Carbohydrates Biochemistry Set 5

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Biochemistry (Carbohydrates And Carbohydrate Metabolism Set 5)

MCQ

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1. The conversion of pyruvate to acetyl CoA
and CO2

A) Depends on the coenzyme biotin

B) Occurs in the cytosol

C) Involves the participation of lipoic acid

D) Is reversible

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2. Reduced glutathione functions in R.B.Cs
to

A) Reduce methemoglobin to hemoglobin

B) Reduce oxidizing agents such as H2O2

C) Produce NADPH

D) Produce NADH

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3. Glucokinase

A) Is widely distributed and occurs in most mammalian tissues

B) Is widely distributed in Prokaryotes

C) None of these

D) Has a high km for glucose and hence is important in the phosphorylation of glucose primarily after ingestion of a carbohydrate rich meal

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4. Which of the following enzyme is not
involved in HMP shunt

A) Glyceraldehyde-3-p dehydrogenase

B) Glucose-6-p-dehydrogenase

C) Transketolase

D) Phosphogluconate dehydrogenase

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5. The free energy change, AG

A) Can only be calculated when the reactants and products are present at 1mol/1 concentrations

B) Is equal to –RT in keq

C) Is directly proportional to the standard free energy change, AG

D) Is equal to zero at equilibrium

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6. The more positive the E0, the greater the
tendency of the oxidant member of that
pair to

A) Lose (or) gain electrons

B) Lose electrons

C) Lose and gain electrons

D) Gain electrons

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7. Which of the following reactions is unique
to gluconeogenesis

A) Phosphoenol pyruvate pyruvate

B) Lactate Pyruvate

C) Glucose-6-phosphate Fructose-6-phosphate

D) Oxaloacetate phosphoenol pyruvate

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8. The synthesis of glucose from pyruvate
by gluconeogenesis

A) Is inhibited by elevated level of insulin

B) Requires oxidation/reduction of FAD

C) Occurs exclusively in the cytosol

D) Requires the participation of biotin

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9. Cori cycle is

A) Both (A) & (B

B) uptake of glycose

C) Synthesis of glucose

D) reuse of glucose

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10. Under standard conditions

A) The free energy change ∆G°, is equal to 0

B) Keq is equal to 1

C) The free energy change, ∆G°, is equal to the standard free energy change, ∆G°

D) The standard free energy change ∆G, is equal to 0

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11. An allosteric enzyme responsible for
controlling the rate of T.C.A cycle is

A) Aconitase

B) Fumarase

C) Malate dehydrogenase

D) Isocitrate dehydrogenase

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12. Phenylalanine is the precursor of

A) Histamine

B) L-DOPA

C) Throxine

D) Tyrosine

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13. How many ATP molecules will be required
for conversion of 2-molecules of Lactic acid
to Glucose

A) 8

B) 4

C) 2

D) 6

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14. The reaction catalysed by phosphofructokinase

A) Is the rate-limiting reaction of the glycolytic pathway

B) Is inhibited by fructose 2, 6-bisphosphate

C) Is activated by high concentrations of ATP and citrate

D) Uses fruitose-1-phosphate as substrate

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15. An uncoupler of oxidative phosphorylation such as dinitropheno

A) Inhibits electron transport without impairment of ATP synthesis

B) Inhibits electron transport and ATP synthesis

C) Specially inhibits cytochrome b

D) Allow electron transport to proceed without ATP synthesis

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16. All of the following statements about the
enzymic complex that carries out the
synthesis of ATP during oxidative
phosphorylation are correct except

A) It can exhibit ATPase activity

B) It is inhibited by oligomycin

C) It is located on the matrix side of the inner mitochondrial membrane

D) ) It can bind molecular O2

17 / 31

17. Which one of the following compounds
cannot give rise to the net synthesis of
Glucose

A) Glycerol

B) Acetyl CoA

C) Lactate

D) α-ketoglutarate

18 / 31

18. Glycogen is present in all body tissues
except

A) Brain

B) Liver

C) Stomach

D) Kidney

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19. The glycolysis is regulated by

A) Pyruvate kinase

B) Hexokinase

C) Phosphofructokinase

D) All of these

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20. Which of the following statements
regarding T.C.A cycle is true

A) It contains no intermediates for GluconeogenesisIt contains no intermediates for Gluconeogenesis

B) It is amphibolic in nature

C) It is an anaerobic process

D) It occurs in cytosol

21 / 31

21. Reduced glutathione functions in R.B.Cs
to

A) Reduce methemoglobin to hemoglobin

B) Produce NADPH

C) Reduce oxidizing agents such as H2O2

D) Produce NADH

22 / 31

22. Which one of the following would be
expected in pyruvate kinase deficiency

A) Increased phosphorylation of Glucose to Glucose-6-phosphate

B) Hemolytic anemia

C) Increased levels of lactate in the R.B.C

D) Decreased ratio of ADP to ATP in R.B.C

23 / 31

23. How many ATPs are produced in the
conversion of phosphoenol pyruvate to
citrate

A) 1

B) 2

C) 4

D) 6

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24. Out of 24 mols of ATP formed in TCA cycle,
2 molecules of ATP can be formed at
“substrate level” by which of the
following reaction

A) Succinic acid→ Fumarate

B) Citric acid→ Isocitric acid

C) socitrate→ Oxaloacetate

D) Succinylcat→ Succinic acid

25 / 31

25. Phenylalanine is the precursor of

A) L-DOPA

B) Tyrosine

C) Throxine

D) Histamine

26 / 31

26. Which one of the following statements
concerning glucose metabolism is correct

A) The conversion of Glucose to lactate occurs only in the R.B.C

B) An elevated level of insulin leads to a decreased level of fructose 2, 6-bisphosphate in hepatocyte

C) Pyruvate kinase catalyses an irreversible reaction

D) Glucose enters most cells by a mechanism in which Na+ and glucose are co-transported

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27. Electron transport and phosphorylation
can be uncoupled by compounds that
increase the permeability of the inner
mitochondrial membrane to

A) Protons

B) Electrons

C) Uncouplers

D) All of these

28 / 31

28. In presence of the following cofactor,
pyruvate carboxylase converts pyruvate
to oxaloacetate

A) ATP, Protein and CO2

B) CO2

C) CO2 and ATP

D) Protein

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29. For conversion of oxaloacetate to
phosphoenol pyruvate, high energy
molecule is required in the form of

A) None of these

B) GTP (or) ITP

C) ITP only

D) GTP only

30 / 31

30. The reaction catalysed by phosphofructokinase

A) Is activated by high concentrations of ATP and citrate

B) Uses fruitose-1-phosphate as substrate

C) Is inhibited by fructose 2, 6-bisphosphate

D) Is the rate-limiting reaction of the glycolytic pathway

31 / 31

31. Compared to the resting state, vigorously
contracting muscle shows

A) Decreased oxidation of pyruvate of CO2 and water

B) Decreased concentration of AMP

C) A decreased NADH/NAD+ ratio

D) An increased conversion of pyruvate to lactate

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The average score is 58%

Carbohydrates Biochemistry Set 5

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