Free Radical And Oxygen Toxicity

Question 1

Which label correctly identifies the primary site of superoxide generation in the mitochondrion?
[Insert diagram of mitochondrion with labeled complexes I-IV]

Answer 1

A. Complex I
B. Complex II
C. Complex III
D. Complex IV
Correct Answer: A

Question 2

Identify the phase of lipid peroxidation shown in the diagram:
[Insert diagram showing initiation, propagation, and termination]

Answer 2

A. Initiation
B. Propagation
C. Termination
D. Recovery
Correct Answer: B

Question 3

Which component in this antioxidant pathway is responsible for converting superoxide into hydrogen peroxide?
[Insert antioxidant enzyme pathway diagram]

Answer 3

A. Catalase
B. Glutathione peroxidase
C. Superoxide dismutase (SOD)
D. Peroxidase
Correct Answer: C

Question 4

Which structure is the primary cellular source of ROS in the image below?
[Insert labeled cell diagram with nucleus, mitochondria, peroxisomes, lysosomes]

Answer 4

A. Lysosome
B. Peroxisome
C. Mitochondrion
D. Nucleus
Correct Answer: C

Question 5

From the diagram, which step leads to the accumulation of lipid peroxides?
[Insert lipid peroxidation mechanism image with chain reactions]

Answer 5

A. Radical abstraction
B. Oxygen addition
C. Propagation
D. Accumulation
Correct Answer: D

Question 6

Which of the following defines a free radical?

Answer 6

A. A molecule with all electrons paired
B. A molecule that donates protons
C. A species with one or more unpaired electrons
D. A molecule that loses oxygen
Correct Answer: C

Question 7

What is the role of antioxidants in the body?

Answer 7

A. Generate free radicals
B. Pair with oxygen
C. Donate electrons to stabilize free radicals
D. Degrade proteins
Correct Answer: C

Question 8

Which of the following is an example of a reactive oxygen species (ROS)?

Answer 8

A. CO2
B. O2*−
C. CH4
D. NH3
Correct Answer: B

Question 9

Which organelle contributes most significantly to ROS production during aerobic respiration?

Answer 9

A. Lysosome
B. Endoplasmic reticulum
C. Golgi apparatus
D. Mitochondrion
Correct Answer: D

Question 10

Which vitamin functions as a non-enzymatic antioxidant?

Answer 10

A. Vitamin K
B. Vitamin C
C. Vitamin B6
D. Vitamin D
Correct Answer: B

Question 11

Assertion: Free radicals are involved in the aging process.
Reason: Free radicals cause cellular damage including DNA mutations and lipid peroxidation.

Answer 11

A. Both A and R are true, and R explains A.
B. Both A and R are true, but R does not explain A.
C. A is true, R is false.
D. A is false, R is true.
Correct Answer: A

Question 12

Assertion: Antioxidants only function inside the cell.
Reason: Alpha-tocopherol is an antioxidant found only in intracellular spaces.

Answer 12

A. Both A and R are true, and R explains A.
B. Both A and R are true, but R does not explain A.
C. A is true, R is false.
D. A is false, R is true.
Correct Answer: D

Question 13

Assertion: Hydrogen peroxide is a reactive oxygen species.
Reason: It is formed by the enzymatic activity of catalase.

Answer 13

A. Both A and R are true, and R explains A.
B. Both A and R are true, but R does not explain A.
C. A is true, R is false.
D. A is false, R is true.
Correct Answer: C

Question 14

Assertion: Lipid peroxidation only occurs in prokaryotes.
Reason: Prokaryotes have mitochondria that generate ROS.

Answer 14

A. Both A and R are true, and R explains A.
B. Both A and R are true, but R does not explain A.
C. A is true, R is false.
D. A is false, R is true.
Correct Answer: D

Question 15

Assertion: Mitochondria are a significant source of superoxide radicals.
Reason: Electrons may leak from the electron transport chain and react with oxygen.

Answer 15

A. Both A and R are true, and R explains A.
B. Both A and R are true, but R does not explain A.
C. A is true, R is false.
D. A is false, R is true.
Correct Answer: A

Question 16

Free radicals have paired electrons.

Answer 16

False

Question 17

Superoxide dismutase (SOD) converts superoxide to hydrogen peroxide.

Answer 17

True

Question 18

Free radicals can be generated from external sources like radiation.

Answer 18

True

Question 19

Catalase converts hydrogen peroxide into water and oxygen.

Answer 19

True

Question 20

Lipid peroxidation stabilizes cellular membranes.

Answer 20

False

Question 21

Hydroxyl radicals are the least reactive ROS.

Answer 21

False

Question 22

Vitamin E is a non-enzymatic antioxidant found in the lipid phase.

Answer 22

True

Question 23

Mitochondria are not involved in the production of ROS.

Answer 23

False

Question 24

Exercise may increase ROS production in cells.

Answer 24

True

Question 25

Glutathione peroxidase uses NADPH to reduce hydrogen peroxide.

Answer 25

False

Question 27

Front

Answer 27

Back

Question 28

Identify the free radical involved in site-specific oxidative DNA damage in the copper/H2O2 system. [Insert diagram of copper-mediated Fenton reaction near DNA]

Answer 28

A. Superoxide B. Singlet oxygen C. Hydroxyl radical D. Nitric oxide Correct Answer: C

Question 29

Which zone in the transplant organ diagram is most prone to ischemia-reperfusion ROS damage? [Insert transplant tissue diagram with zones]

Answer 29

A. Outer cortex B. Medullary core C. Perivascular zone D. Reperfusion edge Correct Answer: D

Question 30

From this antioxidant enzyme chart, which enzyme detoxifies lipid peroxides? [Insert enzyme functions table]

Answer 30

A. Catalase B. Glutathione reductase C. Glutathione peroxidase D. SOD Correct Answer: C

Question 31

Based on the mechanism diagram, what is the first reactive product when ROS attack polyunsaturated fatty acids? [Insert lipid peroxidation chain reaction diagram]

Answer 31

A. Alcohol B. Peroxyl radical C. Ketone D. Aldehyde Correct Answer: B

Question 32

In this pathway diagram of NF-κB activation, what triggers its translocation during oxidative stress? [Insert pathway image with IκB degradation step]

Answer 32

A. Protein kinase inhibition B. IκB degradation C. Direct DNA binding D. ROS depletion Correct Answer: B

Question 33

Which of the following enzymes directly contributes to ischemia-reperfusion injury in myocardial tissue?

Answer 33

A. Glutathione reductase B. Superoxide dismutase C. Xanthine oxidase D. Nitric oxide synthase Correct Answer: C

Question 34

Which antioxidant system functions both intracellularly and extracellularly?

Answer 34

A. SOD B. Alpha-tocopherol C. Catalase D. Glutathione Correct Answer: B

Question 35

Which reactive oxygen species is generated from NADPH oxidase in phagocytes?

Answer 35

A. Hydrogen peroxide B. Hydroxyl radical C. Superoxide D. Nitric oxide Correct Answer: C

Question 36

Which dietary antioxidant is most effective at scavenging peroxyl radicals in lipid membranes?

Answer 36

A. Vitamin B1 B. Vitamin E C. Vitamin C D. Glutathione Correct Answer: B

Question 37

What is the role of ceruloplasmin in oxidative stress defense?

Answer 37

A. Transfers copper to DNA B. Binds iron to prevent ROS generation C. Scavenges hydrogen peroxide D. Carries oxygen in blood Correct Answer: B

Question 38

Assertion: Antioxidant enzymes require trace elements for optimal function. Reason: Selenium is needed for GPx and zinc/copper for SOD activity.

Answer 38

A. Both A and R are true, and R explains A. Correct Answer: A

Question 39

Assertion: Vitamin E can reverse lipid peroxidation. Reason: It interrupts propagation by donating hydrogen to lipid peroxyl radicals.

Answer 39

A. Both A and R are true, and R explains A. Correct Answer: A

Question 40

Assertion: Free radicals promote carcinogenesis. Reason: Oxidative DNA damage can activate oncogenes or inhibit tumor suppressor genes.

Answer 40

A. Both A and R are true, and R explains A. Correct Answer: A

Question 41

Assertion: Catalase detoxifies singlet oxygen. Reason: Catalase catalyzes conversion of hydrogen peroxide to water and oxygen.

Answer 41

C. A is true, R is false. Correct Answer: C

Question 42

Assertion: ROS generation can enhance HIV replication. Reason: ROS activate NF-κB, which upregulates HIV transcription.

Answer 42

A. Both A and R are true, and R explains A. Correct Answer: A

Question 43

Alpha-tocopherol is water-soluble and acts in cytosol.

Answer 43

False

Question 44

Allopurinol inhibits xanthine oxidase to reduce oxidative injury.

Answer 44

True

Question 45

Ischemia alone causes more oxidative damage than reperfusion.

Answer 45

False

Question 46

ROS can promote viral gene expression in infected lymphocytes.

Answer 46

True

Question 47

Peroxyl radicals are detoxified by catalase.

Answer 47

False

Question 48

8-oxoguanine is a mutagenic lesion in DNA caused by ROS.

Answer 48

True

Question 49

SOD is an effective scavenger of hydroxyl radicals.

Answer 49

False

Question 50

ROS contribute to endothelial injury in atherosclerosis.

Answer 50

True

Question 51

Glutathione reductase uses NADPH to regenerate reduced GSH.

Answer 51

True

Question 52

ROS play no role in neurodegenerative diseases.

Answer 52

False

Question 53

Front

Answer 53

Back

Question 54

Which label on the diagram corresponds to the site of ROS generation during ischemia-reperfusion? [Insert diagram of tissue with ischemic and reperfusion zones labeled]

Answer 54

A. Ischemic zone B. Reperfused zone C. Necrotic core D. Endothelial boundary Correct Answer: B

Question 55

Identify the enzyme responsible for hydrogen peroxide breakdown in the diagram of antioxidant defenses. [Insert enzyme pathway showing SOD, catalase, GPx]

Answer 55

A. Superoxide dismutase B. Glutathione reductase C. Catalase D. Lipase Correct Answer: C

Question 56

What step in the chain reaction is shown in this lipid peroxidation diagram? [Insert diagram showing fatty acid radical reacting with O2]

Answer 56

A. Termination B. Chain propagation C. Antioxidant rescue D. Initiation Correct Answer: B

Question 57

From the diagram of copper-mediated ROS generation, what is the product of H2O2 and Cu+? [Insert ROS generation pathway]

Answer 57

A. O2*− B. OH* C. NO* D. H2O Correct Answer: B

Question 58

What damage outcome is highlighted in this DNA damage diagram? [Insert labeled DNA with 8-oxoguanine lesion and strand breaks]

Answer 58

A. Point mutation B. Strand breakage C. Protein oxidation D. Membrane leakage Correct Answer: B

Question 59

Which reactive oxygen species is most associated with DNA strand breakage?

Answer 59

A. Superoxide B. Hydrogen peroxide C. Hydroxyl radical D. Nitric oxide Correct Answer: C

Question 60

What is the role of glutathione peroxidase?

Answer 60

A. Converts lipid radicals to water B. Removes hydrogen peroxide C. Generates hydroxyl radicals D. Breaks down fatty acids Correct Answer: B

Question 61

Which metal ion contributes to ROS generation in estrogen metabolism?

Answer 61

A. Zinc B. Copper C. Iron D. Sodium Correct Answer: B

Question 62

Which organelle contributes to ROS through xanthine oxidase activity?

Answer 62

A. Nucleus B. Golgi body C. Peroxisome D. Endoplasmic reticulum Correct Answer: C

Question 63

Which of the following enhances HIV gene expression through oxidative stress?

Answer 63

A. Lipid peroxides B. Nuclear factor kappa B (NF-κB) C. Glutathione dismutase D. Beta-carotene Correct Answer: B

Question 64

Assertion: Copper catalyzes DNA damage through ROS generation. Reason: Copper reacts with hydrogen peroxide to produce hydroxyl radicals.

Answer 64

A. Both A and R are true, and R explains A. Correct Answer: A

Question 65

Assertion: Glutathione peroxidase requires selenium as a cofactor. Reason: Selenium deficiency can impair antioxidant defense mechanisms.

Answer 65

A. Both A and R are true, and R explains A. Correct Answer: A

Question 66

Assertion: Vitamin E acts in aqueous environments. Reason: Vitamin E is lipid-soluble and protects membranes.

Answer 66

A. Both A and R are true, but R does not explain A. Correct Answer: B

Question 67

Assertion: ROS accelerate aging. Reason: They induce DNA mutations, protein damage, and lipid peroxidation.

Answer 67

A. Both A and R are true, and R explains A. Correct Answer: A

Question 68

Assertion: Xanthine oxidase protects tissues from ROS. Reason: It metabolizes hydrogen peroxide into water and oxygen.

Answer 68

C. A is true, R is false. Correct Answer: C

Question 69

Copper can promote ROS generation via Fenton-like reactions.

Answer 69

True

Question 70

Hydrogen peroxide directly breaks DNA strands without any cofactors.

Answer 70

False

Question 71

Glutathione is regenerated in the body using NADPH.

Answer 71

True

Question 72

ROS are produced only during pathological conditions.

Answer 72

False

Question 73

Selenium is a critical component of glutathione peroxidase.

Answer 73

True

Question 74

Vitamin C is lipid-soluble and acts in membranes.

Answer 74

False

Question 75

NF-κB activation is linked to oxidative stress in HIV infection.

Answer 75

True

Question 76

DNA strand breaks from oxidative damage are irreversible.

Answer 76

False

Question 77

Glutathione peroxidase converts lipid hydroperoxides into non-toxic alcohols.

Answer 77

True

Question 78

Manganese is a required mineral for catalase activity.

Answer 78

False