First Professional MBBS Examination
2021
(February)
BIOCHEMISTRY
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Paper-IFull Marks: 100
Time: 3 hours
The figures in the margin indicate
full marks for the questions
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Write the answers to the two Halves in separate booksAnswer all questions
FIRST HALF
1. What are the causes of glycosuria? What is renal threshold value for
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glucose? What is the normal fasting and postprandial plasma glucose level?Write briefly on regulation of plasma glucose level. (4 + 1 + 2 + 8 = 15)
2. What do you mean by oxidative phosphorylation? How does it differ from
substrate level phosphorylation? Discuss briefly on chemiosmotic hypothesis of
oxidative phosphorylation. Write a note on coupler and uncoupler of oxidative
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phosphorylation. (1 + 2 + 7 + 5 = 15)3. For the following MCQ-type questions, write down the answers (a), (b), (c) or
(d) against the questions in the answer booklet: ( 1 x10 = 10)
(i) Which one of the following is also called invertase?
(a) Sucrase
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(b) Lactase(c) Maltase
(d) Isomaltase
(ii) Which one of the following is a heteropolysaccharide?
(a) Insulin
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(b) Glycogen(c) Dextran
(d) Hyaluronic acid
(iii) Ceramide is a
(a) simple lipid
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(b) phospholipid(c) glycolipid
(d) derived lipid
(iv) GMI, the receptor for cholera toxin, is a
(a) phospholipid
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(b) transmembrane protein(c) glycolipid
(d) peripheral membrane protein
(v) Which of the following is an essential fatty acid belonging to W3 series?
(a) Arachidonic acid
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(b) Linoleic acid(c) linolenic acid
(d) linolenic acid
(vi) Which of the following amino acids contains an SH group?
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(a) Cystine(b) Lysine
(c) Cysteine
(d) Methionine
(vii) Which of the following is a high energy compound?
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(a) Glucose and phosphate(b) Fructose 1,6-bisphosphate
(c) Glyceraldehyde 3 phosphate
(d) 1,3-bisphosphoglycerate
(viii) Methotrexate inhibits which enzyme?
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(a) Xanthine oxidase(b) Dihydrofolate reductase
(c) Adenine phosphoribosyltransferase
(d) Hypoxanthine guanine phoribosyltransferase
(ix) Which of the following is an uncoupler of oxidative phosphorylation?
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(a) Cyanide(b) Oligomycin
(c) Thermogenin
(d) Carbon monoxide
(x) Main fuel for muscle contraction during short-term maximum exertion is
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(a) muscle glycogen
(b) muscle reserve of TAG
(c) plasma glucose
(d) plasma-free fatty acids
4. A 45-year-old moderately obese diabetic patient was brought to the medical
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emergency in an unconscious state. He was breathing deeply and rapidly. Thebreath did not smell of acetone or alcohol. Signs of mild dehydration such as
dry tongue. Weak and rapid pulse and low blood pressure were present.
For the last 2 days the patient had hectic sessions of physical activity when he
went to a hill station for recreation. He had rich meals during this period often
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accompanied by drinking till late night. While driving back home early in themorning the family members noticed that he was disoriented and his speech
was incoherent.
Blood and urine sample were obtained for analysis :
Investigation
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Patient's reportReference range
Random plasma glucose 85 mg/dl
140 mg/dl
pH
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7?327?35 - 7?43
Plasma Bicarbonate
20 mmol/l
21-28 mmol/l
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PCO232 mm.Hg
36-46 mm.Hg
Lactic acid
9?8 mmol/l
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0?44-1?4 mmol/lUrine Examination--Normal Sugar. Protein and ketone bodies absent.
(a) What is the biochemical abnormality of this patient? 2
(b) What is your idea regarding clinical condition of the patient that might have
led to the above biochemical abnormality? 2
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(c) What is the role of the following in causing the patient's problems? 3+3=6(i) Severe muscular exercise
(ii) Acute alcohol intoxication
SECOND HALF
5. Write short notes on (any seven) : 5?7=35
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(a) Reverse cholesterol transport(b) Lipotropic factors
(c) Primary and secondary bile acids
(d) Acyl carrier protein
(e) Biosynthesis and function of nitric oxide
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(f) Polyamines and their functions(g) Phenylketonuria
(h) Hartnup disease
6. Justify the statements : 2?5=10
(a) Bioavailability of calcium from milk is maximum.
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(b) Urea cycle is a bicycle.(c) PLP acts as a Schiff base in transamination reaction.
(d) Bleeding time is prolonged in obstructive jaundice.
(e) HDL cholesterol is regarded as a good cholesterol.
7. Discuss briefly the professional qualities a doctor should possess. 5
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* * *SM-21--1170/8 SS/MBBS-I/BIO-I/02-21