Download MBBS UHS Lahore 1st Year Biochemistry II SEQ Question Paper

Download MBBS (Bachelor of Medicine and Bachelor of Surgery) UHS Lahore (University of Health Sciences Lahore) 1st Year Biochemistry II SEQ Previous Year Question Paper




(Short Essay Questions)

Max. Marks 32.5 Time Allowed 2 hours

1. a) Draw and label a diagram to illustrate the components,

organization and site specific inhibitors of electron transport chain.


b) How is 5?phosphoribosyl-1-pyrophosphate (PRPP) synthesized?

Name the amino acid which takes part in purine ring formation.


2. a) What are the biochemical events involved in the causation of

cataract in uncontrolled diabetes mellitus?


b) How creatine phosphate is synthesized? Calculate energy yield in

the form of mole of ATP from one mole of palmitate.


3. a) What are the enzyme deficiencies in essential fructosuria and

hereditary fructose intolerance? Write down the reactions catalyzed

by these enzymes. Which one of these two conditions leads to

severe hypoglycemia after fructose ingestion and why? What is the

cause of hyperuricemia in this condition?


b) What is the role of glucose 6-phosphate dehydrogenase in red

blood cells?


4. a) A 19 year old girl was referred to a University Medical Centre

because of easy fatigability and poor exercise tolerance in her

extremities. Several muscle biopsy were performed. Microscopic

examination indicated that muscle was filled with vacuoles

containing lipid. Chemical measurements indicated that these

muscles specimen contained greatly elevated amount of

triglycerides but only one sixth as much carnitine as biopsy

specimen obtained from other patient who did not have any

primary muscle disease.

i) What is main intracellular function of carnitine?


ii) Would you expect that the fatty acid -oxidation is impaired in

this patient?


b) Write down complete reaction for synthesis and utilization of ketone



5. Explain the biochemical basis of phenyl ketonuria, alkaptonuria and

maple syrup urine disease. Mention the nutritional strategy to be

adopted for treatment of phenyl ketouria?


6. a) A 32 year old male presents to ENT clinic with complaints of a sore

throat. He reports numerous upper respiratory tract infections over

the last three months. Patient gives a history of intravenous drug

use in the past, but no other significant medical history is given. On

examination, patient is found to have a temperature of 37.8?C

(100.0?F) and is in minimal distress from the sore throat. His

pharynx is erythematous and has numerous white plaques coating

the throat.

There is also prominent cervical lymph node enlargement. His chest

is clear to auscultation and heart is with regular rate and rhythm. A

CD4 T-lymphocyte cell count is performed and is less than 200 cells

per mm3 (normal > 500).

He was diagnosed as a case of secondary infection to HIV infection.


i) HIV is abbreviation of which pathogen?

ii) Which enzyme is required for this pathogen to affect the host



iii) What is the biochemical mechanism that the pathogen uses to


affect the patient cells?

b) For each of the following steps in prokaryotic protein synthesis

(1 to 4) indicate the most appropriate antibiotic (A-J) to inhibit the



i) Transfer of the peptide from the pepitidyl-tRNA to the amino

acyl-tRNA and formation of a peptide bond.

ii) Binding of amino acyl-tRNA from the A-site of the ribosomal


iii) Translocation of the peptidyl-tRNA from the A-site to the P-site.

iv) Interference with the initiation of protein synthesis.

a) Amino glycosides f) Lincosamides

b) Chloramphenicol g) Neomycin

c) Erythromycin h) Puromycin

d) Gentamicin i) Streptomycin

e) Kanamycin j) Tetracycline

7. a) A baby aged 2 months, was admitted with 2 week history of

vomiting and septicemia. On admission he was severely dehydrated

and had circulatory collapse. Following investigations were


Normal range


Na 132 mEq/L (135-145)


K 2.6 mEq/L (3.5-5)


Cl 72 mEq/L (93-108)


HCO3 41.4 mEq/L (22-26)


pH 7.77 ( 7.35-7.45)


pCO2 36 mmHg (35-45)

i) What is your diagnosis?


ii) Is there any compensation?


iii) How does change in blood pH influence distribution of

potassium and chloride ions in intracellular and extracellular




What is the significance of dietary fiber? Find out the caloric

requirement / day of a 10 year old school boy who is moderately

active and his BMR is 400 KCal (energy expenditure for moderate

physical activity is 5 times that of BMR).


8. What are the steps for synthesis and secretion of thyroxin?


This post was last modified on 04 December 2021