Biological oxidation and Electron transport chain (Multiple choice questions) – solved- part-3

Q.1- Choose a site along the electron transport chain out of the following that is not coupled to ATP synthesis:

a) NADH- coenzyme Q (CoQ) reductase

b) Succinate-Co Q reductase

c) Cytochrome bc₁ reductase

d) Cytochrome oxidase

e) None of the above.

Q.2- Choose a statement out of the following that best describes the uncouplers of oxidative phosphorylation:

a) Uncouple ATP synthesis with phosphoenolpyruvate

b) Uncouple ATP/ADP translocation

c) Uncouple electron transport from oxygen reduction

d) Uncouple electron transport with ATP synthesis

e) Uncouple ATP synthesis with phosphoglycerate

Q.3- Which of the following statements best describes the mechanism of action of Oligomycin?

a)It inhibits NADH dehydrogenase

b) It is an uncoupler of oxidative phosphorylation

c) It inhibits ATP/ADP transporter

d) It is an inhibitor of cytochrome oxidase

e) It blocks the flow of protons through ATP synthase complex

Q.4- ADP transport into the mitochondrial matrix:

a) is an active transport process

b) is directly inhibited by valinomycin

c) is carried out through a shuttle present in outer mitochondrial membrane

d) is accompanied by ATP export from the mitochondrial matrix

e) is inhibited by Rotenone

Q.5- Which of the following enzymes catalyzes the conversion of Hydrogen peroxide to water?

a) Superoxide dismutase

b) Cytochrome P 450

c) Catalase

d) Hydratase

e) Dioxygenase

Q.6- Which of the following ETC components accepts only one electron?

a) Oxygen

b) FMN

c) FAD

d) Cytochrome b

e) Coenzyme Q

Q.7- Which of the following is a component of Succinate dehydrogenase in Electron transport chain?

a) Niacin

b) FMN

c) FAD

d) Coenzyme Q

e) Lipoic acid

Q.8- MELAS is a mitochondrial disorder characterized by mitochondrial encephalopathy, lactic acidosis and stroke-like episode. It is an inherited condition due to NADH: Q oxidoreductase (Complex I) or cytochrome oxidase (Complex IV) deficiency, caused by a mutation in mitochondrial DNA and may be involved in Alzheimer’s disease and diabetes mellitus. Due to the lack of functional mitochondria, what would be the net ATP that would be produced from one molecule of Glucose?

a) 1

b) 2

c) 4

d) 8

e) 0

Q.9- An 18- year -old cricket player sustains a compound fracture on the field. He is taken for surgery, during which anesthesiologist notes a significantly increased body temperature (104^OF). There is suspicion of malignant hyperthermia. Which of the following components of ETC is likely to be responsible for this phenomenon?

a) Complex I

b) Complex II

c) Complex III

d) Complex IV

e) ATP synthase complex

Q.10- A 43- year-old woman diagnosed with early-stage breast cancer elects to have a lumpectomy followed by radiation therapy because this regimen has been shown to be equivalent to mastectomy in such patients. Radiations work in part by:

a) Inhibiting NADH – cytochrome C reductase

b) Inhibiting cytochrome b-c1 complex

c) Generating reactive oxygen species

d) Oxidizing glutathione

e) Inhibiting ATP synthase complex

Q.11- An -8-year-old boy is seen by an ophthalmologist for difficulties in seeing in all visual fields as well as slow eye movements. The ophthalmologist finds pigmentary retinopathy and ophthalmoplegia. The child is suspected to have Kearns- Sayre syndrome, a disorder due to a mutation in complex II of ETC. The electron transport from which substance would be impaired?

a) Malate

b) Isocitrate

c) Succinate

d) Pyruvate

e) Alpha-ketoglutarate

Q.12- A 63- year-old man with a strong family history of Parkinson’s disease begins to show the signs of the disease “pin rolling tremors”. He visits his neurologist, who guides him about the recent research about coenzyme Q, which may stall the development of the disease. This component of ETC normally –

a) receives electrons directly from NADH

b) receives electrons directly from complex IV

c) receives electrons directly from FMN

d) transports ATP to the cytoplasm

e) Contains heme

Key to answers-

1)- b, 2)- d, 3)- e, 4)- d, 5)- c, 6)- d, 7)- c, 8)- b, 9)-e, 10)-c , 11)-c , 12)- c