Biochemistry Paper-1 (Supplementary), 2021 MBBS Batch ABVMU Lucknow

ATAL BIHARI VAJPAYEE MEDICAL UNIVERSITY, UTTAR PRADESH

MBBS 1st PROFESSIONAL SUPPLEMENTARY EXAMINATION

BIOCHEMISTRY - PAPER - I

TIME: 3 Hrs
Max. Marks: 100

Note: Attempt all questions. Answer Section - A and Section - B in separate answer books. All parts of a question should be answered together.

SECTION – A

PAPER CODE: 2321130003

Q.1 Long Answer Question (3 + 5 + 4 + 3 = 15 Marks)

Q.2 Short Notes Questions (Write within 500 words) (3 × 5 = 15 Marks)

Q.3 Short Answer Questions (Write within 100 words) (5 × 2 = 10 Marks)

Q.4 Multiple Choice Questions (1 × 10 = 10 Marks)

A 30-year-old bachelor who frequently suffered from upper respiratory infections and the common cold presented to the hospital with these symptoms as his main concern. He also reported having gum bleeding and joint pain. He responded that he doesn’t eat fruits or vegetables and only consumes food that has been stored. He was found to have pallor and swollen gums. On the lower extremities, petechiae were visible as cutaneous patches.

a) What is the probable diagnosis? What clinical findings led you to this diagnosis?
b) Explain the biochemical basis of the disorder.
c) Why pallor, petechiae & bleeding gums seen in this disorder, relate the biochemical reasons behind these findings.
d) How can this disorder be treated?

a) What is competitive inhibition of enzyme activity, write in brief with the help of a suitable example?
b) What are Glycogen storage diseases (GSD)? Write in brief about GSD-Type I.
c) What are the inhibitors of the electron transport chain (ETC) and how do they inhibit ETC?

a) Why sucrose behaves as a non-reducing sugar, Justify?
b) Explain why we cannot synthesize essential fatty acids though our cells have mechanisms for de novo synthesis of fatty acids.
c) Give reasons why the liver cannot utilize ketone bodies to fulfill its energy needs?
d) Explain how low-dose aspirin acts as a cardioprotective agent.
e) What is basal metabolic rate (BMR) and what are the factors which affect BMR?

• 1. Which of the following transport mechanisms does not operate by the primary active transport mechanism?
  a) Na⁺ / K⁺ pump
  b) Na⁺ / H⁺ pump
  c) Calcium pump
  d) Potassium-hydrogen pump

• 2. Which of the following disaccharide is used as a safe laxative in liver diseases?
  a) Isomaltose
  b) Cellobiose
  c) Allolactose
  d) Lactulose

• 3. The following is taken as a reference molecule to represent D and L isomerism:
  a) Glucose
  b) Fructose
  c) Ribose
  d) Glyceraldehyde

• 4. The hormone that can uncouple oxidative phosphorylation is:
  a) Insulin
  b) Glucagon
  c) Glucocorticoid
  d) Thyroxine

• 5. All cells produce free radicals, except:
  a) Macrophages
  b) Neutrophils
  c) Erythrocytes
  d) Basophils

• 6. Tetany is a feature of:
  a) Hypercalcemia
  b) Hypocalcemia
  c) Hypokalemia
  d) Hyperkalemia

• 7. Thiamin deficiency can be assessed by:
  a) Hepatocyte transketolase activity
  b) Erythrocyte transketolase activity
  c) Leukocyte transketolase activity
  d) Muscle transketolase activity

• 8. Sulfur containing vitamin:
  a) Riboflavin
  b) Folic acid
  c) Biotin
  d) Niacin

• 9. Menkes disease is associated with which enzyme deficiency?
  a) Lysyl oxidase
  b) Methionine synthase
  c) Glutamyl aminopeptidase
  d) Lysyl hydroxylase

• 10. In a well-fed state, the activity of CPT-1 in the outer mitochondrial membrane is inhibited by:
  a) Glucose
  b) Pyruvate
  c) Acetyl CoA
  d) Malonyl CoA

SECTION - B PAPER CODE: 2321230003

Q.1 Long Answer Question (4 + 5 + 3 + 3 = 15 Marks)

The main concerns of a 40-year-old woman from a mountainous area who visited the clinic were swelling in her neck, exhaustion, a deepening of her voice, dry skin, constipation, and a sensitivity to the cold. She also claimed to have put on weight recently. Her blood pressure was 110/60 mm Hg, her pulse was 58/min, and her body temperature was 96.4° F when she was examined. She had thick, pale, chilly skin, a bloated face, and a substantial amount of body fat. Her deep tendon reflexes were also delayed. She had a slightly enlarged, firm, mobile, non-nodular, firm, and uncomplicated thyroid gland. Her thyroid profile was as follows after investigations:

• Serum T3: 0.5 ng/ml (Normal: 0.6-1.8 ng/ml)

• Serum T4: 3.0 µg/dl (Normal: 3.2-12.6 µg/dl)

• Serum TSH: 21 µIU/dl (Normal: 0.35-5.5 µIU/dl)

a) What is the most probable diagnosis? Justify by giving points in favor of the given diagnosis.
b) Explain the biochemical basis of the given disorder.
c) What other investigations including supporting tests are needed to reach the diagnosis of the given disorder?
d) How can the condition be managed?

Q.2 Short Notes Questions (within 500 words) (3 × 5 = 15 Marks)

a) What is an anion gap and mention the conditions in which it gets increased?
b) Explain how Glucose-6-phosphate dehydrogenase (G-6-PD) deficiency leads to hemolytic anemia.
c) Explain the mechanism of action of Vitamin E as an antioxidant.

Q.3 Short Answer Questions (within 100 words) (5 × 2 = 10 Marks)

a) Justify the role of dietary fibers important in your diet.
b) Write in brief why HDL cholesterol is called good cholesterol.
c) How hypocalcemia leads to tetany?
d) Justify the detoxification function of glutathione.
e) Write in brief physiological uncouplers of oxidative phosphorylation.

Q.4 Multiple Choice Questions (1 × 10 = 10 Marks)

• 1. A child with low blood glucose is unable to do glycogenolysis or gluconeogenesis. Which of the following enzyme is missing in the child?
  a) Fructokinase
  b) Glucokinase
  c) Glucose-6-Phosphatase
  d) Transketolase

• 2. All of the following are associated with hypercholesterolemia EXCEPT:
  a) Myxedema
  b) Nephrotic syndrome
  c) Obstructive jaundice
  d) Diabetes insipidus

• 3. Beta oxidation in peroxisome generates:
  a) NADPH
  b) H₂O₂
  c) Long-chain fatty acid
  d) FADH₂

• 4. Endogenous Triglycerides are maximum in:
  a) Chylomicrons
  b) LDL
  c) VLDL
  d) HDL

• 5. Vitamin K-dependent clotting factor is:
  a) Factor I
  b) Factor VII
  c) Factor XI
  d) Factor XII

• 6. OGTT in non-pregnant adults is performed using:
  a) 75 gm of anhydrous glucose
  b) 100 gm of anhydrous glucose
  c) 75 gm of hydrous glucose
  d) 100 gm of hydrous glucose

• 7. Major storage and transport form of vitamin D3 is:
  a) Cholecalciferol
  b) 24,25 dihydroxy cholecalciferol
  c) 1,25 dihydroxy cholecalciferol
  d) 25 hydroxy cholecalciferol

• 8. Which of the isoenzyme variant of CK is elevated in myocardial infarction?
  a) CK-BB
  b) CK-MB
  c) CK-MM
  d) All of the above

• 9. Which of the following statements regarding Wilson’s disease is correct:
  a) Copper fails to be excreted in the bile
  b) Copper level in plasma is decreased
  c) Ceruloplasmin level is increased
  d) Intestinal absorption of copper is decreased

• 10. Hormone that binds to cell surface receptors and requires the second messenger cAMP is:
  a) Antidiuretic hormone
  b) Gastrin
  c) Oxytocin
  d) Thyrotropin-releasing hormone

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