty acids are classified by all EXCEPT:

a)

A. Chain length

b)

B. Degree of unsaturation

c)

C. Position of double bonds

d)

D. Presence of peptide bonds

54.

Which fatty acid is saturated?

a)

Oleic acid

b)

Palmitic acid

c)

Linoleic acid

d)

Arachidonic acid

55.

Which fatty acid is monounsaturated?

a)

Stearic acid

b)

Oleic acid (18:1 cis-9)

c)

Linoleic acid

d)

Palmitic acid

56.

Essential omega-3 fatty acid that can be converted (inefficiently) to EPA and DHA is:

a)

Alpha-linolenic acid (ALA)

b)

Linoleic acid

c)

Arachidonic acid

d)

Docosahexaenoic acid (DHA)

57.

Which of the following is an omega-3 fatty acid?

a)

Linoleic acid

b)

α-Linolenic acid (ALA)

c)

Arachidonic acid

d)

Palmitoleic acid

58.

Which lipid class serves mainly as long-term energy storage in adipose tissue?

a)

Phospholipids

b)

Triacylglycerols (TAGs)

c)

Glycolipids

d)

Sterols

59.

Glycerophospholipids have which head group attached to phosphatidic acid to make phosphatidylcholine?

a)

Serine

b)

Choline

c)

Sphingosine

d)

Glucose

60.

Sphingomyelin contains which backbone instead of glycerol?

a)

Glycerol-3-phosphate

b)

Sphingosine

c)

Cholesterol

d)

Ceramide only

61.

Glycolipids are primarily located on which side of the plasma membrane?

a)

Cytosolic leaflet

b)

Extracellular (outer) leaflet

c)

Inner mitochondrial membrane

d)

Nuclear envelope

62.

Which lipoprotein is the major carrier of dietary (exogenous) triacylglycerol?

a)

VLDL

b)

Chylomicrons

c)

LDL

d)

HDL

63.

Lipid digestion in the intestine requires which enzyme secreted by the pancreas?

a)

Lipoprotein lipase

b)

Pancreatic lipase

c)

Hormone sensitive lipase

d)

Glucoamylase

64.

Bile salts aid lipid absorption by:

a)

Hydrolyzing TAGs

b)

Emulsifying fats to form micelles

c)

Directly transporting lipids into enterocytes

d)

Inhibiting lipase

65.

Fatty acids are transported in blood primarily bound to:

(a)  

66.

Which of the following is the major carrier of free fatty acids in plasma?

a)

Serum albumin

b)

Chylomicrons only

c)

LDL particles only

67.

Fatty acid synthase (FAS) catalyzes de novo synthesis of palmitate using which 2-carbon donor?

a)

Malonyl-CoA (the 2-carbon plus CO₂ donor)

b)

Acetyl-CoA only

c)

Citrate

d)

Succinyl-CoA

68.

The rate-limiting enzyme for fatty acid synthesis is:

a)

Fatty acid synthase

b)

Acetyl-CoA carboxylase (ACC)

c)

Hormone sensitive lipase

d)

Carnitine palmitoyltransferase I

69.

Which cofactor is required for fatty acid synthase activity (reducing equivalents)?

a)

NADH

b)

NADPH

c)

FADH₂

d)

ATP only

70.

De novo palmitate synthesis occurs mainly in:

a)

Liver and adipose tissue

b)

Brain only

c)

Muscle only

d)

Kidney medulla only

71.

Regulation: Acetyl-CoA carboxylase (ACC) is activated by:

a)

AMPK phosphorylation

b)

Citrate and dephosphorylation

c)

Low insulin

d)

High glucagon

72.

Carnitine is required for which process?

a)

Fatty acid synthesis in cytosol

b)

Transport of long-chain fatty acyl-CoAs into mitochondria for β-oxidation

c)

Cholesterol esterification

d)

Bile acid synthesis

73.

In β-oxidation, each cycle shortens the fatty acyl-CoA by:

a)

1 carbon

b)

2 carbons (as acetyl-CoA)

c)

3 carbons

d)

4 carbons

74.

The mitochondrial enzyme that oxidizes succinate to fumarate and reduces FAD to FADH₂ is:

a)

Succinate dehydrogenase

b)

Fumarase

c)

Malate dehydrogenase

d)

Aconitase

75.

Succinate dehydrogenase

a)

Succinate dehydrogenase

b)

Succinate synthase

c)

Fumarase

d)

Malate dehydrogenase

76.

Odd-chain fatty acids produce which gluconeogenic precursor when fully oxidized?

a)

Acetyl-CoA only

b)

Propionyl-CoA → Succinyl-CoA (gluconeogenic)

c)

Butyryl-CoA only

d)

Acetoacetate

77.

Key enzyme for oxidation of very long chain fatty acids in peroxisomes is:

a)

Acyl-CoA oxidase

b)

Carnitine palmitoyltransferase I

c)

Hormone sensitive lipase

d)

Lipoprotein lipase

78.

Ketone bodies include all EXCEPT:

a)

A. Acetoacetate

b)

B. β-Hydroxybutyrate

c)

C. Acetone

d)

D. Oxaloacetate

79.

Ketogenesis occurs mainly in:

a)

Liver mitochondrial matrix

b)

Adipose tissue

c)

Brain

d)

Skeletal muscle

80.

Which enzyme catalyzes formation of HMG-CoA in cholesterol synthesis?

a)

HMG-CoA reductase

b)

HMG-CoA synthase (synthase forms HMG-CoA from acetoacetyl-CoA + acetyl-CoA; reductase reduces HMG-CoA to mevalonate)

c)

Squalene synthase

d)

Mevalonate kinase

81.

The committed, rate-limiting step in cholesterol biosynthesis is catalyzed by:

a)

HMG-CoA synthase

b)

HMG-CoA reductase

c)

Squalene synthase

d)

Mevalonate kinase

82.

Statins lower LDL cholesterol primarily by:

a)

Inhibiting intestinal cholesterol absorption

b)

Inhibiting HMG-CoA reductase and upregulating LDL receptors

c)

Increasing VLDL secretion

d)

Stimulating ACAT

83.

Cholesterol is a precursor for all EXCEPT:

a)

Bile acids

b)

Corticosteroid hormones

84.

Which lipoprotein is considered the major carrier of endogenous (hepatic) triglyceride to peripheral tissues?

a)

Chylomicron

b)

VLDL

c)

LDL

d)

HDL

85.

Lipoprotein lipase (LPL) is activated by which apoprotein on chylomicrons/VLDL?

a)

A. ApoB100

b)

B. ApoC-II

c)

C. ApoA-I

d)

D. ApoE

86.

The major apolipoprotein of LDL is:

a)

ApoA-I

b)

ApoB100

c)

ApoC-II

d)

ApoE

87.

Fatty acid β-oxidation yields reducing equivalents in the form of:

a)

NADH and FADH₂

b)

NADPH and FADH₂

c)

ATP directly

d)

NADP⁺ only

88.

In alcohol metabolism, ethanol is first oxidized to acetaldehyde by:

a)

Acetaldehyde dehydrogenase

b)

Alcohol dehydrogenase (ADH)

c)

Aldose reductase

d)

Cytochrome P450 2E1 only

89.

Acetaldehyde is further oxidized to acetate by:

a)

A. Aldehyde dehydrogenase (ALDH)

b)

B. Alcohol dehydrogenase

c)

C. Catalase

d)

D. Monoamine oxidase

90.

Chronic alcohol use induces which microsomal enzyme that contributes to ethanol oxidation?

a)

Glucose-6-phosphatase

b)

CYP2E1 (a cytochrome P450)

c)

Aldolase

d)

Succinate dehydrogenase

91.

A high NADH/NAD⁺ ratio from alcohol metabolism causes which metabolic effect?

a)

Inhibition of fatty acid synthesis

b)

Lactic acidosis and fatty liver (steatosis)

92.

Which enzyme catalyzes the committing condensation reaction in de novo fatty acid synthesis (formation of malonyl-CoA)?

a)

Acetyl-CoA carboxylase (ACC)

b)

Fatty acid synthase

c)

HMG-CoA reductase

d)

Carnitine palmitoyltransferase I

93.

Malonyl-CoA inhibits which enzyme to prevent simultaneous synthesis and oxidation of fatty acids?

a)

Acetyl-CoA carboxylase

b)

Carnitine palmitoyltransferase I (CPT1)

c)

Hormone sensitive lipase

d)

Fatty acid synthase

94.

During fasting, hormone sensitive lipase in adipose tissue is activated by:

a)

Insulin

b)

Glucagon and epinephrine via PKA phosphorylation

c)

High glucose concentration

d)

Malonyl-CoA

95.

Hormone sensitive lipase (HSL) hydrolyzes TAG to release:

a)

Cholesterol

b)

Fatty acids and glycerol

c)

Phospholipids

d)

Glucose

96.

Which enzyme in the liver converts glycerol to glycerol-3-phosphate for gluconeogenesis?

a)

Glycerol kinase

b)

Hormone sensitive lipase

c)

ALDH

d)

Lipoprotein lipase

97.

The primary transporter for long-chain acyl-CoA into mitochondria is:

a)

Acyl-CoA synthetase

b)

Carnitine palmitoyltransferase I (CPT1) on the outer mitochondrial membrane

c)

CPT2 on inner membrane only

d)

Fatty acid translocase

98.

Which metabolite from β-oxidation enters the TCA cycle directly?

a)

Propionyl-CoA

b)

Acetyl-CoA

c)

Succinyl-CoA only

d)

Malonyl-CoA

99.

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency leads to accumulation of:

a)

Long-chain fatty acids

b)

Medium-chain fatty acyl-carnitines and hypoketotic hypoglycemia

c)

Ketone bodies in excess only

d)

Uric acid

100.

Which ketone body can be measured in breath?

a)

Acetoacetate

b)

β-Hydroxybutyrate

c)

Acetone

d)

Succinyl-CoA

101.

Which of the following lipoproteins is primarily responsible for transporting cholesterol from the liver to peripheral tissues?

a)

VLDL (Very-Low-Density Lipoprotein)

b)

LDL (Low-Density Lipoprotein)

c)

HDL (High-Density Lipoprotein)

d)

Chylomicrons

102.

What is the primary function of the enzyme lipoprotein lipase?

a)

To synthesize triglycerides

b)

To convert cholesterol to bile acids

c)

To hydrolyze triglycerides in lipoproteins

d)

To transport fatty acids into cells

103.

Which metabolic pathway is primarily responsible for the synthesis of fatty acids?

a)

Citric acid cycle (TCA cycle)

b)

Fatty acid synthesis (lipogenesis)

c)

β-Oxidation

d)

Glycolysis

104.

Which molecule is produced during the conversion of succinyl-CoA to succinate in the TCA cycle?

a)

GTP

b)

FADH₂

c)

ATP

d)

NADH

105.

What is the primary function of the enzyme phosphofructokinase-1 (PFK-1) in glycolysis?

a)

Converts phosphoenolpyruvate to pyruvate

b)

Converts dihydroxyacetone phosphate to glyceraldehyde-3-phosphate

c)

Converts glucose to glucose-6-phosphate

d)

Converts fructose-6-phosphate to fructose-1,6-bisphosphate

106.

Which vitamin is a precursor for the coenzyme NAD+?

a)

Vitamin B6

b)

Vitamin B3

c)

Vitamin B2

d)

Vitamin B1

107.

Which enzyme is responsible for converting isocitrate to α-ketoglutarate in the TCA cycle?

a)

A. Isocitrate dehydrogenase

b)

B. Aconitase

c)

C. Succinate dehydrogenase

d)

D. Malate dehydrogenase

108.

What is the primary function of the enzyme lipoprotein lipase?

a)

D. Regulate glucose metabolism

b)

C. Convert fatty acids to acyl-CoA

c)

B. Synthesize cholesterol

d)

A. Hydrolyze triglycerides in lipoproteins

109.

Which vitamin is a cofactor for the enzyme pyruvate carboxylase?

a)

D. Vitamin B6 (Pyridoxine)

b)

A. Vitamin B1 (Thiamine)

c)

B. Vitamin B7 (Biotin)

d)

C. Vitamin B2 (Riboflavin)

110.

What is the primary function of the pentose phosphate pathway?

a)

ATP production

b)

NADPH production

c)

Fatty acid synthesis

d)

Protein synthesis

111.

Which molecule is produced during the conversion of isocitrate to α-ketoglutarate in the TCA cycle?

a)

CO₂

b)

NADH

c)

FADH₂

d)

ATP

112.

Which of the following statements about fatty acid configuration is most accurate?

a)

Naturally occurring unsaturated fatty acids are predominantly in the trans configuration.

b)

Cis double bonds in fatty acids increase melting point and allow tight packing.

c)

Cis double bonds introduce kinks that decrease van der Waals interactions, lowering melting point.

d)

Trans fatty acids are produced by enzymatic desaturation in humans.

113.

Which of the following lipids serves as both a structural membrane component and a precursor for intracellular signaling molecules?

a)

Triacylglycerol

b)

Phosphatidylinositol 4,5-bisphosphate

c)

Cholesteryl ester

d)

Ceramide

114.

Which of the following best differentiates sphingolipids from glycerophospholipids?

a)

Sphingolipids contain phosphoric acid residues.

b)

Sphingolipids have glycerol as their backbone.

c)

Sphingolipids contain an amide-linked fatty acid to a sphingoid base.

d)

Sphingolipids are always neutral and nonpolar.

115.

Which of the following correctly identifies a lipid derived from arachidonic acid metabolism?

a)

Sphingomyelin

b)

Prostaglandin E₂

c)

Cholesteryl oleate

d)

Phosphatidylcholine

116.

Which of the following statements about lipoprotein lipid composition is correct?

a)

HDL contains the highest proportion of triacylglycerols.

b)

LDL has a higher protein-to-lipid ratio than HDL.

c)

VLDL transports cholesterol from tissues to the liver.

d)

HDL contains the highest proportion of protein relative to lipids.

117.

Which property of cholesterol is essential for maintaining membrane fluidity at physiological temperatures?

a)

Its polar head interacts with fatty acid chains.

b)

Its rigid ring structure disrupts packing of phospholipid tails.

c)

Its esterified hydroxyl group enhances flexibility.

d)

Its hydrocarbon tail increases membrane permeability.

118.

Which of the following best describes the coordinated regulation between fatty acid oxidation and synthesis?

a)

Increased NADH levels activate β-oxidation and inhibit lipogenesis by stimulating ACC.

b)

Malonyl-CoA inhibits carnitine palmitoyltransferase I, preventing simultaneous oxidation and synthesis.

c)

Fatty acid synthesis is favored when the AMP/ATP ratio is high due to AMPK activation.

d)

β-oxidation and lipogenesis occur simultaneously under high insulin conditions.

119.

During prolonged fasting, hepatic β-oxidation supports gluconeogenesis primarily by which of the following mechanisms?

a)

Supplying acetyl-CoA as a direct carbon source for glucose synthesis.

b)

Providing NADH and ATP required for gluconeogenic reactions.

c)

Increasing cytosolic citrate, which activates phosphofructokinase-1.

d)

Decreasing mitochondrial acetyl-CoA concentration, thereby activating pyruvate dehydrogenase.

120.

Which of the following accurately describes the metabolic fate of odd-chain fatty acids during β-oxidation?

a)

They yield only acetyl-CoA units throughout oxidation.

b)

Propionyl-CoA is converted to succinyl-CoA via a biotin- and vitamin B₁₂–dependent pathway.

c)

Propionyl-CoA directly enters glycolysis as pyruvate.

d)

They cannot be oxidized in humans.

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Câu hỏi trắc nghiệm về Dinh dưỡng | Worksheet

quiz

Worksheet

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