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Q.1-20 multiple choice questions .

Q-2- a) Describe the reaction catalyzed by phosphofructo kinase-1 enzyme and explain how is it regulated?                                                                           

b) Give a diagrammatic representation of sites of ATP formation and inhibitors of the mitochondrial Electron Transport Chain.                                                                                                                      

Q.3- a) Describe various mechanisms of enzyme inhibition. Mention the clinical uses of enzyme inhibitors.                                                                  

b) Describe the steps of urea formation and discuss the mechanism of ammonia  intoxication of brain.                                                                          

Q.4-  a) Explain the causes, clinical manifestations and laboratory diagnosis of-

 i) Albinism                 

ii) Von Gierke’s disease                                  

b) Calculate the energy yield from the complete oxidation of one molecule of  glucose under aerobic conditions.                                                      

Q.5- a) Describe the steps of beta oxidation of fatty acids. What is the clinical  significance of this pathway?                                                             

b) Give a diagrammatic representation of structure of a lipoprotein molecule.

c) Discuss the causes, and effects of denaturation of proteins.       

Q.6- Write short note on-

a) Vitamin C deficiency

b) Rancidity

c) Lipotropic agents                                                                           

d) Cori’s cycle                                                                         

Multiple Choice questions

Q.1- Acetyl co A carboxylase enzyme requires ————— as a coenzyme.

a) FMN                                               

b) Biotin  

c) NAD+                                          

d) TPP                   

Q.2- All are intermediates of glycolysis except-

a) Glucose-6 phosphate                       

b) Fructose 1, 6 bisphosphate         

c) Fructose-6- phosphate

d) Glycerol – 3- phosphate 

 Q.3- In the de novo synthesis of fatty acids, Acetyl co A first gets converted to –

a) Mevalonate                                     

b) Malonyl co A      

c) Malonate

d) D-Methyl malonyl co A 

Q.4- All of the following compounds are synthesized from Tyrosine except-

a) Melanin                                                      

b) Catecholamines                                          

c) Thyronine

d) Creatinine                           

Q.5- Which of the following is predominantly required for coagulation of blood-

a) Sodium                                            

b) Calcium         

c) Potassium                                 

d) Magnesium                        

Q.6- Hemoglobin is a

a) Nucleoprotein                                 

b) Glycoprotein                                  

c) Phosphoprotein

d) Chromo protein                

Q.7- Cholesterol is a precursor of all except-–

a) Bile pigment                                    

b) Sex hormones                                

c) Vitamin D

d) Corticosteroids                 

Q.8- Phospholipase A2 can be found in –

a) Pancreatic juice                               

b) Gastric juice                                   

c) CSF

d) Amniotic fluid                  

Q.9-The disease resulting from vitamin B12 deficiency is-

a) Pernicious anemia                           

b) Night blindness                              

c) Beri-Beri

d) Scurvy                                

Q.10- Serotonin is synthesized from which of the following amino acid?

a) Phenylalanine                               

b) Glycine                                          

c) Tryptophan

d) Methionine                        

 Q.11- Prostaglandins are synthesized from –

a) Arachidonic acid                             

b) Stearic acid                                    

c) Palmitic acid

d) Oleic acid                           

Q.12- The biochemical defect in Niemann–pick disease, is deficiency of-

a) Glucose-6 –phosphate dehydrogenase       

b) Hexosaminidase –A                                   

c) Glucose-6-phosphatse

d) Sphingomyelinase   

Q.13- In an enzyme assay, in which the substrate concentration is much higher than Km, the rate

a) Approaches half Vmax                

b) Shows first order kinetics              

c) is independent of enzyme concentration

d) shows zero order kinetics 

 Q.14- Formation of UDP Galactose from Galactose-1-P is catalyzed by-

a) Hexokinase                                     

b) Aldolase                                         

c) Galactokinase

d) Galactose-1-P Uridyl transferase 

Q.15- All are found in obstructive jaundice except-

a) Conjugated hyperbilirubinemia       

b) Bilirubinuria                                   

c) Raised Alkaline phosphatase

d) Dark tarry stools                

Q.16- The excretion of which of the following compound is greatly increased in urine in Carcinoid syndrome-

a) Indole acetic acid                           

b) 5- hydroxy Tryptamine                  

c) 5- hydroxy tryptophan

d) 5- Hydroxy Indole acetic acid       

Q.17- The iso electric p H of which of the following proteins is 4.6-

a) Zein                                                 

b) Casein                                            

c) Keratin

d) Myosin                                       

Q.18- The reaction catalyzed by- Lactate dehydrogenase is-

a) Pyruvate <—————————–> Lactate

b) Pyruvate—————————–>Oxaloacetate

c)  Pyruvate—————————-> Acetyl Co A

d) Pyruvate—————————->Acetaldehyde                                 

Q.19- The key regulatory enzyme of HMP pathway is-

a) G- 6-phosphate dehydrogenase      

b) Transaldolase                                 

c) Transketolase

d) G-6-phophatase               

Q.20- Pellagra is caused by nutritional deficiency of-

a) Vitamin B12                                     

b) B6                                                   

c) Niacin

d) Folic acid                          


  Model Answers- Paper -I

Q.1- Multiple Choice Questions-





















Q2- a) Reaction catalyzed by phosphofructo kinase-1 enzyme – This is the rate limiting enzyme of glycolysis. It catalyzes the formation of Fr 1,6 bisphosphate from Fr-6-p.It is regulated by substrate concentration, product inhibition, allosteric modification and by induction or repression. Insulin favours while glucagon and catecholamines inhibit glycolysis. Hypoxia also stimulates glycolysis. Allosterically fr-2,6 bisphosphate acts as a positive modifier while ATP acts as negative modifier.

Details are needed

b)  A diagrammatic representation of sites of ATP formation and inhibitors of the mitochondrial Electron Transport Chain- The four complexes of ETC are to be represented showing the entry of reduced coenzymes, and the sites of ATP formation . The sites of site specific inhibitors are to be shown.

Q.3- a) Mechanisms of enzyme inhibition- Enzymes can be inhibited by-

a)  Competitive inhibition

b) Non Competitive inhibition

c) Un Competitive inhibition

d) Allosteric inhibition

Clinically enzyme inhibitors are used as drugs for the treatment of various diseases. The role of ACE inhibitors  for the treatment of hypertension, Methotrexate and various other  for cancers, Statins for hypercholesterolemia, Sulphonamides, Trimethoprim and Penicillin as antibacterial agents etc are to be referred mentioning the inhibition of the specific enzymes.

3-b) Steps of Urea formation- Urea is formed in liver from Ammonia and CO2, which condense together to form Carbamoyl- phosphate in the presence of CPS-I enzyme. Carbamoyl- phosphate further condenses with ornithine to form Citrulline. Citrulline condenses with aspartic acid to form Argino succinic acid which is subsequently cleaved to form Arginine and fumarate. Fumarate is converted to malate, then to Oxaloacetate, which is transaminated to form Aspartate. Aspartate can re enter the cyclic pathway. On the other hand Arginine is cleaved to form Ornithine and urea. Ornithine can be reutilized for the continuation of the cycle.

Reactions are to be shown

Ammonia is toxic to brain, as it depletes Alpha keto glutarate, and glutamate resulting in depression of TCA cycle and reduced formation of GABA the inhibitory neurotransmitter. Glutamine level is increased which is transported out in return for Tryptophan. Tryptophan is a precursor for serotonin, an excitatory neurotransmitter. All these result in energy depletion due to depression of TCA cycle and hyperexcitaion due to excessive Serotonin production. Convulsions and coma are the signs on ammonia intoxication. Death occurs in untreated cases.

Q.4- a) i) Albinism- is a disorder of Tyrosine metabolism. There is deficiency of Tyrosinase enzyme; as a result there is impaired formation of Melanin. The affected patients show depigmentation of iris, skin and hair. Based on the type of defect, Albinism can be ocular, occulocutaneous or partial. Diagnosis is made by clinical manifestations and by estimation of Tyrosinase enzyme in cultured cells. No permanent cure only symptomatic treatment can be imparted.

ii) Von-Gierke’s disease- It is a type 1 glycogen storage disease. The defect lies in the deficiency of Glucose-6 phosphatase enzyme. There is impaired glycogen degradation and hence normal glycogen gets abnormally accumulated in liver, intestine and kidney. Hypoglycemia is a characteristic finding. Short stature, protuberant abdomen, pallor, bleeding tendencies and impairment of liver and kidney functions are typical of this disease. Hyperuricemia, hypoglycemia and lactic acidosis are diagnostic. No permanent cure, only symptomatic treatment is given.

Details are needed

b) Energy yield from the complete oxidation of one molecule of glucose under aerobic conditions-38 ATPs are produced from the complete oxidation of one molecule of Glucose. The details of energetic of Glycolysis, Pyruvate dehydrogenase complex and the oxidation of Acetyl co A in TCA cycle are to be mentioned.8 ATPs in glycolysis, 6 in PDH complex and 24 ATPs in TCA cycle are produced making a total of 38 ATPs.

Q.5-a) Steps of beta oxidation of fatty acids-

Activation to form Acyl co A, internalization to mitochondrial matrix through carnitine shuttle and the subsequent steps of beta oxidation in the form of dehydrogenation, hydration, dehydrogenation and thiolytic cleavage are to be mentioned. The total energy yield is to be explained. The clinical significance lies in medium chain acyl co A dehydrogenase deficiency and carnitine deficiency producing hypoglycemia due to imbalance between demand and supply of energy.

b) Structure of lipoprotein molecule- Lipoproteins are conjugated proteins for the transportation of lipids. The hydrophilic exterior of lipoprotein is made by apoproteins, free cholesterol and by phospholipids while the hydrophobic core is constituted by triglycerides, cholesteryl ester etc. All have to be represented by a clean diagram.

c) Denaturation- The process of disruption of the secondary, tertiary or quaternary structure if present of proteins is called Denaturation. The primary structure remains intact. Application of heat, strong acids, strong alkalies, heavy metal salts and physical factors like vigorous shaking and freezing can bring about Denaturation. The Denaturation in most cases is irreversible but it can be reversible also as in iso electric p H pecipitation or denaturation of Ribonuclease in the presence of urea.

 Protein loses its biological property on Denaturation. There is total functional loss on Denaturation. Details are to be provided for the types and effects of Denaturation.

 Q.6- a) Vitamin C deficiency is manifested in the form of scurvy, which is characterized by bleeding tendencies, bony changes and microcytic hypochromic anemia. Causes, detection of deficiency and treatment are to be mentioned

 b) Rancidity- It is the unpleasant smell and taste given by fats when kept for a long time or exposed to air. It is due to partial hydrolysis or oxidation of fats producing fatty aldehydes. Anti oxidants can be added to prevent rancidity. Brief reference of lipid peroxidation is also required to be mentioned.

c) Lipotropic agents- Essential fatty acids, choline. Betaine, methionine, vitamin B6, B12 and folic acid are called as lipotropic agents. They are so called lipotropic agents as they prevent the deposition of fats in liver cells and promote fat mobilization from liver to peripheral tissues. Deficiency of these factors produces fatty liver.

d) Cori’s cycle- Transportation of  lactate from muscles through blood to liver for conversion to glucose and transportation of glucose from liver  back to muscles for utilization in the glycolytic pathway for energy production and production of lactate  which is transported to liver again and again in the same way, this constitutes cori’s cycle. It is meant for disposal of waste product of muscle i.e. lactate for glucose production. Accumulation of lactate in muscles produces fatigue,



Paper II

Q.1- 20 multiple choice questions ,                    

Q.2-  a) What is the significance of maintenance of p H in body? Give a brief   account of role of kidneys in the regulation of acid and base balance of the  body.                                                                                                  

b)  Briefly discuss the role of ATP in the biological   system.          

c) Discuss the biochemical basis of hyperuricemia in HGPRTase deficiency.

Q.3-a) Discuss the salient features of Transcription of DNA.                  

b) Briefly discuss about post translational modifications.                  

c) What are the possible causes of DNA damage? How is this damage repaired?   

 Q.4-  a) Give a detailed account of Respiratory acidosis, mentioning the possible  causes, alterations in laboratory profile, compensation by the regulatory    mechanisms and the consequences in untreated cases.                                                                                                                                                                     

b) Describe the role of Renin -Angiotensin system in the maintenance of water and electrolyte balance of the body;                                                         

Q.5-  a) Discuss the causes of Protein energy malnutrition. What are the possible risk factors associated with it and how can this be treated?       

b) A 20 year-old drug addict has reported to emergency complaining of fever,   cough,  diarrhea and weight loss from the last few months. He is too weak to walk. There is a suspicion of HIV infection. How will you proceed for the diagnosis? What seems to be the possible cause for HIV infection in this patient? What are  the various modes of transmission of HIV infection?                

Q.6- Write short note on-

 a) Biochemistry of cancer cells          

 b) Galactose tolerance test

 c) Thin layer chromatography                                                          


Multiple Choice questions

Q.1- In protein synthesis which out of the following is a termination codon?

a) UAU                                              

b) UAC       

c) UGA                                       

d) UGG                       

 Q.2- A promoter site on DNA –

a) is present upstream to the start site           

b) is present on the coding strand     

c) Initiates transcription              

d) All of the above     

Q.3- All are true for DNA polymerase except one-

a) Has exonuclease activity

b) Works only in 5`to 3` direction

c) Edits as it synthesizes

d) Synthesizes RNA primer to initiate DNA synthesis.       

Q.4- Which of the following result is provided by Western Blot Analysis

a) Detects DNA molecules             

b) Detects Protein molecules             

c) Detects RNA molecules

d) Determines chromosomal structure

Q.5- Which of the following is an anticancer drug?

a) 5- methyl thymidine                      

b) Ribose phosphate                           

c) Ara C

d) PRPP (5- phosphoribosylpyrophosphate)

Q.6- All are true regarding Nephrotic syndrome except-

a) Hypoglycemia                               

b) Proteinuria          

c) Edema                          

d) Hypoproteinemia    

 Q.7- Urinary finding in Starvation is

a) Glycosuria                                    

b) Ketonuria                                       

c) Proteinuria

d) oliguria        

 Q.8- What is true of Diabetes Insipidus?

a) High specific gravity of urine         

b) Oliguria                                          

c) Deficiency of ADH hormone

d) Glycosuria

Q.9- LDH is increased in-

a)Acute MI                                         

b) Hemolytic anemia                          

c) Liver diseases

d) All of the above.  

Q.10- Approximately ———– of bile acids are excreted in feces per day

a) 2 00 G                                            

b) 200 mg

c) 400 G                                             

d) 400 mg               

Q.11- Essential fatty acids can be synthesized in-

a) Human beings                              

b) Animals                                          

c) plants

d) None of the above 

Q.12- A condition where the amount of nitrogen lost from the body exceeds the dietary intake is called as:

a) Negative nitrogen balance              

b) Nitrogen equilibrium      

c) Positive nitrogen balance                

d) Uremia.                  

Q.13- Which of the following sugar is found in RNA?

a) 2- deoxy Ribose                              

b) 3-deoxy Ribose  

c) D- Ribose                            

d) D- Xylulose                       

Q.14- Congenital absence of Adenosine deaminase causes-

a) Immunodeficiency                         

b) Hyperglycemia                              

c) Hyperuricemia

d) Hyperoxaluria       

Q.15- All are nucleosides except-

a) Cytosine                                        

b) Guanosine                                      

c) Inosine

d) Adenosine             

Q.16- An anxious, nervous female was breathing rapidly. What do you expect the acid base status of the body?

a) Metabolic acidosis                      

b) Metabolic alkalosis      

c) Respiratory acidosis                  

d) Respiratory Alkalosis 

Q.17- Periods of prolonged starvation will produce what type of acid base alteration in the body?

a) Metabolic acidosis                          

b) Metabolic alkalosis                        

c) Respiratory acidosis

d) Respiratory Alkalosis

Q.18- All are inhibitors of protein synthesis except-

a) Streptomycin                                               


c) Oligomycin

d) Tetracycline                      

Q.19- All of the following are observed in high fibre diet except-

a) Reduced incidence of constipation

b) Decrease in blood cholesterol

c) Increased frequency of hyperglycemia

d) Decreased risk of colon cancer                                                       

Q.20-If there is an increased concentration of glucose in urine, the most likely cause could be

a) Starvation                                        

b) Alcoholism                                     

c) Diabetes mellitus

d) Hepatitis          


Model Answers- Paper- II

 Q.1-Multiple choice questions






















Q.2-a) Significance of maintenance of p H in the body- p H maintainenance is required for the proper functioning of proteins, enzymes, DNA, nerve conduction ,muscle contraction, as well as for the flow of substances across the membranes. Blood buffers, lungs and kidney play a significant role in the maintenance of body p H. Kidneys promote excretion of H+ and reabsorption of bicarbonate ions depending on acid base status of the body. The bicarbonate, phosphate and ammonia mechanisms are required to be explained giving diagrammatic representations.

b) Role of ATP in the biological system- ATP is considered the energy currency of cell. Various examples of exergonic reactions are to be mentioned. Sources of ATP i.e. from oxidative phosphorylation and substrate level phosphorylation are to be mentioned.

c) Biochemical basis of hyperuricemia in HGPRTase deficiency- HGPRTase deficiency is manifested as Lesch Nyhan syndrome. Hyperuricemia is due to non utilization of PRPP which in turn is used for Denovo synthesis of purine nucleotides. Purines can not be utilized by Salvaged pathway; hence they are catabolized to form uric acid. Excess synthesis and catabolism of purines is the cause of hyperuricemia in this defect.

 Q.3- Salient features of Transcription of DNA

I) Transcription process includes initiation, elongation and termination.

2) There are specific sites on DNA that act as start signals for initiation process. The RNA polymerase attaches at the promoter site on the template strand.

3)The region between promoter and terminator  sites on DNA site is called as Transcription unit, which is transcribed in to mRNA.

4) Bacterial RNA polymerases differ from eukaryotic  RNA polymerases.

5) One of the strand acts as a template and the base pairing rule is followed.

6) There is no proof reading, hence less fidelity is there.

7) Specific signals are recognized for termination by termination protein, the Rho    factor. The termination can also be Rho independent.

8) The primary transcript thus formed undergoes post transcriptional modifications.

b) Post translational modifications- The mature functional protein is formed by the post translational processes, which include the following processes-

1) Proteolytic cleavage

2) Modification of the amino acids

3) Sub unit aggregation etc. are to be discussed with suitable examples. 

c) DNA damage and repair

Following are the possible causes of DNA damage –

1) Misincorporation of deoxy ribonucleotides during replication

2) Spontaneous Deamination of bases

3) From X- Rays that cause nicks in the DNA

4) From UV radiations that cause Thymine dimer formation

5) From various chemicals that interact with the DNA

Mechanisms of repairSeveral methods are there –

1)      Excision repair

2)      Photo reactivation

3)      Recombinational repair

4)      Mismatch repair

Q.4-a) Respiratory acidosis

Primary excess of carbonic acid produces respiratory acidosis. Respiratory acidosis may result from bronchopneumonia or status asthmaticus. Depression of respiratory centre by sedatives or narcotics; chronic obstructive pulmonary diseases etc cause difficulty in breathing resulting in retention of carbonic acid. Renal compensation occurs by excretion of more H+  and retention of bicarbonates.

Alterations in p H, blood gas analysis etc to be mentioned.

Treatment depends on the primary cause.

 Details are needed

b) Role of Renin -Angiotensin system in the maintenance of water  and electrolyte balance of the body- Renin is a proteoltic enzyme released from the kidney. It is released in response to the fall in sodium ion concentration, Hypovolemia, hypotension and a fall in intra cellular calcium ion conc., All these factors  stimulate the release of Renin from J.G. cells to blood. The action of Renin is mediated through the release of Angiotensin I from Angiotensinogen. Angiotensin I  is then converted to Angiotensin II and then to Angiotensin III. Both the later Angiotensins cause the release of Aldosteron from the Adrenal cortex, which causes the absorption of Sodium ions to restore the blood pressure and the fluid volume. The interdependence of Renin- Angiotensin system and the Aldosteron is to be discussed. The clinical significance and the use of ACE inhibitors for the treatment of Hypertension are to be discussed.

Q.5- a) Protein energy malnutrition

At one end of the spectrum is Marasmus which results from a continued and the severe deficiency of both dietary energy and proteins (primary calorie in adequacy and Secondary protein deficiency). At the other end of the spectrum is Kwashiorkor, where isolated deficiency of proteins along with adequate calorie intake is seen.

A brief description of the causes, clinically symptoms and laboratory findings is to be given. The possible treatment is also required to be mentioned.

b) Transmission of HIV- The various routs like the blood, placenta, sex etc are to me mentioned. The cause of HIV infection in this patient seems to be drug abuse.

Q.6-a) Biochemistry of cancer cells- cancer cells are characterized by three important properties-Diminished or unrestricted growth, Capability of invasion of local tissues and capability of spread to distant places by metastasis . The characteristics of cancer cells – the morphological and biochemical changes are to be discussed.

b) Galactose tolerance test- It is an index of impaired liver functions. When galactose load is given , it is  exclusively metabolized in liver and is converted to glucose The rate of utilization is proportional to functional liver cell mass. Details of procedure and observations in cirrhosis of liver and infective hepatitis are to be mentioned.

c) Thin layer chromatography

This is another version of the liquid- liquid chromatography. A thin layer of the silica gel is spread on a glass plate, biological sample is applied as a small spot .T he plate is placed in a trough containing the solvent.. The stationary water phase is held on the silica gel and the mobile phase of non polar solvent moves up. In the case of TLC it takes only 3-4 hours for the separation of the substances in comparison to Paper chromatography which takes 14-16 hours, that is a distinct advantage for TLC.




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