1^ST MBBS MCQ-test Feb08

01. Which physical property that allows lipids to form membranes:

A.      They polymerize readily.

B.       Inherent flexibility.

C.       They are amphipathic. They have hydrophobic tails and hydrophilic heads.

D.      Tight binding to proteins.

E.       High degree of reactivity.

 

02. the following compounds are esterified  With Membrane phospholipids except

 

A.      choline

B.      serine

C.      inositol

D.      ethanolamine

E.      ribose

 

03. Aspirin (acetylsalicylate) affects prostaglandin synthesis form arachidonic acid by inhibiting the cyclooxygenase activity of prostaglandin H synthase. This type of inhbition is

A.      covalent modification.

B.      competitive.

C.      non-competitive.

D.      uncompetitive.

E.      proteolysis.

 

04. Which of the following is an acidic amino-acid?

A.      ascorbic acid

B.      acetic acid

C.      aspartic acid

D.      lysergic acid

E.      diaminopimelic acid

 

05. Before fats can be acted upon by the digestive enzymes, they must be:

A.      Nutralized

B.      Esterified

C.      Emulsified

D.      Denatured

E.      Hydrolysed

 

06. For functional activity, both cytochrome oxidase and superoxide dismutase require biological forms of

A.      cobalt.

B.      copper.

C.      magnesium.

D.      Molybdenum

E.      selenium

 

07. The immediate product of the degradation of glycogen by phosphorylase:

A.      fructose-6-phosphate

B.       fructose-1,6-bisphosphate

C.       glucose

D.      glucose-6-phosphate

E.       glucose-1-phosphate

 

08. The following enzymes are regarded as gluconeogenic EXCEPT:

A.      Glucokinase

B.       Glucose-6-phosphatase             

C.       Fructose 1,6 diphosphatase

D.      Pyruvate carboxylase

E.       Phosphoenolpyruvate carboxykinase

09. In liver, the metabolism of acetyl-CoA can lead to a NET synthesis of all of the following EXCEPT

A.      cholesterol.

B.      3-hydroxybutyrate

C.      oxaloacetate.

D.      oleate.

E.      cholate.

 

10. Absorption of which one of the following aminoacids is defective in Hartnup's disease:

A.      glycine

B.      lysine

C.      leucine

D.      tyrosine

E.      tryptophan

 

11. The function of the urea cycle is to

A.      convert amino acids into ketoacids

B.      convert ketoacids into amino acids

C.      convert ammonia into a less toxic form

D.      enure that urine does not precipitate

 

12. The formation of carbamoyl phosphate to begin pyrimidine biosynthesis occurs in the

A.      mitochondrion.

B.      cytosol.

C.      nucleus.

D.      endoplasmic reticulum

E.      lysosome.

 

13. The principal store of metabolic energy available during long- term fasting or starvation is

A.      smooth muscle glycogen.

B.      liver glycogen.

C.      skeletal muscle protein.

D.      adipose tissue triacylglycerol.

 

14. Dental carries caused by the local production of acids by bacteria is inhibited by

A.      calcum

B.      bromine

C.      fluoride

D.      selenium

E.      zinc

 

15. In response to metabolic acidosis, biosyntheis of glutaminase increases in:

A.      brain

B.      liver

C.      intestine

D.      kidney

E.      muscle

 

16. Biochemical mechanisms for regulating enzyme activity involve all of the following EXCEPT:

A.      converting activated enzymes back to zymogens

B.      phosphorylation of amino acid side chains

C.      cleavage of peptide bonds

D.      dissociation of subunits

E.      allosteric interactions

 

17. Biological membranes contain all but one of the following major classes of biomolecules:

A.      carbohydrate

B.      fats

C.      proteins

D.      nucleic acids

 

18. Oxygen binding to hemoglobin increases as the

A.      2,3-diphosphoglycerate level is reduced.

B.      temperature is increased.

C.      CO₂ level is increased.

D.      pH is reduced.

 

19. A generic name of all the enzymes that catalyze the oxidation reactions in the TCA cycle is

A.      oxidase

B.      reductase

C.      dehydrogenase

D.      synthase

E.      dehydrase

 

20. Which process requires selenium?

A.      Reduction of lipid peroxides by glutathione peroxidase

B.      Scavenging of reactive hydroxyl radicals

C.      Reduction of dehydroascorbic acid to Vitamin C

D.      Repair of 8-hydroxylguanosine in DNA

E.      Conversion of superoxide to hydrogen peroxide and molecular oxygen by superoxide dismutase

 

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Answer key to 1^ST MBBS MCQ-test: Jan, 2008

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