Examples of Krok 1 tests

107. Mitochondria are subcellular organelles and are present in a cytoplasm of every cell exept mature red blood cells, bacteria, blue-green algae. What method is used principally for their isolation?

A. Differential centrifugation

B. Chromatography

C. Electrophoresis

D. Spectrophotometry

E. Gel-filtration

108. Enzymes of tricarboxylic acids cycle oxidize acetyl-CoA and produce 3 molecules of reduced NAD and one molecule of reduced FAD. Where are localized these enzymes?

A. In mitochondrial matrix

B. On plasma membrane

C. On external mitochondrial membrane

D. In cell cytoplasm

E. On inner mitochondrial membrane

109. A patient was admitted into hospital with a diagnosis diabetes mellitus type I. In metabolic changes the decrease of oxaloacetate synthesis rate is detected. What metabolic passway is damaged as a result?

1. Tricarboxylic acid cycle

2. Glycolysis

3. Cholesterol biosynthesis

4. Glycogen mobilization

5. Urea synthesis

110. Substrate phosphorylation is a process of phosphate residue transfer from macroergic donor substance to ADP or some other nucleoside diphosphate. What enzyme of tricarboxylic acid cycle participates in reaction of substrate phosphorylation?

1. Succinyl thiokinase

2. Citrate synthase

3. Succinate dehydrogenase

4. Fumarase

5. Alpha-ketoglutarate dehydrogenase complex

111. In a patient are manifested symptoms of intoxication with arsenic compounds. What metabolic process is damaged taking into account that arsen containing substances inactivate lipoic acid?

A. Oxidative decarboxylation of α-ketoglutarate

B. Fatty acids biosynthesis

C. Neutralization of superoxide anions

D. Coupling of oxidation and phopsphorylation

E. Microsomal oxidation

112. During metabolic process active forms of the oxygen including superoxide anion radical are formed in the human body. With help of what enzyme is this anion activated?

1. Superoxide dismutase

2. Catalase

3. Peroxidase

4. Glutathioneperoxidase

5. Glutathionereductase

113. ATP synthesis is totaly blocked in a cell. How will the value of membrane rest potential change?

A. It will disappear

B.It will be slightly increased

C. It will be considerably increased

D.First it will increase, then decrease

E. First it will decrease, then increase

114. Profuse foam appeared when dentist put hydrogen peroxide on the mucous of the oral cavity. What enzyme caused such activity?

A. Catalase

B. Cholinesterase

C. Acetyltransferase

D.Glucose-6-phosphate-dehydrogenase

E. Methemoglobinreductase

115. The next process occurs in suspension of mitochondria with ruptured inner membrane and provided with malate and oxygen:

1. Transport of electrons along enzymes of respiratory chain

2. Phosphorylation of ADP

3. Decrease of pH in the external medium

4. Increase of pH in mitochondrial matrix

5. Oxydative phosphorylation will take place

116. during the necropsy of a 20-year-old girl a pathologist concluded that the death of the patient had resulted from poisoning by cyanides. The activity of what enzyme is mostly inhibited by cyanides?

1. Cytochrome oxydase

2. Malate dehydrogenase

3. Heme synthase

4. Aspartate aminotransferase

5. Lactate dehydrogenase

117. CO is extremely dangerous poison as it irreversibly blocks repiratory chain of enzymes. At which point is arrested electron transport in presence of CO?

A. Cytochrome oxidase

2. Succinate dehydrogenase

3. Ubiquinon-cytochrome c reductase

4. Respiratory complex III

5. NADH₂-ubiquinon reductase

118. Some hormones are acting as uncouplers of oxidative phosphorylation. Chose from listed below hormones one which is considered as the best uncoupler;

1. Thyroxine

2. Norepinephrine

3. Testosterone

4. Insulin

5. Cortisol

119. Activation of membrane lipid peroxydation is one of the basic mechanisms of membrane structure and functions damage as well as the death of a cell. The cause of this pathology is:

1. Vitamin E deficiency

2. B₁₂-hypervitaminosis

3. B₁-deficiency

4. B₁-hypervitaminosis

5. B₁₂-deficiency

120. The production of thyroid hormones is stimulated under thyrotoxicosis. It leads to body weigh loss, tachycardia, and rise of psychic irritability. Choose the biochemical mechanism by which thyroid hormones affect the tissue bioenergetics from the listed below:

1. Uncoupling of oxidation and oxidative phosphorylation

2. Blockage of mitochondrial respiratory chain

3. Activation of substrate level phosphorylation

4. Blockage of substrate level phosphorylation

5. Activation of oxidation and oxidative phosphorylation

121. Hydrogen peroxide is harmful and extremely toxic to living cells. Chose an enzyme which is used by cells for neutralization of hydrogen peroxide:

1. Glutathion peroxidase

2. Cytochrome oxidase

3. NADP-H₂-oxidase

4. Cyclooxygenase

5. Monoamine oxidase

122. Superoxide anion is generated in course of tissue respiration and is a strong oxidant, possessing a harmful effect. What enzyme is involved in neutralization of this compound?

1. Superoxide dismutase

2. Monoamine oxidase

3. Peroxidase

4. Catalase

e. Xanthine oxidase

123. In diseases which are accompanied by hypoxia an incomplete reduction of oxygen molecule in respiratory chain and accumulation of hydrogen peroxide occurs. Note an enzyme which provides neutralization of hydrogen peroxide:

1. Glutathion peroxidase

2. Cytochrome oxidase

3. Succinate dehydrogenase

4. Glutathion reductase

5. Oxidase of reduced NADP

124. Cyanides are extremely dangerous poisons as they irreversibly block repiratory chain of enzymes. At which point is arrested electron transport in presence of cyanides?

A. Cytochrome oxidase

2. Succinate dehydrogenase

3. Ubiquinon-cytochrome c reductase

4. Respiratory complex III enzymes

5. NADH₂-ubiquinon reductase

125. High resistance of “winter-swimmers” (so-called “walruses”) to low temperatures is explained by increased production of certain hormones that stimulate the processes of biological oxidation and heat formation in the cells through the uncoupling of mitochondrial electron transfer and the oxidative phosphorylation. Choose the name of these hormones:

1. Thyroid hormones

2. Glucagone

3. Adrenaline

4. Insulin

5. Corticosteroids

126. during the necropsy of a 17-year-old girl a pathologist concluded that the death of the patient had resulted from poisoning by cyanides. The disturbance of what process became the most credible cause of the girl’s death?

1. Tissue respiration

2. Synthesis of vhemoglobin

3. Transport of oxygen by hemoglobin

4. Urea synthesis

5. Atherosclerosis

127. Infant death occurs due to cyanide poisoning. What is the biochemical mechanism of cyanides’ unfavorable action on the molecular level?

1. Inhibition of cytochrome oxidase

2. Chemical bounding to the substrates of TCA

3. Blockage of succinate dehydrogenase

4. Inactivation of oxygen molecule

5. Inhibition of cytochrome b

128. Cyanides are cellular poisons, inhibiting electron transport on terminal segment of respiratory chain in mitochondrias. What is the mechanism of their toxic effect?

1. Formation of a complex with Fe⁺³ form of cytochrome oxidase

2. Block up of electron transport on a level of NAD H –coenzyme Q-reductase.

3. Block up of electron transport from cytochrome bc₁.

4. Inhibition of ATP-synthase function

5. Uncoupling of respiration and oxidative phosphorylation in mitochondria

129. Enzymes of respiratory chain perform oxidation of substrates and transfer of reductive equivalents to oxygen with production of water molecules. Where they are located?

1. On inner mitochondrial membrane.

2. On cytoplasmic membrane

3. In cytoplasm

4. On outer mitochondrial membrane

5. In nucleus

130. Patient P. is working in chemical industry, connected with cyanic acid production. He complains in attacks of suffocation and dizziness. What is the mechanism of cyanides effect upon tissue respiration?

1. Interaction with heme of cytochrome a₃

2. Attacment to nitrogen atom in pyrimidine cycle of NAD

3. Block the activity of cytochrome c

4. Block bonding with an oxygen

5. Block the transfer of electrons from cytochrome bc₁

131. Coupling of tissue respiration and oxydative phosphorylation takes place in the presence of electrochemical gradient of H⁺ ions between mitochondrial matrix and intermembranous space. What substance from listed below can uncouple respiration and phosphorylation?

1. Rothenon

2. Somatotropin

3. Cyanides

4. Dinitrophenol

5. Glucose

132. Cytochromes are components of respiratory chain in mitochondrias, which transfer electrons from ubiquinon to molecular oxygen. What part of cytochrome molecule take part in oxydative-reductive reactions?

1. Iron atom

2. Vynil residue

3. Pyrrole cycle

4. Proteinous part

5. Methen bridge