Daily Bugle's Biochem Test
Questions and Answers
- 1.
Characteristic sign of glycogenosis is muscle pain during physical work. Blood examination usually reveals hypoglycemia. This pathology is caused by congenital deficiency of the following enzyme:
- A.
Glycogen phosphorylase
- B.
γ-amylase
- C.
Glucose 6-phosphate dehydrogenase
- D.
α-amylase
Correct Answer
A. Glycogen phosphorylaseExplanation
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- 2.
Pancreas is known as a mixed gland. Endocrine functions include production of insulin by beta cells. This hormone affects metabolism of carbohydrates. What is its effect on the activity of glycogen phosphorylase (GP) and glycogen synthase (GS)?
- A.
It inhibits GP and activates GS
- B.
It inhibits both GP and GS
- C.
It activates both GP and GS
- D.
It activates GP and inhibits GS
Correct Answer
A. It inhibits GP and activates GSExplanation
Insulin, produced by the beta cells of the pancreas, has a dual effect on the activity of glycogen phosphorylase (GP) and glycogen synthase (GS). Insulin inhibits GP, which is responsible for breaking down glycogen into glucose, thereby reducing the release of glucose into the bloodstream. On the other hand, insulin activates GS, which promotes the synthesis of glycogen from glucose, leading to glycogen storage. Therefore, the correct answer is that insulin inhibits GP and activates GS.Rate this question:
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- 3.
A patient suffering from diabetes mellitus fainted after the introduction of insulin, and then cramps appeared. What level of sugar was determined in the patient's blood by means of biochemical analysis?
- A.
3.3 mM/1
- B.
5.5 mM/1
- C.
8.0 mM/1
- D.
1.5 mM/1
Correct Answer
D. 1.5 mM/1Explanation
When a patient with diabetes mellitus faints after the introduction of insulin and experiences cramps, it suggests that their blood sugar level has dropped significantly. Insulin helps to lower blood sugar levels, and if too much insulin is administered or the patient's blood sugar is already low, it can lead to hypoglycemia. A blood sugar level of 1.5 mM/1 is considered low and indicates hypoglycemia in this case.Rate this question:
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- 4.
A 39 old male patient was diagnosed with a Wernicke-Korsakoff syndrome, caused by a severe deficiency of thiamine pyrophosphate (TPP) mostly resulting by chronic, heavy alcohol consumption which interferes with the intestinal absorption of thiamin. Which enzyme of pentose phosphate pathway needs TPP as a coenzyme?
- A.
Phosphopentose isomerase
- B.
Transketolase Lactonase
- C.
Transketolase
- D.
Transaldolase
Correct Answer
C. TransketolaseExplanation
Transketolase is the enzyme of the pentose phosphate pathway that requires thiamine pyrophosphate (TPP) as a coenzyme. In Wernicke-Korsakoff syndrome, there is a severe deficiency of TPP due to chronic alcohol consumption, leading to impaired function of transketolase. This deficiency disrupts the normal metabolism of carbohydrates, ultimately resulting in the symptoms associated with the syndrome.Rate this question:
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- 5.
A patient complains about dyspnea provoked by the physical activity. Clinical examination revealed anaemia and presence of the paraprotein in the zone of gamma-globulins. To confirm the myeloma diagnosis it is necessary to determine the following index in the patient’s urine:
- A.
Bilirubin
- B.
Bence Jones protein
- C.
Ceruloplasmin
- D.
Antitrypsin
Correct Answer
B. Bence Jones proteinExplanation
To confirm the diagnosis of myeloma, it is necessary to determine the presence of Bence Jones protein in the patient's urine. Bence Jones protein is a type of abnormal protein produced by plasma cells in patients with multiple myeloma. Its presence in the urine is a characteristic feature of the disease. Dyspnea provoked by physical activity, along with the clinical findings of anemia and the presence of paraprotein in the gamma-globulin zone, further support the suspicion of myeloma. Therefore, the presence of Bence Jones protein in the urine would help confirm the diagnosis.Rate this question:
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- 6.
A tooth extraction in a patient with chronic persistent hepatitis was complicated with prolonged hemorrhage. What is the reason for the haemorrhagic syndrome?
- A.
Increase in thromboplastin production
- B.
Decrease in thrombin production
- C.
Fibrinolysis intensification
- D.
Decrease in fibrin production
Correct Answer
B. Decrease in thrombin productionExplanation
In a patient with chronic persistent hepatitis, the liver function is compromised. Thrombin is a protein produced in the liver that plays a crucial role in blood clotting. When thrombin production is decreased, it can lead to a decrease in the formation of fibrin, a protein involved in the clotting process. This can result in prolonged hemorrhage, as the blood is unable to clot effectively. Therefore, the decrease in thrombin production is the reason for the haemorrhagic syndrome in this patient.Rate this question:
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- 7.
A patient is diagnosed with hereditary coagulopathy that is characterised by factor VIII deficiency. Specify the phase of blood clotting during which coagulation will be disrupted in the given case:
- A.
Thrombin formation
- B.
Fibrin formation
- C.
Clot retraction
- D.
Thromboplastin formation
Correct Answer
D. Thromboplastin formationExplanation
In hereditary coagulopathy with factor VIII deficiency, the phase of blood clotting during which coagulation will be disrupted is thromboplastin formation. Thromboplastin is a complex of proteins that is released by damaged tissues and initiates the clotting cascade. Factor VIII plays a crucial role in the formation of thromboplastin. Without sufficient factor VIII, the formation of thromboplastin is impaired, leading to disrupted blood clotting.Rate this question:
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- 8.
In order to speed up healing of a wound of oral mucosa a patient was prescribed a drug that is a thermostable protein occuring in tears, saliva, mother’s milk as well as in a new-laid hen’s egg. It is known that this protein is a factor of natural resistance of an organism. What is it called?
- A.
Lysozyme
- B.
Interleukin
- C.
Interferon
- D.
Complement
Correct Answer
A. LysozymeExplanation
Lysozyme is a thermostable protein found in tears, saliva, mother's milk, and new-laid hen's eggs. It is known to be a factor of natural resistance in the body. This protein has antimicrobial properties and can help speed up the healing process of wounds in the oral mucosa. Therefore, lysozyme is the correct answer.Rate this question:
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- 9.
An infant born prematurely 2 days ago presents with yellow coloring of skin and mucosa. Such a condition in the infant is caused by temporary deficiency of the following enzyme:
- A.
Biliverdine reductase
- B.
Heme oxygenase
- C.
Aminolevulinate synthase
- D.
UDP-glucuronyl transferase
Correct Answer
D. UDP-glucuronyl transferaseExplanation
The yellow coloring of the skin and mucosa in the infant is a condition known as jaundice. Jaundice in newborns is commonly caused by a temporary deficiency of the enzyme UDP-glucuronyl transferase. This enzyme is responsible for the conjugation of bilirubin, a byproduct of red blood cell breakdown, making it soluble and easily excreted by the body. Without sufficient UDP-glucuronyl transferase, bilirubin accumulates in the body, leading to the yellow discoloration seen in jaundice. Biliverdine reductase, heme oxygenase, and aminolevulinate synthase are not directly involved in the metabolism of bilirubin and are not associated with jaundice in newborns.Rate this question:
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- 10.
A 48 y.o. patient was admitted to the hospital with complaints about weakness, irritability, sleep disturbance. Objectively: skin and scleras are yellow. In blood: conjugated bilirubin, cholalemia. Feces are acholic. Urine is of dark colour (bilirubin). What jaundice is it?
- A.
Gilbert’s syndrome
- B.
Parenchymatous
- C.
Mechanic
- D.
Crigler-Najjar syndrome
Correct Answer
C. MechanicExplanation
The correct answer is Mechanic. The patient's symptoms and objective findings suggest obstructive jaundice, which is caused by a blockage in the bile ducts. The yellowing of the skin and scleras, presence of conjugated bilirubin and cholalemia in the blood, acholic feces, and dark-colored urine (bilirubinuria) are all indicative of obstructive jaundice. Mechanic jaundice refers to jaundice caused by a mechanical obstruction in the bile ducts, such as a gallstone or tumor.Rate this question:
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- 11.
Feces of a patient contain high amount of undissociated fats and have grayish-white color. Specify the cause of this phenomenon:
- A.
Hypoactivation of pepsin by hydrochloric acid
- B.
Obturation of bile duct
- C.
Cholaemia
- D.
Bilirubinuria
Correct Answer
B. Obturation of bile ductExplanation
The high amount of undissociated fats and grayish-white color in the feces of a patient suggests that the cause of this phenomenon is the obturation of the bile duct. When the bile duct is obstructed, it prevents the flow of bile from the liver to the intestine, leading to the accumulation of undigested fats in the feces. This can result in the characteristic grayish-white color of the feces.Rate this question:
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- 12.
A 16-year-old adolescent is diagnosed with hereditary UDP (uridine di- phosphate) glucuronyltransferase deficiency. Laboratory tests revealed hyperbilirubinemia caused mostly by increased blood content of the following substance:
- A.
Conjugated bilirubin
- B.
Unconjugated bilirubin
- C.
Stercobilinogen
- D.
Biliverdin
Correct Answer
B. Unconjugated bilirubinExplanation
The correct answer is unconjugated bilirubin. UDP glucuronyltransferase is an enzyme responsible for conjugating bilirubin in the liver, which makes it water-soluble and allows for its excretion in bile. A deficiency in this enzyme leads to impaired conjugation of bilirubin, resulting in an accumulation of unconjugated bilirubin in the blood. This leads to hyperbilirubinemia, a condition characterized by elevated levels of bilirubin in the blood. Conjugated bilirubin is not increased in this condition because it is the conjugation process that is impaired. Stercobilinogen and biliverdin are not directly related to this condition.Rate this question:
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- 13.
A 1,7-year-old child with a developmental delay and manifestations of self-agression has the concentration of uric acid in blood at the rate of 1,96 millimole/l. What metabolic disoder is this typical for?
- A.
Gierke’s disease
- B.
Acquired immunodeficiency syndrome
- C.
Cushing’s basophilism
- D.
Lesch-Nyhan syndrome
Correct Answer
D. Lesch-Nyhan syndromeExplanation
Lesch-Nyhan syndrome is a metabolic disorder characterized by a deficiency of the enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRT), which leads to an accumulation of uric acid in the blood. This syndrome typically presents with developmental delay and self-aggression, as seen in the 1.7-year-old child described in the question. The concentration of uric acid in the blood, which is elevated in Lesch-Nyhan syndrome, further supports this diagnosis. Gierke's disease, acquired immunodeficiency syndrome, and Cushing's basophilism are not associated with the symptoms and uric acid concentration mentioned in the question.Rate this question:
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- 14.
Before the cells can utilize the glucose, it is first transported from the extracellular space through the plasmatic membrane inside them. This process is stimulated by the following hormone:
- A.
Insulin
- B.
Glucagon
- C.
Aldosterone
- D.
Adrenalin
Correct Answer
A. InsulinExplanation
Insulin is the correct answer because it is the hormone that stimulates the transportation of glucose from the extracellular space into the cells through the plasmatic membrane. Insulin is produced by the pancreas and plays a crucial role in regulating blood sugar levels by facilitating the uptake of glucose by cells, particularly in muscle and adipose tissue. Without insulin, glucose cannot enter the cells and be utilized for energy production.Rate this question:
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- 15.
Experimental studies revealed steroid hormones to have an effect on proteosynthesis. They influence synthesis of the following substances:
- A.
Specific transfer RNA
- B.
Adenosine triphosphate
- C.
Specific ribosomal RNA
- D.
Specific messenger RNA
Correct Answer
D. Specific messenger RNAExplanation
Steroid hormones have been found to affect proteosynthesis, specifically the synthesis of specific messenger RNA. Messenger RNA (mRNA) is responsible for carrying the genetic information from DNA to the ribosomes, where it is used as a template for protein synthesis. Steroid hormones can regulate gene expression by binding to specific receptors and influencing the transcription of mRNA molecules. This can lead to changes in the synthesis of specific proteins in the cell.Rate this question:
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- 16.
Examination of a child who hasn’t got fresh fruit and vegetables during winter revealed numerous subcutaneous hemorrhages, gingivitis, carious cavities in teeth. What vitamin combination should be prescribed in this case?
- A.
Thiamine and pyridoxine
- B.
Calciferol and ascorbic acid
- C.
Ascorbic acid and rutin
- D.
Folic acid and cobalamin
Correct Answer
C. Ascorbic acid and rutinExplanation
The child in this case is showing signs of scurvy, which is caused by a deficiency in vitamin C (ascorbic acid). Ascorbic acid is necessary for the synthesis of collagen, which is important for maintaining the integrity of blood vessels and connective tissues. Rutin is a flavonoid that helps strengthen blood vessels and can enhance the effects of vitamin C. Therefore, prescribing a combination of ascorbic acid and rutin would help address the child's symptoms and deficiencies.Rate this question:
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- 17.
What vitamin deficit causes the simultaneous disorder of reproductive function and dystrophy of skeletal musculature?
- A.
Vitamin D
- B.
Vitamin Е
- C.
Vitamin K
- D.
Vitamin K1
Correct Answer
B. Vitamin ЕExplanation
Vitamin E deficiency can cause both reproductive function disorders and skeletal muscle dystrophy. Vitamin E is an antioxidant that plays a crucial role in protecting cell membranes and preventing oxidative damage. Reproductive function relies on healthy cell membranes, and vitamin E deficiency can lead to impaired reproductive hormone synthesis and function. Additionally, skeletal muscle dystrophy can occur due to oxidative damage and impaired muscle cell integrity caused by vitamin E deficiency.Rate this question:
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- 18.
A 48-year-old female patient with a history of cholelithiasis has recurring steatorrhea. What vitamin deficiency may develop as a complication of the current disease?
- A.
B6
- B.
C
- C.
B12
- D.
K
Correct Answer
D. KExplanation
Cholelithiasis is the presence of gallstones in the gallbladder, which can lead to blockage of the bile ducts and impair the absorption of fat-soluble vitamins, including vitamin K. Steatorrhea, which is the presence of excessive fat in the stool, is a common symptom of malabsorption, indicating that the patient is not absorbing enough dietary fat. Since vitamin K is essential for blood clotting, a deficiency in this vitamin can lead to abnormal bleeding and bruising. Therefore, a vitamin K deficiency may develop as a complication of cholelithiasis.Rate this question:
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- 19.
Preventive examination of 1-1.5- year-old children living in an orphanage revealed focal thickening of ribs and wri-sts, bowed legs. The dentist pointed out delayed teething, wrong eruption order, irregular mineralization of the enamel and dentin, high-arched palate. What disease has developed in children?
- A.
Metabolic calcification
- B.
Osteomalacia
- C.
Dystrophic calcification
- D.
Rickets
- E.
Metastatic calcification
Correct Answer
D. RicketsExplanation
The symptoms described in the question, such as bowed legs, delayed teething, and irregular mineralization of the enamel and dentin, are characteristic of rickets. Rickets is a condition that occurs due to a deficiency in vitamin D, calcium, or phosphate, leading to impaired bone development and mineralization. The focal thickening of ribs and wrists, as well as the high-arched palate, further support the diagnosis of rickets. Metabolic calcification, osteomalacia, dystrophic calcification, and metastatic calcification are not associated with the specific symptoms mentioned.Rate this question:
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- 20.
The patient, who for a long time has been keeping to an unbalanced low-protein diet, developed fatty liver infiltration. Name the substabce, absence of which in the diet can lead to this condition:
- A.
Arachidonic acid
- B.
Methionine
- C.
Alanine
- D.
Cholesterol
Correct Answer
B. MethionineExplanation
Methionine is an essential amino acid that cannot be synthesized by the body and must be obtained through the diet. It plays a crucial role in the synthesis of proteins, as well as in various metabolic processes. A low intake of methionine can lead to a deficiency, which can result in the development of fatty liver infiltration. This is because methionine is necessary for the metabolism of fats in the liver, and its absence can lead to an accumulation of fat in the liver cells.Rate this question:
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- 21.
A 25-year-old patient with a heredi-tary enzymopathy (Gilbert’s disease) has a disorder of bilirubin conjugation in liver. What enzyme is not synthesized in this patient?
- A.
UDP-glucose pyrophosphorylase
- B.
UDP-glucuronyl transferase
- C.
UDP-glycogen transferase
- D.
Mido phosphoribosyl transferase
Correct Answer
B. UDP-glucuronyl transferaseExplanation
UDP-glucuronyl transferase is not synthesized in this patient. This enzyme is responsible for the conjugation of bilirubin in the liver, which is necessary for its excretion. In Gilbert's disease, there is a deficiency or reduced activity of UDP-glucuronyl transferase, leading to impaired bilirubin conjugation and increased levels of unconjugated bilirubin in the blood. This can result in jaundice and other symptoms associated with the disease.Rate this question:
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- 22.
For several days a 55-year-old woman has been suffering from pain attacks in the right upper quadrant after eating fatty foods. Visually, there is yellowness of sclera and skin. The pati ent has acholic stool, beer-colored urine. What substance present in the patient’s urine causes its dark color?
- A.
Unconjugated bilrubin
- B.
Stercobilin
- C.
Conjugated bilirubin
- D.
Ketone bodies
Correct Answer
C. Conjugated bilirubinExplanation
The correct answer is Conjugated bilirubin. In this scenario, the patient is experiencing symptoms of jaundice, including yellowing of the skin and sclera. The presence of acholic stool (pale or clay-colored) and beer-colored urine suggests a blockage in the bile ducts, preventing the excretion of bilirubin into the intestines. As a result, the conjugated bilirubin is being excreted in the urine, causing its dark color. Unconjugated bilirubin is not water-soluble and is not excreted in the urine. Stercobilin is responsible for the brown color of feces. Ketone bodies are not related to the symptoms described.Rate this question:
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- 23.
A 25-year-old patient has been diagnosed with chronic hepatitis. The patient complains of 10 kg weight loss within 2 months. Objectively: the patient has dry peeling skin, pale with yellow shade, petechial haemorrhages, stomatorrhagia. Petechial haemorrhagesand stomatorrhagia are caused by the disturbance of the following hepatic function:
- A.
Chromogenic
- B.
Protein synthesizing
- C.
Detoxication
- D.
Glycogen synthesizing
Correct Answer
B. Protein synthesizingExplanation
The correct answer is protein synthesizing. Chronic hepatitis can lead to liver damage, which impairs the liver's ability to synthesize proteins. This can result in a decrease in the production of clotting factors, leading to petechial hemorrhages and stomatorrhagia (bleeding from the mouth). Additionally, the liver plays a role in the metabolism of bilirubin, and when it is not functioning properly, it can result in jaundice, which explains the patient's pale skin with a yellow shade.Rate this question:
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- 24.
Proteins are of great importance for vital functions. What value of pH results in zero electrophoretic mobility of gelatin (gelatin isoelectric point equals 4,7)?
- A.
7,0
- B.
14,0
- C.
9,4
- D.
4,7
Correct Answer
D. 4,7Explanation
The isoelectric point (pI) of a protein is the pH at which it has no net charge. Gelatin, in this case, has an isoelectric point of 4.7. At this pH, the positive and negative charges on the gelatin molecule balance each other out, resulting in zero electrophoretic mobility. Therefore, the correct answer is 4.7.Rate this question:
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- 25.
Tricarboxylic acid cycle is a general way of carbohydrates, amino acids, and fatty acids oxidation. Specify the acid with which acetyl-CoA reacts first in tricarboxylic acid cycle:
- A.
Citric
- B.
Oxaloacetic
- C.
Isocitric
- D.
Fumaric
Correct Answer
B. OxaloaceticExplanation
In the tricarboxylic acid cycle, acetyl-CoA reacts first with oxaloacetic acid. This reaction forms citric acid, which is the first intermediate in the cycle. The reaction between acetyl-CoA and oxaloacetic acid is catalyzed by the enzyme citrate synthase. This step is important for initiating the cycle and starting the process of oxidizing carbohydrates, amino acids, and fatty acids.Rate this question:
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- 26.
A patient with type I diabetes mellitus developed hyperketonemic coma. What acid-base imbalance will be observed in the patient?
- A.
Nongaseous acidosis
- B.
Nongaseous alkalosis
- C.
Gaseous acidosis
- D.
Gaseous alkalosis
Correct Answer
A. Nongaseous acidosisExplanation
In a patient with type I diabetes mellitus, the development of hyperketonemic coma is associated with an accumulation of ketones in the blood. This leads to an increase in the concentration of nonvolatile acids in the body, causing nongaseous acidosis. Nongaseous acidosis refers to an imbalance in the acid-base status of the body characterized by a decrease in pH and bicarbonate levels. This condition can be life-threatening and requires immediate medical intervention.Rate this question:
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- 27.
Gout develops when purine nucleotide metabolism is disturbed. A doctor prescribed the patient allopurinol that is a competitive inhibitor of:
- A.
Lactate dehydrogenase
- B.
Succinate dehydrogenase
- C.
Xanthine oxidase
- D.
Hexokinase
Correct Answer
C. Xanthine oxidaseExplanation
Gout is a condition caused by the buildup of uric acid crystals in the joints, which leads to inflammation and pain. Purine nucleotides are broken down into uric acid, and any disturbance in this metabolism can lead to increased levels of uric acid and the development of gout. Allopurinol is a medication that is commonly prescribed to treat gout because it inhibits the activity of xanthine oxidase, an enzyme involved in the production of uric acid. By inhibiting xanthine oxidase, allopurinol helps to lower uric acid levels and prevent gout attacks.Rate this question:
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- 28.
Hyperlipemia can be observed in 2-3 hours after eating fatty food. 9 hours later lipid content normalizes again. How can this condition be characterized?
- A.
Alimentary hyperlipemia
- B.
Retention hyperlipemia
- C.
Transport hyperlipemia
- D.
Hyperplastic obesity
- E.
Hypertrophic obesity
Correct Answer
A. Alimentary hyperlipemiaExplanation
Alimentary hyperlipemia can be characterized as a condition where there is an increase in lipid levels in the blood after consuming fatty food. In this case, hyperlipemia is observed within 2-3 hours after eating, indicating that the body is unable to process and metabolize the excess lipids effectively. However, after 9 hours, the lipid content returns to normal, suggesting that the body is able to regulate and normalize the lipid levels over time.Rate this question:
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- 29.
A 5-year-old child presents with abdominal distension, abdominal cramps, and diarrhea occurring 1-4 hours after drinking milk. Described symptoms are caused by the lack of enzymes that break up:
- A.
Saccharose
- B.
Maltose
- C.
Fructose
- D.
Lactose
Correct Answer
D. LactoseExplanation
The symptoms described, including abdominal distension, cramps, and diarrhea occurring after consuming milk, are indicative of lactose intolerance. Lactose is a sugar found in milk and other dairy products. In individuals with lactose intolerance, the body does not produce enough of the enzyme lactase, which is responsible for breaking down lactose. As a result, undigested lactose reaches the large intestine, where it is fermented by bacteria, leading to the symptoms mentioned.Rate this question:
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- 30.
If pH of a solution is lower than its isoelectric point, it means in this solution:
- A.
Anion and cation forms of amino acids are balanced
- B.
Cation forms of amino acids are prevalent
- C.
Certain protein aggregates are formed
- D.
Irreversible protein precipitation occurs
- E.
Anion forms of amino acids are prevalent
Correct Answer
B. Cation forms of amino acids are prevalentExplanation
If the pH of a solution is lower than its isoelectric point, it means that the solution is more acidic. At a lower pH, the solution has an excess of H+ ions, which will cause the amino acids to lose their positive charge and become predominantly in their cation forms. This is because at lower pH values, the amino acids will lose a proton from their amino group, resulting in the formation of cations. Therefore, the correct answer is that cation forms of amino acids are prevalent in this solution.Rate this question:
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- 31.
A patient presents with hypoxia. What metabolic process activates when oxygen supply is insufficient?
- A.
Urea cycle
- B.
Oxidative decarboxylation of keto acids
- C.
Pentose-phosphate pathway
- D.
Anaerobic glycolysis
Correct Answer
D. Anaerobic glycolysisExplanation
When oxygen supply is insufficient, the body switches to anaerobic glycolysis as a metabolic process to produce energy. Anaerobic glycolysis involves the breakdown of glucose into pyruvate, which is then converted into lactate. This process does not require oxygen and allows for the production of ATP to continue in the absence of sufficient oxygen.Rate this question:
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- 32.
Avidin - an egg white protein inhibits reception of biotin (carboxylase coenzyme) by the body. What reaction will be blocked by avidin administration?
- A.
NH3 attachment to glutamate
- B.
NH3 detachment from glutamine
- C.
CO2 attachment to pyruvate
- D.
Beta-oxidation of fatty acids
Correct Answer
C. CO2 attachment to pyruvateExplanation
Avidin, an egg white protein, inhibits the reception of biotin by the body. Biotin is a coenzyme that is required for various enzymatic reactions in the body. One of these reactions is the attachment of CO2 to pyruvate, which is a crucial step in the process of cellular respiration. Therefore, if avidin is administered, it will block the attachment of CO2 to pyruvate, hindering the normal functioning of cellular respiration.Rate this question:
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- 33.
During routine preventive examination the local pediatrician noticed a boy of short stature. Mental development of the child corresponds with his age. What endocrine disorder is it?
- A.
Cretinism
- B.
Acromegalia
- C.
Pituitary nanism
- D.
Gigantism
Correct Answer
C. Pituitary nanismExplanation
Pituitary nanism is the correct answer because it refers to a condition where there is a deficiency in the production of growth hormone by the pituitary gland, resulting in stunted growth and short stature. The fact that the boy's mental development corresponds with his age suggests that there is no cognitive impairment, which is consistent with pituitary nanism. Cretinism is characterized by both physical and mental developmental delays, acromegaly is a condition of excessive growth, and gigantism is also characterized by excessive growth, all of which do not match the given symptoms.Rate this question:
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- 34.
Eicosanoids synthesis begins with freeing polyene acids from membrane phospholipids by means of a specific phospholipase. Name this enzyme:
- A.
Cyclooxygenase
- B.
Phospholipase A2
- C.
Arginase
- D.
Phospholipase C
Correct Answer
B. Phospholipase A2Explanation
Phospholipase A2 is the correct answer for this question. Eicosanoids synthesis starts by releasing polyene acids from membrane phospholipids, and this is done by the enzyme phospholipase A2. This enzyme specifically breaks down the phospholipids in the cell membrane, releasing the polyene acids that are then used in the synthesis of eicosanoids. Cyclooxygenase, arginase, and phospholipase C are not involved in the initial step of freeing polyene acids from membrane phospholipids.Rate this question:
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- 35.
Infant death occurs due to cyanide poisoning. What is the biochemical mechanism of cyanides’ unfavorable action on the molecular level?
- A.
Inhibition of cytochrome oxidase
- B.
Chemical bounding to the substrates of TCA
- C.
Blockage of succinate dehydrogenase
- D.
Inactivation of oxygen molecule
- E.
Inhibition of cytochrome b
Correct Answer
A. Inhibition of cytochrome oxidaseExplanation
Cyanide is known to inhibit cytochrome oxidase, which is an enzyme involved in the electron transport chain of cellular respiration. This enzyme is responsible for transferring electrons to oxygen molecules, allowing for the production of ATP. By inhibiting cytochrome oxidase, cyanide prevents the electron transport chain from functioning properly, leading to a decrease in ATP production. This can have severe consequences on cellular metabolism, particularly in tissues with high energy demands such as the brain and heart, ultimately leading to infant death.Rate this question:
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- 36.
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:
- A.
Glucagon
- B.
Adrenaline
- C.
Insulin
- D.
Thyroid hormones
Correct Answer
D. Thyroid hormonesExplanation
Thyroid hormones are responsible for increasing the production of certain hormones that stimulate biological oxidation and heat formation in the cells. This is achieved through the uncoupling of mitochondrial electron transfer and oxidative phosphorylation. Therefore, the high resistance of "winter-swimmers" or "walruses" to low temperatures can be attributed to the increased production of thyroid hormones.Rate this question:
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- 37.
A 3-year-old girl with mental retardation has been diagnosed with sphingomyelin lipidosis (Niemann-Pick disease). In this condition synthesis of the following substance is disrupted:
- A.
Sphingosine
- B.
Glycosyltransferase
- C.
Sphingomyelinase
- D.
Gangliosides
- E.
Ceramides
Correct Answer
C. SphingomyelinaseExplanation
In Niemann-Pick disease, the synthesis of sphingomyelinase is disrupted. Sphingomyelinase is an enzyme responsible for breaking down sphingomyelin, a type of sphingolipid. Without functional sphingomyelinase, sphingomyelin cannot be properly broken down and metabolized, leading to its accumulation in various tissues and organs. This accumulation can cause the characteristic symptoms of Niemann-Pick disease, including mental retardation, hepatosplenomegaly, and neurologic deterioration. Therefore, the disruption of sphingomyelinase synthesis is the cause of the disease.Rate this question:
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- 38.
Examination of a man who hadn’t been consuming fats but had been getting enough carbohydrates and proteins for a long time revealed dermatitis, poor wound healing, vision impairment. What is the probable cause of metabolic disorder?
- A.
Lack of linoleic acid, vitamins A, D, E, K
- B.
Lack of vitamins PP, H
- C.
Low caloric value of diet
- D.
Lack of palmitic acid
- E.
Lack of oleic acid
Correct Answer
A. Lack of linoleic acid, vitamins A, D, E, KExplanation
The probable cause of the metabolic disorder is the lack of linoleic acid, vitamins A, D, E, and K. These nutrients are essential for maintaining healthy skin, proper wound healing, and good vision. Without an adequate intake of these nutrients, the body may experience dermatitis, poor wound healing, and vision impairment.Rate this question:
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- 39.
Examination of cell culture not from a patient with lysosomal pathology revealed accumulation of great quantity of lipids in the lysosomes. What of the following diseases is this disturbance typical for?
- A.
Gout
- B.
Phenylketonuria
- C.
Wilson disease
- D.
Tay-Sachs disease
Correct Answer
D. Tay-Sachs diseaseExplanation
Tay-Sachs disease is a lysosomal storage disorder characterized by the accumulation of lipids, specifically gangliosides, in the lysosomes. This accumulation occurs due to a deficiency of the enzyme hexosaminidase A, which is responsible for breaking down these lipids. As a result, the lipids build up and cause damage to the nerve cells, leading to the symptoms associated with Tay-Sachs disease. Therefore, the observation of a great quantity of lipids in the lysosomes of a cell culture suggests a disturbance typical for Tay-Sachs disease.Rate this question:
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- 40.
The key reaction of fatty acid synthesis is production of malonyl-CoA. What metabolite is the source of malonyl-CoA synthesis?
- A.
Succinyl-CoA
- B.
Acyl-CoA
- C.
Acetyl-CoA
- D.
Malonate
- E.
Citrate
Correct Answer
C. Acetyl-CoAExplanation
Acetyl-CoA is the source of malonyl-CoA synthesis. In the first step of fatty acid synthesis, acetyl-CoA is carboxylated to form malonyl-CoA. This reaction is catalyzed by the enzyme acetyl-CoA carboxylase, and it is the key step in the production of malonyl-CoA, which is an essential precursor for fatty acid synthesis. Therefore, acetyl-CoA is the correct answer as it is directly involved in the synthesis of malonyl-CoA.Rate this question:
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