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

ATAL BIHARI VAJPAYEE MEDICAL UNIVERSITY, LUCKNOW
MBBS 1st PROFESSIONAL EXAMINATION - JAN-2023
SUBJECT: BIOCHEMISTRY - PAPER - I
Max. Marks: 100
TIME: 3 Hrs

Note: Attempt all questions. Answer Part - I and Part - II in separate answer books. All parts of a question should be answered together.

PART - I
PAPER CODE: 2311130003

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

A 45-year-old man presents to medicine OPD with morbid obesity for routine check-up. He provides a family history of ischemic heart disease. The consulting doctor ordered various blood tests including lipid profile.

• Describe different types of lipoproteins.

• Why is HDL called good cholesterol?

• Discuss the role of LDL in atherosclerosis.

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

• Describe allosteric regulation of enzymes.

• Describe the process of gluconeogenesis and its regulation.

• Describe metabolic adaptations during starvation.

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

• Briefly describe the chemiosmotic theory of ATP generation.

• Explain the importance of glycemic index.

• Briefly describe Cytochrome P450.

• Why creatinine is a better marker of renal function than urea.

• Antioxidants.

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

1. Co-factor required for optimal action of Xanthine oxidase is:
   a) Zinc
   b) Cobalt
   c) Molybdenum
   d) Manganese

2. To which class of enzymes does alcohol dehydrogenase belong:
   a) Hydrolase
   b) Isomerase
   c) Ligase
   d) Oxidoreductase

3. The average daily nutrient level estimated to fulfill the requirement of 97-98% individuals of a particular age, and life stage is known as:
   a) Estimated Average Requirement
   b) Recommended Dietary Allowance
   c) Adequate Intake
   d) Tolerable Upper Intake Level

4. Glucose uptake by:
   a) Brain cells is through energy-requiring (active) transport.
   b) Intestinal mucosal cells requires insulin.
   c) Liver cells is through facilitated diffusion involving a glucose transporter.
   d) Most cells is through simple diffusion up a concentration gradient.

5. Which of the following statements about vitamin C is correct? Vitamin C is:
   a) A competitor of iron absorption in the intestine.
   b) A fat-soluble vitamin stored in adipose tissue.
   c) A coenzyme in several enzymic reactions such as the hydroxylation of proline.
   d) A coenzyme in several enzymic reactions such as the carboxylation of glutamate.

6. Which one of the following clinical findings is most likely to be seen in a patient with poorly controlled type 1 diabetes mellitus?
   a) Blood pH of 7.4
   b) Positive test for protein in the urine
   c) Hemoglobin A1c value of 5.8%
   d) Negative test result for a reducing sugar in the urine

7. Which of the following is a rich source of trans fatty acids?
   a) Peanut oil
   b) Red meat
   c) Baked goods
   d) Fish

8. Allosteric inhibition:
   a) Makes active site unfit for substrate
   b) Controls excess formation of end product
   c) Both (A) and (B)
   d) None of these

9. Which one of the following conditions decreases the oxidation of acetyl coenzyme A by the citric acid cycle?
   a) A high availability of calcium
   b) A high acetyl CoA/CoA ratio
   c) A low ATP/ADP ratio
   d) A low NAD+/NADH ratio

10. Which one of the enzymes listed below requires tetrahydrobiopterin as a coenzyme?
    a) Alanine transaminase
    b) Glutamate dehydrogenase
    c) Phenylalanine hydroxylase
    d) Histidine decarboxylase

PART - II PAPER CODE: 2311230003

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

A 3-year-old female child belonging to a very poor socio-economic status was brought to the OPD by her mother who complained her child suffered from frequent fractures and bone deformities. On examination, the child had bowing of the lower extremities. Biochemical Investigations revealed very low serum levels of Vitamin D, phosphorus, and subnormal levels of calcium.
a) What is your provisional diagnosis?
b) Explain the metabolism of Vitamin D using a flowchart.
c) Describe the daily requirement and dietary sources rich in Vitamin D.

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

a) Explain the action of hormones via calcium and phosphatidylinositides.
b) Which enzyme assays will you use in a patient suspected of myocardial infarction? Explain with their timeline.
c) Why do diabetic patients develop cataracts at a younger age?

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

a) What is the significance of NADPH in metabolism?
b) Why is sodium fluoride used while collecting blood samples for glucose estimation?
c) Describe briefly phase 1 reactions of xenobiotic metabolism.
d) Enumerate micro and macrovascular complications of Diabetes Mellitus.
e) Explain the significance of estimating Body Mass Index.

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

1. Malate shuttle is necessary for:
   a) Gluconeogenesis
   b) ATP generation
   c) Providing NADPH
   d) Glycogenolysis

2. The lipoprotein with fastest electrophoretic mobility and lowest triglyceride content is:
   a) VLDL
   b) IDL
   c) LDL
   d) HDL

3. Chylomicrons are formed within:
   a) Intestinal lumen
   b) Enterocytes
   c) Adipocytes
   d) Lymphatic vessels

4. Under starvation, enzyme which is inhibited is:
   a) Glucose 6 phosphatase
   b) Alanine transaminase
   c) Glucokinase
   d) Pyruvate carboxylase

5. In which of the following tissues/cells glucose uptake is insulin-dependent?
   a) Adipose
   b) Brain
   c) Liver
   d) RBC's

6. Alpha-linolenic acid is:
   a) Omega-3 fatty acid
   b) Omega-6 fatty acid
   c) Saturated fatty acid
   d) Trans fatty acid

7. A man complains of diarrhea with dairy products. He must avoid all except:
   a) Condensed milk
   b) Skimmed milk
   c) Yogurt
   d) Ice cream

8. Hyaluronic acid is seen in:
   a) Synovial fluid
   b) Cornea
   c) Cartilage
   d) Blood

9. Von Gierke's disease is characterized by the deficiency of:
   a) Glucose 6 phosphatase
   b) Glucose 6 phosphatase dehydrogenase
   c) Phosphorylase
   d) HMG-CoA reductase

10. Impaired glucose tolerance can occur with deficiency of:
    a) Copper
    b) Zinc
    c) Chromium
    d) Fluorine

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