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Krebs Cycle and Transport Mechanisms Quiz

Total questions: 61

Worksheet time: 46mins

Name
Class
Date
1.

Which of the following enzymes in the Krebs cycle catalyzes a substrate-level phosphorylation reaction?

a)

Aconitase

b)

Isocitrate dehydrogenase

c)

α-Ketoglutarate dehydrogenase

d)

Succinyl-CoA synthetase

e)

Fumarase

2.

Which of the following statements about the Krebs cycle is TRUE?

a)

It occurs in the cytosol

b)

It produces 4 molecules of NADH per cycle

c)

It is the primary site of oxidative phosphorylation

d)

It directly generates ATP via oxidative phosphorylation

e)

It supplies intermediates for amino acid synthesis

3.

Fluoroacetate is a metabolic poison that inhibits the Krebs cycle by blocking which enzyme?

a)

Citrate synthase

b)

Aconitase

c)

Isocitrate dehydrogenase

d)

Succinate dehydrogenase

e)

Malate dehydrogenase

4.

Which of the following is NOT a product of one turn of the Krebs cycle?

a)

NADH

b)

FADH₂

c)

ATP

d)

Oxygen

e)

Carbon dioxide

5.

Which coenzyme is required for the α-ketoglutarate dehydrogenase complex in the Krebs cycle?

a)

NADP+

b)

Coenzyme A

c)

Biotin

d)

Pyridoxal phosphate

e)

Tetrahydrofolate

6.

All of the following enzymes are involved in the Krebs cycle EXCEPT:

a)

Citrate synthase

b)

Pyruvate dehydrogenase

c)

Isocitrate dehydrogenase

d)

Malate dehydrogenase

e)

Fumarase

7.

Which of the following reactions in the Krebs cycle generates FADH₂?

a)

Isocitrate → α-ketoglutarate

b)

α-Ketoglutarate → Succinyl-CoA

c)

Succinate → Fumarate

d)

Fumarate → Malate

e)

Malate → Oxaloacetate

8.

Which enzyme catalyzes the first committed step of the Krebs cycle?

a)

Citrate synthase

b)

Isocitrate dehydrogenase

c)

Aconitase

d)

Succinyl-CoA synthetase

e)

Malate dehydrogenase

9.

The conversion of malate to oxaloacetate is an oxidation reaction that produces which molecule?

a)

NADH

b)

FADH₂

c)

ATP

d)

GTP

e)

CO₂

10.

Which of the following is the correct sequence of intermediates in the Krebs cycle?

a)

Acetyl-CoA → Citrate → Isocitrate → α-Ketoglutarate → Succinyl-CoA → Succinate → Fumarate → Malate → Oxaloacetate

b)

Acetyl-CoA → Citrate → α-Ketoglutarate → Isocitrate → Succinyl-CoA → Succinate → Malate → Fumarate → Oxaloacetate

c)

Acetyl-CoA → Citrate → Succinyl-CoA → Isocitrate → α-Ketoglutarate → Fumarate → Succinate → Malate → Oxaloacetate

d)

Acetyl-CoA → Citrate → Isocitrate → Succinate → α-Ketoglutarate → Succinyl-CoA → Fumarate → Malate → Oxaloacetate

e)

Acetyl-CoA → Citrate → Isocitrate → α-Ketoglutarate → Succinate → Succinyl-CoA → Fumarate → Malate → Oxaloacetate

11.

A deficiency in which vitamin would most directly affect the function of α-ketoglutarate dehydrogenase?

a)

Vitamin A

b)

Vitamin B₁ (Thiamine)

c)

Vitamin C

d)

Vitamin E

e)

Vitamin K

12.

Which molecule provides the two-carbon unit that enters the Krebs cycle?

a)

Pyruvate

b)

Acetyl-CoA

c)

Oxaloacetate

d)

Citrate

e)

Fumarate

13.

Which enzyme in the Krebs cycle is embedded in the inner mitochondrial membrane and also participates in the electron transport chain?

a)

Succinate dehydrogenase

b)

Aconitase

c)

Isocitrate dehydrogenase

d)

Fumarase

e)

Citrate synthase

14.

How many molecules of CO₂ are released per turn of the Krebs cycle?

a)

1

b)

2

c)

3

d)

4

e)

0

15.

Which of the following intermediates of the Krebs cycle is an important precursor for heme synthesis?

a)

α-Ketoglutarate

b)

Oxaloacetate

c)

Fumarate

d)

Succinyl-CoA

e)

Malate

16.

Which step in the Krebs cycle is directly coupled to GTP synthesis?

a)

Citrate → Isocitrate

b)

α-Ketoglutarate → Succinyl-CoA

c)

Succinyl-CoA → Succinate

d)

Fumarate → Malate

e)

Malate → Oxaloacetate

17.

Which of the following statements about the regulation of the Krebs cycle is CORRECT?

a)

ATP stimulates isocitrate dehydrogenase

b)

NADH inhibits α-ketoglutarate dehydrogenase

c)

ADP inhibits citrate synthase

d)

Succinyl-CoA activates α-ketoglutarate dehydrogenase

e)

FADH₂ inhibits succinate dehydrogenase

18.

Which enzyme catalyzes the formation of a six-carbon molecule in the Krebs cycle?

a)

Citrate synthase

b)

Aconitase

c)

Isocitrate dehydrogenase

d)

α-Ketoglutarate dehydrogenase

e)

Succinyl-CoA synthetase

19.

What is the primary function of the Krebs cycle?

a)

To generate large amounts of ATP

b)

To provide precursors for anabolic pathways

c)

To directly transport electrons to oxygen

d)

To store excess glucose

e)

To break down fatty acids

20.

Which of the following is NOT an anaplerotic reaction that replenishes intermediates of the Krebs cycle?

a)

Pyruvate → Oxaloacetate

b)

Aspartate → Oxaloacetate

c)

Glutamate → α-Ketoglutarate

d)

Succinate → Fumarate

e)

Propionyl-CoA → Succinyl-CoA

21.

Which of the following statements about endocytosis is CORRECT?

a)

It only occurs in specialized cells like phagocytes.

b)

Clathrin-coated vesicles are involved in receptor-mediated endocytosis.

c)

Pinocytosis is a form of exocytosis.

d)

Endocytosis is primarily used for secreting proteins.

e)

It is an energy-independent process.

22.

Exocytosis is essential for all the following EXCEPT:

a)

Neurotransmitter release

b)

Secretion of insulin

c)

Degradation of engulfed bacteria

d)

Transport of vesicles to the plasma membrane

e)

Export of large molecules

23.

The primary role of SNARE proteins in exocytosis is to:

a)

Hydrolyze ATP for vesicle fusion

b)

Bind to clathrin for vesicle formation

c)

Facilitate docking and membrane fusion

d)

Act as ion channels for calcium influx

e)

Mediate receptor endocytosis

24.

The low pH in early endosomes facilitates:

a)

The release of ligands from receptors

b)

Fusion with lysosomes

c)

ATP synthesis

d)

Protein synthesis

e)

Membrane depolarization

25.

Which of the following receptors is NOT primarily internalized via receptor-mediated endocytosis?

a)

LDL receptor

b)

Insulin receptor

c)

Transferrin receptor

d)

Epidermal growth factor receptor

e)

Vitamin B12-intrinsic factor receptor

26.

Clathrin-coated pits are directly involved in:

a)

Endoplasmic reticulum protein trafficking

b)

Exocytosis of neurotransmitters

c)

Receptor-mediated endocytosis

d)

Non-specific pinocytosis

e)

Formation of nuclear pores

27.

A patient with familial hypercholesterolemia has a mutation in the LDL receptor gene. This results in:

a)

Increased cholesterol uptake

b)

Impaired LDL endocytosis

c)

Increased bile acid synthesis

d)

Increased HDL clearance

e)

Increased LDL degradation

28.

Which glucose transporter is insulin-dependent?

a)

GLUT1

b)

GLUT2

c)

GLUT3

d)

GLUT4

e)

GLUT5

29.

GLUT2 is found in all the following tissues EXCEPT:

a)

Liver

b)

Pancreatic β-cells

c)

Small intestine

d)

Red blood cells

e)

Kidney

30.

The primary glucose transporter in the brain is:

a)

GLUT1

b)

GLUT2

c)

GLUT3

d)

GLUT4

e)

GLUT5

31.

The primary glucose transporter in the brain is:

a)

GLUT1

b)

GLUT2

c)

GLUT3

d)

GLUT4

e)

GLUT5

32.

Fructose is primarily transported into cells by:

a)

GLUT1

b)

GLUT2

c)

GLUT3

d)

GLUT4

e)

GLUT5

33.

Which statement regarding GLUT transporters is FALSE?

a)

GLUT1 is involved in basal glucose uptake

b)

GLUT2 functions as a bidirectional transporter

c)

GLUT3 has the highest affinity for glucose

d)

GLUT4 is constitutively present on muscle cell membranes

e)

GLUT5 primarily transports fructose

34.

Which of the following ion channels is voltage-gated?

a)

Nicotinic acetylcholine receptor

b)

ATP-sensitive potassium channel

c)

CFTR chloride channel

d)

Voltage-gated sodium channel

e)

Aquaporins

35.

Ligand-gated ion channels are activated by:

a)

ATP hydrolysis

b)

Membrane depolarization

c)

Direct binding of neurotransmitters

d)

Osmotic pressure

e)

Mechanical stretching of the membrane

36.

Ion selectivity in ion channels is primarily determined by:

a)

ATP hydrolysis

b)

The charge and size of the ion

c)

The presence of SNARE proteins

d)

The lipid bilayer

e)

The availability of sodium

37.

The Na+/K+ ATPase pump moves:

a)

3 Na+ in, 2 K+ out

b)

2 Na+ in, 3 K+ out

c)

3 Na+ out, 2 K+ in

d)

1 Na+ out, 1 K+ in

e)

4 Na+ out, 4 K+ in

38.

Which statement about ion channels is TRUE?

a)

They always require ATP for function

b)

They transport ions against their gradient

c)

They allow the rapid and selective movement of ions

d)

They only function in neurons

e)

They are impermeable to water

39.

The cystic fibrosis transmembrane conductance regulator (CFTR) is:

a)

A voltage-gated sodium channel

b)

A potassium channel

c)

A chloride ion channel

d)

A calcium ion channel

e)

A glucose transporter

40.

The primary role of calcium ion channels in neurons is to:

a)

Initiate the action potential

b)

Stimulate vesicle fusion for neurotransmitter release

c)

Act as secondary messengers

d)

Increase sodium permeability

e)

Maintain resting membrane potential

41.

Which of the following best describes aquaporins?

a)

They are voltage-gated

b)

They allow passive water transport

c)

They hydrolyze ATP for active transport

d)

They co-transport glucose and sodium

e)

They transport ions and water

42.

Which class of enzymes is most commonly used in detergent formulations to break down protein stains?

a)

Amylases

b)

Proteases

c)

Lipases

d)

Cellulases

e)

Oxidases

43.

Which of the following is NOT a common enzyme found in modern laundry detergents?

a)

Lipase

b)

Protease

c)

Amylase

d)

Dehydrogenase

e)

Cellulase

44.

Lipases are added to detergents to hydrolyze which of the following components in stains?

a)

Starch

b)

Proteins

c)

Lipids

d)

Nucleic acids

e)

Phosphates

45.

The enzyme alkaline protease used in detergents is most commonly derived from which microorganism?

a)

Bacillus subtilis

b)

Escherichia coli

c)

Saccharomyces cerevisiae

d)

Pseudomonas aeruginosa

e)

Aspergillus niger

46.

Which statement about detergent enzymes is INCORRECT?

a)

They work best at specific pH and temperature conditions

b)

They can be denatured by harsh chemicals

c)

Proteases help remove fat-based stains

d)

Lipases target grease and oil stains

e)

Amylases help break down starch residues

47.

Which enzyme is commonly used in the brewing industry to convert starch into fermentable sugars?

a)

Cellulase

b)

Protease

c)

α-Amylase

d)

Lipase

e)

Ligase

48.

All of the following enzymes are used in cheese production EXCEPT:

a)

Rennet

b)

Protease

c)

Lipase

d)

Urease

e)

Chymosin

49.

Which microorganism is widely used for the production of citric acid in food biotechnology?

a)

Penicillium notatum

b)

Aspergillus niger

c)

Escherichia coli

d)

Bacillus subtilis

e)

Saccharomyces cerevisiae

50.

Invertase is an important enzyme in food processing because it:

a)

Breaks down proteins

b)

Hydrolyzes sucrose into glucose and fructose

c)

Converts lactose into glucose and galactose

d)

Transforms starch into maltose

e)

Facilitates the coagulation of milk

51.

Which statement about food biotechnology enzymes is INCORRECT?

a)

Pectinases are used to clarify fruit juices

b)

Lipases are used in cheese ripening

c)

Proteases help tenderize meat

d)

DNA polymerase is used in cheese production

e)

Amylases break down starch into maltose

52.

Which enzyme is commonly used in bioremediation to break down oil spills?

a)

Amylase

b)

Protease

c)

Lipase

d)

Urease

e)

Cellulase

53.

Which of the following bacteria is often used in biodegradation of plastics?

a)

Bacillus subtilis

b)

Pseudomonas putida

c)

Escherichia coli

d)

Saccharomyces cerevisiae

e)

Clostridium botulinum

54.

Laccases, used in environmental biotechnology, are primarily involved in:

a)

Degrading lignin and phenolic compounds

b)

Hydrolyzing starch into glucose

c)

Breaking down lipid molecules

d)

Synthesizing biodegradable plastics

e)

Facilitating protein digestion

55.

Which of the following enzymes is commonly used in the treatment of industrial wastewater?

a)

Cellulase

b)

Protease

c)

Amylase

d)

Peroxidase

e)

Phosphatase

56.

Which of the following is NOT a function of microbial enzymes in environmental applications?

a)

Degrading pesticides

b)

Digesting plastic materials

c)

Breaking down oil spills

d)

Synthesizing antibiotics

e)

Removing heavy metal contaminants

57.

Which of the following enzymes is widely used in biofuel production?

a)

Lipase

b)

Cellulase

c)

Protease

d)

Ligase

e)

Oxidase

58.

Which microorganism is commonly used in the production of bioethanol from agricultural waste?

a)

Bacillus subtilis

b)

Aspergillus flavus

c)

Saccharomyces cerevisiae

d)

Escherichia coli

e)

Clostridium tetani

59.

Which statement about enzyme immobilization in biotechnology is FALSE?

a)

It enhances enzyme stability

b)

It allows enzyme reuse

c)

It increases contamination risks

d)

It can involve adsorption on solid supports

e)

It is commonly used in industrial processes

60.

Which enzyme is used in the paper and textile industry for bleaching purposes?

a)

Lipase

b)

Peroxidase

c)

Protease

d)

Cellulase

e)

Amylase

61.

Which enzyme is used in the breakdown of urea in wastewater treatment?

a)

Lipase

b)

Cellulase

c)

Urease

d)

Catalase

e)

Peroxidase

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