Mansoura Faculty of medicine
Medical Biochemistry Department
Quiz (2)
Second year
(Carbohydrate Metabolism)
Student name:……………………………………
score :10
section: …………………………….
Student number:…………………..Time : 10 min
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I)
Choose the best answer:
1- Which of the following metabolites can NOT be a substrate for gluconeogenesis?
a) Succinate
b) Acetate c) Lactate
d) Alanine
2- Binding of AMP to glycogen phosphorylase leads to:
a) Activation of the enzyme
b) Inhibition of the enzyme
c) Polymerization of the enzyme
d) AMP does not affect the enzyme
3- The activity of oxidative irreversible reaction (phase I) of hexose
monophosphatepathway is very low in:
a) Adipose tissues
b) RBCs c) Skeletal muscles d) Adrenal cortex
4- In the citric acid cycle, carbon dioxide is derived from:
a) Succinate and Fumarate
b) Malate and Oxalacetate
c) Citrate and Cis-aconitate
d) Isocitrate and α-ketoglutarate
5- Patients suffering from galactosemia are placed on a galactose free diet.
Galactose,however, is required by the body to form brain cerebrosides. How is
galactose formed inpatients on a galactose free diet?
a) Epimerization of UDP-glucose
b) Reaction of a 5- and a 4-carbon sugar catalyzed by transketolase
c) Oxidation of sorbitol
d) Epimerization of glucose-1-phosphate
II)
Complete the following sentences:1) Amylase enzyme is endoglucosidase so its end product is …………….……………….
2) Glycogen primer is …...................................................................................……...
3) Hexokinase enzyme act on glucose in……………………..………………..................&
its product is ….………………………………...
4) Fructose intolerance is due to ……………………………………………………………………….
5) Arsenate can affect glycolysis by ……………………………………………………………………
Mansoura Faculty of medicine
Medical Biochemistry Department
Quiz (2)
Second year
(Carbohydrate Metabolism)
Student name:……………………………………
score :10
section: …………………………….
Student number:…………………..Time : 10 min
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I)
Choose the best answer:
1- Anaplerotic reaction of Kreb`s cycle involve all these compounds EXCEPT:
a) Aspartic acid b) Glutamic acid c) Acetate
d) Pyruvate
2- The obligatory reaction of Cori cycle that occurs in both liver and muscles
iscatalyzed by:
a) Hexokinase b) Pyruvate kinase
c) Glucose -6-phosphatase
d) Lactate dehydrogenase
3- FAD is required as a co-enzyme for the following EXCEPT:
a) Conversion of pyruvate to acety CoA
b) Conversion of succinate to fumarate
c) Conversion of dihydroxy acetone phosphate to glyceraldehyde-3-phosphate
d) Conversion of α–ketoglutarate to succinyl CoA
4- In the process of glycolysis, several different types of reactions take place.
Which ofthe following statements relating to them is correct?
a) All of the intermediate reactants derived from glucose are phosphorylated
b) Two of the reactions are irreversible
c) Four of the reactions involve the net hydrolysis of ATP
d) Three of the reactions are catalyzed by specific kinase
5- About pentose phosphate pathway all these statements are true EXCEPT:
a) It is the main source of NADPH
b) G-6-P dehydrogenase and lactonase are regulatory enzymes of this pathway
c) One molecule of G-6-P is converted to one molecule of ribose-5-P, 2
NADPH.H+ and one molecule of CO2
d) In skeletal muscles, glucose 6 phosphate dehydrogenase is highly active
II)
Complete the following sentences:1- Facilitative diffusion of glucose in RBCs occurs by ……………………..…………..
2- Glycogen primer is composed of ……………………………………………………..........
3- Hexokinase enzyme is regulated by ………………………………………………………..
4- Iodoacetate can inhibit glycolysis by ………………………………………………..…….…
5- Essential reactive hypoglycemia is due to …………………………………………………
Mansoura Faculty of medicine
Medical Biochemistry Department
Quiz (2)
Second year
(Carbohydrate Metabolism)
Student name:……………………………………
score :10
section: …………………………….
Student number:…………………..Time : 10 min
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I)
Choose the best answer:
1- Regulation of citric acid cycle occurs at each of the following enzymes EXCEPT:
a) Citrate synthetase
b) Isocitrate dehydrogenase
c) Aconitase
d) α-ketoglutarate dehydrogenase
2- Which one of the following is a positive allosteric regulator for gluconeogenesis :
a) Adenosine monophosphate (AMP)
b)Acetyl CoA
c) Adenosine diphosphate (ADP)
d) Fructose-2,6-diphosphate
3- Which of the following enzymes functions in both glycolysis &gluconeogenesis:
a) Pyruvate carboxylase
b) Pyruvate kinase
c) Glyceraldehydes-3-phosphate dehydrogenase d) Glucose-6-phosphatase
4- Which of the following human tissues contains the greatest amount of
bodyglycogen?
a) Liver
b) Kidney
c) Skeletal muscle
d)Adipose tissue
5- Reactive hypoglycemia may be due to EXCEPT:
a) Galactosemia b) Starvation
c)Drug-induced usually due to insulin
d) Hereditary fructose intolerance
II)
Complete the following sentences:-
1- Facilitative diffusion of glucose in brain occurs by ………………………….…………………
2- Active form of glycogen synthase is ……………………………………………………………………
3- Glucokinase enzyme acts on glucose in ……………...... & its product is……………………
4- Flouride can inhibit glycolysis at ……….................….so can be used in prevention
of ……………………………………………………………………………………………………………………
5- Favism is …………………………............... due to ………………………………………………………
Mansoura Faculty of medicine
Medical Biochemistry Department
Quiz (2)
Second year
(Carbohydrate Metabolism)
Student name:……………………………………
score :10
section: …………………………….
Student number:…………………..Time : 10 min
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I)
Choose the best answer:
1- The activity of pyruvate dehydrogenase and pyruvate carboxylase is affected by:
a) Pyruvate
b) Acetyl CoA c) ATP
d)ADP
2- Glucose is phosphorylated by both glucokinase (GK) and hexokinase
(HK),glucokinase has high KM while hexokinase has low KM, So:
a) GK is active at low blood glucose levels.
b) GK is active at high blood glucose levels.
c) Gk is important to the liver at low blood glucose levels
d) Hk is important to the liver at high blood glucose levels
3- Which is an unlikely metabolic fate of glucose-6-phosphate in muscle?
a) Conversion to fructose-6-phosphate
b) Conversion to glucose-1-phosphate
c) Splittedto dihydroxyacetone phosphate and glyceraldehydes-3-phosphate
d) Hydrolysis to glucose
e) Conversion to lactate
4- An allosteric enzyme responsible for the rate of citric acid cycle is:
a) Pyruvate dehydrogenase
b) Aconitase
c) Isocitrate dehydrogenase
d) Citrate dehydrogenase
5- The substrate for aldolase is:
a) G-6-phosphate b) F-6-phosphate c) F-1 phosphate d) Phosphoglycerate
II)
Complete the following sentences:1- Facilitative diffusion of glucose in heart occurs by ………………………………………..
2- Inactive form of glycogen synthase is ………………………………………..…………………
3- Glucokinase is regulated by …………………………………………………………………..……..
4- 2, 3 DPG is produced in …………. by the help of enzyme …………………………………
5- Glucosamine 6p is synthesized from ………………………. By ………………………….
reaction.
Mansoura Faculty of medicine
Medical Biochemistry Department
Quiz (2)
Second year
(Carbohydrate Metabolism)
Student name:……………………………………
score :10
section: …………………………….
Student number:…………………..Time : 10 min
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I)
Choose the best answer:
1- An enzyme not involved in glycolysis is:
a) Aldolase b) Enolase c) Pyruvte carboxylase d)Phosphoglyceromutase
2- Glycolysis will be immediately inhibited in a cell in which:
a) ATP is not recycled back to ADP and Pi
b) The citric acid cycle is inhibited for want of NAD+
c) The electron transport chain is poisoned with cyanide
d) The oxygen concentration is below the km of cytochrome oxidase
3- Hypoglycemia is caused by a deficiency of each of the following enzymes
EXCEPT:
a) Fructose 1,6biphosphatase.
b) Glucose 6-phosphatase
c) Pyruvate carboxylase
d) Pyruvate dehydrogenase
4- Which of the following pair of enzymes is required for the process
ofgluconeogenesis?
a) Fructose-1,6-biphosphatase and pyruvate carboxylase
b) Glucose-6-phosphatase and phosphofructokinase-1
c) Glucose-6-phosphatase and pyruvate dehydrogenase
d) Phosphoenolpyruvatecarboxykinase and glucokinase
5- Pyruvate dehydrogenase complex includes all the following EXCEPT:
a) It is inhibited by arsenite and mercuric ions
b) It is responsible for oxidative decarboxylation of pyruvate
c) It is activated by decreased insulin/glucagon ratio
d) It is inhibited by kinase enzyme through increased NADH/NAD ratio
II)
Complete the following sentences:1- Facilitative diffusion of glucose in skeletal muscles occurs by ………………………..
2- Active form of phosphorylase is ……………………………………………………………………..
3- The first step in glucose oxidation in glycolysis occurs by ……………………………….
4- During sprinting the glycolysis is ………………..……..while during marathon
glycolysis is ………………….…
5- Galactosemia causes …………..……………………. hypoglycemia
Mansoura Faculty of medicine
Medical Biochemistry Department
Quiz (2)
Second year
(Carbohydrate Metabolism)
Student name:……………………………………
score :10
section: …………………………….
Student number:…………………..Time : 10 min
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I)
Choose the best answer:
1- The pentose phosphate pathway produces all EXCEPT:
a) NADPH,H that may be used for F.A. synthesis
b) Ribose-5-P that may be used for synthesis of nucleotides and nucleic acid
c) Compounds that are intermediates of glycolysis
d) Reduced glutathione
2- The pyruvate dehydrogenase complex:
a) Is activated by phosphorylation by protein kinase
b) Is located in the cytoplasmic space
c) Produces an activated acetyl group from pyruvate
d) Requires ATP as a co-enzyme
e) Requires biotin as a prosthetic group
3- Hypoglycemia is caused by a deficiency of each of the following enzymes
EXCEPT:
a) Fructose 1,6biphosphatase.
b) Glucose 6-phosphatase
c) Phosphoenolpyruvatecarboxykinase
c) Pyruvate dehydrogenase
4- Which one of the following compounds is required for acetyl CoA to enter the
citricacid cycle?
a) Isocitrate b) Oxaloacetate c) Malate d) Pyruvate
5- Oxidation of one mole of glucose by glycolysis, NADH.H+ is formed during
thesynthesis of which of the following metabolites:
a) Glucose-6p b) Pyruvate c) Fructose-6-p
d) 1,3 biphosphoglycerate
II)
Complete the following sentences:1- Facilitative diffusion of glucose in intestinal brush border occurs by …………….
2- Inactive form of phosphorylase is………………………………………………………………….
3- phosphofrutokinase is allosterically activated by …………………… & inhibited by
………………………………………………………………………………………………………………………
4- Phosphorylation &dephosphorylation of pyruvate dehydrogenase complex
can be interconverted by the action of two enzymes which are kinase that
activated by ………………………………………..………………………….………………….. &
phosphatase that activated by ………………….………………………………………………
5- Reactive hypoglycemia may be caused by ………………………… & ……………………….
Mansoura Faculty of medicine
Medical Biochemistry Department
Quiz (2)
Second year
(Carbohydrate Metabolism)
Student name:……………………………………
score :10
section: …………………………….
Student number:…………………..Time : 10 min
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I)
Choose the best answer:
1- Regarding gluconeogenesis:
a) It has fewer enzymes than glycolysis
b) Its activity increases with energy charge and decreases as AMP increases.
c) It occurs completely in the cytoplasm
d) All of the abovee) None of the above
2- The citric acid cycle:
a) Enzymes are located in the intermitochomdrial membrane space
b) Generate GTP by substrate-level phosphorylation
c) Includes enzymes that catalyze anaplerotic reactions
d) Involves a priming step that requires ATP
3- In the breakdown of muscle glycogen, the predominant product is:
a) Glucose b) Glucose-1-phosphate c)UDP-glucose d) Maltose
4- Cataract may result from osmotic imbalance in the lens of the eye caused by
theaccumulation of:
a) Galactoseb) Glucose c) Sugar alcohols
d)Amino sugars
5- Which one of the following statements is incorrect about glucose-6-P?
a) It is oxidized by Glucose-6-P dehydrogenase
b) It has an increased rate of oxidation in the disease favism
c) It is hydrolyzed to glucose and phosphate by the cytoplasmic Glucose-6phosphatase enzyme
d) It is synthesized from ATP and glucose by hexokinase enzyme
II)
Complete the following sentences:1- All glucose transporters proteins are insulin independent except …………………..
2- Phosphorylase enzyme product is …………….……. because it act on …………………
………………………………………………………………………………………………………………………..
3- Glucagon can inhibit pyruvate kinase by …………………………….. & ………………….…
4- Arsenite can inhibit………………………………… & …………………….……………
enzymesbecause
it
……………………………………………………………………………………………………….
5- Hereditary fructose intolerance causes ………………………………….. hypoglycemia
Mansoura Faculty of medicine
Medical Biochemistry Department
Quiz (2)
Second year
(Carbohydrate Metabolism)
Student name:……………………………………
score :10
section: …………………………….
Student number:…………………..Time : 10 min
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I)
Choose the best answer:
1- Which vitamin of the following is not a part of pyruvate dehydrogenase:
a) Pantothenic acid
b) Thiaminec) Niacin d)Vit. B12
2- Continuous operation of the pentose phosphate pathway in red blood cells:
a) Produces H2O2 for the oxidation of glutathione
b) Produces one NADH for every glucose-6-phosphate decarboxylated
c) Requires NADP+ regeneration from NADPH
d) Require utilization of pyruvate by pyruvate dehydrogenase
e) Requires utilization of ribose 5-phosphate for nucleotide synthesis
3- In along term fast (more than 30 hours) most of the blood glucose is derived
from:
a) Acetyl-CoA
b) Amino acids c) Muscle glycogen d)Liver glycogen
4- Which of the following enzymes is affected directly by citrate?
a) Fructose-2,6-biphosphatase
b)Isocitrate dehydrogenase
c) Phosphofructokinase-1
d) pyruvate carboxylase
5) Gluconeogenesis is the conversion of the following compounds to glucose
EXCEPT:
a) Lactate
b) Propionate c) Kreb`s cycle intermediates d)Acetoacetate
II)
Complete the following sentences:1- SGLUT 1 is present in …………………………………… and …………………………………………
2- Phosphorylase enzyme is considered as …..........................................……. while
debranching enzyme is ………..……………………………… as regard its action.
3- Insulin can activate pyruvate kinase by ………………………………………………………
and …………………………………………………………………………………………………………………
4- Succinate dehydrogenase enzyme can be inhibitedby ……………………..… which
act as ……………………………………………………………………………………………………….…
Mansoura Faculty of medicine
Medical Biochemistry Department
Quiz (2)
Second year
(Carbohydrate Metabolism)
Student name:……………………………………
score :10
section: …………………………….
Student number:…………………..Time : 10 min
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5- Key regulatory enzyme of pentose shunt is …………………………………. And
induced by …………………………………………..
I) Choose the best answer:
1- Formation of 6-phosphoglucosamine from F-6-P is an example of:
a) Transamination b) Transdeamination
c)Transamidationd)Transamidination
2- The enzyme that converts dihydroxyacetone phosphate to glycerol 3-phosphate
iscalled:
a) Dihydroxyacetone phosphate hydrolase
b) FAD-linked glycerol 3-phosphate dehydrogenase
c) Glyceraldhyde 3-phosphate dehydrogenase
d) NAD-linked glycerol-3-phosphate dehydrogenase
3- Which of the following hormonal effects is significant in muscle but not in liver?
a) Epinephrine stimulated glycogenolysis
b) Insulin stimulated glycogen synthesis
c) Insulin stimulated glucose transport
d) Glucagon stimulated gluconeogenesis
e) Glucagon stimulated glycogenolysis
4- The only sugar which can bypass phosphofructokinase reaction is:
a) Mannose
b) Dextrose c) Pentose
d) Lactose e)Levulose
5- Glycolysis in RBCs includes all of the following EXCEPT:
a) It ends by lactic acid and oxidized NAD
b) The energy production is 6 moles of ATP
c) It gives 2,3 diphosphoglycerate that stimulate HBO2 dissociation at
peripheral tissues
d) In vitro it is inhibited by fluoride
II)
Complete the following sentences:1- Facilitative diffusion of glucose in liver occurs by ………………………….………………..
2- Glycogen synthese form ……………………………….……. during glycogen formation.
3- pyruvate kinase isallosterically activated by ……………………………………………. and
inhibited by ………………………….………………………………………………………………….
4- Flouroacetate can react with …………………… & inhibit ………………………….……..…
Mansoura Faculty of medicine
Medical Biochemistry Department
Quiz (2)
Second year
(Carbohydrate Metabolism)
Student name:……………………………………
score :10
section: …………………………….
Student number:…………………..Time : 10 min
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5- Lactic acidosis may be caused by deficiency of …………………………………………..
and ……………………………………………………….. enzymes.