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Biochemistry MCQs 3rd Coloquim PMU 2nd Year

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Biochemistry MCQs PMU 2nd Year
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Question 1

Question
Which are the regulatory enzymes in glycolysis?
Answer
  • Hexokinase
  • Glucose-6-phosphate Isomerase
  • Phosphofructokinase
  • Phosphoglycerate Mutase
  • Pyruvate Kinase

Question 2

Question
Which enzymes participate in pentose phosphate pathway?
Answer
  • Glucose-6-phosphate Dehydrogenase
  • Transaldolase
  • Transketolase
  • Phosphofructokinase
  • Pyruvate Kinase

Question 3

Question
Gluconeogenesis occurs in:
Answer
  • Cytosol
  • Endoplasmic Reticulum
  • Mitochondria
  • Both Cytosol and Endoplasmic Reticulum
  • Cytosol, Mitochondria and Endoplasmic Reticulum

Question 4

Question
Which of the molecule is "linkage" between the citric acid cycle and gluconeogenesis?
Answer
  • Citrate
  • Isocitrate
  • Malate
  • Oxaloacetate
  • Succinyl-CoA

Question 5

Question
Which of the vitamins is involved in gluconeogenesis as coenzyme?
Answer
  • Vitamin C
  • Vitamin H (biotin)
  • Vitamin B1 (thiamine pyrophosphate)
  • Vitamin PP (NAD, NADH)
  • Vitamin B2 (FAD, FMN)

Question 6

Question
Show the energy source responsible for gluconeogenesis energy supply:
Answer
  • GTP and UTP
  • ATP and GTP
  • ATP and UTP
  • Acetyl-CoA
  • Glucose-6-Phosphate

Question 7

Question
Which of the following citric acid cycle intermediates, derived from α-amino acids, give carbon atoms for gluconeogenesis?
Answer
  • citrate
  • pyruvate
  • succinyl-CoA
  • α-ketoglutarate
  • oxaloacetate

Question 8

Question
Which of the following is true?
Answer
  • the enzyme activity of fructose 1,6-bisphosphatase is increased by ΑΤΡ
  • the enzyme activity of fructose 1,6-bisphosphatase is increased by ADP
  • the enzyme activity of fructose l,6-bisphosphatase is decreased by ATP
  • the enzyme activity of fructose 1,6-bisphosphatase is decreased by ADP
  • fructose 2,6-bisphosphate is the most potent activator for gluconeogenesis and Inhibitor for glycolysis

Question 9

Question
Which of the following enzymes are regulatory in gluconeogenesis:
Answer
  • Pyruvate carboxylase
  • Glucose-6-phosphatase
  • Phosphofructokinase
  • Pyruvate kinase
  • ΡΕΡ carboxykinase

Question 10

Question
Which of the following hormones stimulate gluconeogenesis:
Answer
  • insulin
  • glucagon
  • cortisol
  • adrenaline

Question 11

Question
Gluconeogenesis:
Answer
  • Is stimulated by insulin
  • Is stimulated by glucagon
  • Is major pathway in liver and kidneys
  • Can also be performed in muscles
  • Causes a decrease in blood glucose level

Question 12

Question
Which are the true statements about regulation of glycolysis?
Answer
  • Hexokinase is not a regulatory enzyme
  • Glucokinase is not inhibited allosterically by glucose-6-phosphate
  • Phosphofructokinase 1 is the most important regulatory enzyme
  • Fructose-2,6-bisphosphate activates glycolysis
  • Insulin causes a decrease in the concentration of fructose-2,6-bisphosphate

Question 13

Question
How many molecules of ATP are created from NADH+H+ generated from 1 molecule glucose in glycolysis, if transported into the mitochondria by malate shuttle? Explain why?
Answer
  • 2
  • 3
  • 4
  • 6
  • 8

Question 14

Question
Which of the following statements about insulin and glucagon are true?
Answer
  • Insulin is secreted in periods of starvation
  • Insulin is secreted by α-cells of the pancreas to decrease blood glucose level after meal
  • Glucagon is secreted in case of low blood glucose levels
  • Insulin stimulates pentose phosphate pathway
  • Glucagon is the main hormone that stimulates gluconeogenesis

Question 15

Question
Glycogen:
Answer
  • Is a linear polymer composed only of glucose residues
  • Is synthesized in response to insulin stimulation over the main regulatory enzyme- the branching enzyme
  • Is present at any cell but most prominently in liver and muscle cells
  • Is synthesized in periods of starvation
  • Its regulatory enzymes both in synthesis and degradation can be controlled allosterically as well as through reversible covalent modification

Question 16

Question
Which of the following is TRUE?
Answer
  • the main regulative enzyme in glycolysis is phosphofructokinase 1
  • the main regulative enzyme in glycolysis is glyceraldehyde-1-phosphate dehydrogenase
  • hexokinase involved in glycolysis is regulated by product of the reaction- glucose-6-phosphate
  • pyruvate kinase involved in glycolysis is regulated by covalent modification (reversible phosphorylation/ dephosphorylation) only in the liver
  • pyruvate kinase involved in glycolysis is regulated by covalent modification (reversible phosphorylation/ dephosphorylation) only in the tissues

Question 17

Question
By which of the following fatty acids derive carbon atoms for the gluconeogenesis?
Answer
  • citrate
  • propionate
  • pyruvate
  • lactate
  • acetyl-COA

Question 18

Question
Which are the common metabolites for glycolysis and pentose phosphate pathway?
Answer
  • Erythrose-4-phosphate
  • Fructose-1,6-bisphosphate
  • Glucose-6-phosphate
  • Glyceraldehyde-3-phosphate
  • Dihydroxyacetone phosphate
  • Fructose-6-phosphate
  • Pyruvate

Question 19

Question
Which of the following statements about glycogen degradation in liver are true?
Answer
  • The regulatory enzyme is glycogen phophorylase
  • The regulatory enzyme is debranching enzyme
  • The regulatory enzyme is activated by ATP and glucose-6-phosphate
  • It is a source of energy for the liver itself
  • It is most fast activated mechanism for maintenance of blood glucose level in periods of fasting
  • The degradation stops till glucose-6-phosphate

Question 20

Question
Which of the following statements about fructose are true?
Answer
  • It is absorbed mainly through GLUT5
  • Can be metabolized in muscles by fructokinase and enter glycolysis in one step
  • Can be metabolized in liver, skeletal muscles, spermatozoa and other extrahepatic tissues but by different enzymes
  • A deficiency in aldolase B causes fructose intolerance
  • In liver fructose enters glycolysis at the level of trioses-glyceraldehyde-3-phosphate and dihydroxyacetone phosphate

Question 21

Question
In which of the following pathways does UDP participate?
Answer
  • Glycolysis
  • Gluconeogenesis
  • Synthesis of glycogen
  • Degradation of glycogen
  • Galactose metabolism
  • Pentose phosphate pathway

Question 22

Question
Glucagon secretion increases:
Answer
  • at high insulin levels
  • at low insulin levels
  • at high blood glucose content
  • at low blood glucose content
  • in fasting

Question 23

Question
Which of the following is TRUE?
Answer
  • liver glycogen stores and exports glucose to maintain blood glucose
  • liver and muscles lack glucose-6-phospatase
  • the synthesis of glycogen is initiated by the formation of glycogen primer
  • the cleavage of glycogen by glycogen phosphorylase yields UDPGlc

Question 24

Question
Which of the following is TRUE
Answer
  • glycogen phosphorylase is active phosphorylated
  • hormones like glucagon and adrenaline increase glycogenolysis
  • a rise in cAMP concentration activates glycogen synthase
  • insulin increases glycogenolysis

Question 25

Question
Which are the major precursors for glucose production via gluconeogenesis?
Answer
  • lactate
  • glucogenic amino acids
  • glycerol
  • fructose
  • acetyl-CoA

Question 26

Question
Which of the following about pentose phosphate pathway (PPP) is TRUE?
Answer
  • it generates NADPH for reductive biosynthesis
  • it generates ribose phosphate for nucleotide and nucleic acids formation
  • the enzymes of PPP are mitochondrial
  • PPP protects the erythrocytes against hemolysis

Question 27

Question
Which of the following is TRUE?
Answer
  • citrate and ATP are allosteric inhibitors of phosphofructokinase-1
  • fructose-2,6-bisphosphate is an allosteric activator of phosphofructokinase-1
  • phosphofructokinase-1 activity is increased by insulin
  • phosphofructokinase-1 activity is increased by glucagon

Question 28

Question
Which of the following enzymes participate in glycolysis?
Answer
  • Hexokinase
  • Glucose-6-phosphatase
  • Phosphofructokinase
  • Pyruvate kinase
  • PEP carboxykinase

Question 29

Question
What is the ATP production in complete glucose oxidation to CO2 and water (mol ATP per mol of glucose; NADH is transported into mitochondria by the malate shuttle)?
Answer
  • 32
  • 38
  • 24
  • 12
  • 2

Question 30

Question
Insulin stimulates:
Answer
  • glycolysis
  • lipolysis
  • gluconeogenesis
  • glycogen degradation
  • glycogen synthesis

Question 31

Question
Which of the following statements about pentose phosphate pathway are true?
Answer
  • It is the major donor of NADH+H+
  • It is the major donor of NADPH+H+
  • It is located in the mitochondria
  • Its major goal is generation of energy
  • it produces reducing agents for various synthesis but also ribose for nucleic acids formation

Question 32

Question
Which are the regulatory enzymes in gluconeogenesis?
Answer
  • Glucokinase
  • Phosphoglucomutase
  • Phosphoenolpvruvate carboxykinase
  • Pyruvate kinase
  • Pyruvate carboxylase
  • Glucose-6-phosphatase
  • Fructose-1,6-bisphosphatase

Question 33

Question
Galactose:
Answer
  • ls metabolized both in liver and extrahepatic tissues
  • Is metabolized only in liver
  • Its metabolism requires UDP
  • Can be used for maintenance of blood glucose level
  • Galactosemia type I (classical) is caused by deficiency in galactokinase

Question 34

Question
Which of the following statements about carbohydrate metabolism in red blood cells are true?
Answer
  • Glycolysis can be performed either in aerobic or anaerobic conditions
  • The terminal product of glycolysis is always lactate
  • RBC contain smaller amounts of 2,3 bisphosphoglycerate compared the rest of the cells
  • Pentose phosphate pathway is of vital importance for the RBC
  • RBC participate in Cori Cycle

Question 35

Question
Which of the following is TRUE?
Answer
  • all of the enzymes of glycolysis are in the cytosol
  • glucokinase is an isoenzyme of hexokinase in liver and pancreatic β-cells
  • phosphofructokinase-1 is a major regulatory enzyme of glycolysis
  • glycolyis is a pathway that can function only aerobically

Question 36

Question
Glycogen:
Answer
  • ls a branched polymer composed only of glucose residues
  • The main regulatory enzyme of its synthesis - glycogen synthase, is activated by epinephrine
  • ls present most prominently in liver and muscle cells but has different function in them
  • The regulatory enzymes both in synthesis and degradation can be controlled allosterically as well as through reversible covalent modification
  • α-(1->6) glycosidic bond cleavage is executed by glycogen phosphorylase

Question 37

Question
Which of the following statements about insulin and glucagon are true?
Answer
  • Insulin is secreted in response to hyperglycemia
  • Insulin is secreted in response to hypoglycemia
  • Glucagon is activator of gluconeogenesis and glycogen degradation
  • Insulin inhibits pentose phosphate pathway
  • Insulin activates phosphofructokinase 1 and thus glycolysis

Question 38

Question
Which of the following statements about regulation of carbohydrate metabolism are true?
Answer
  • Fructose-2,6-bisphosphate is aIIosteric activator of glycoiysis and inhibitor of giuconeogenesis
  • Fructose-2,6-bisphosphate is allosteric inhibitor of glycoiysis and activator of giuconeogenesis
  • ATP and citrate are inhibitors of glycolysis
  • AMP is an activator of glycoiysis

Question 39

Question
Which of the following statements are true?
Answer
  • Deficiency in glucose-6-phosphate dehydrogenase may cause haemolytic anaemia
  • Fructose is metabolized only in liver
  • Fructosuria is caused by deficiency in fructokinase
  • Glucose is transported in liver and pancreas through GLUT 3

Question 40

Question
Which of the following statements about regulation of glycolysis are TRUE?
Answer
  • Hexokinase is not a regulatory enzyme
  • Glucokinase is not inhibited allosterically by glucose-6-phosphate
  • Phosphofructokinase 1 is the most important regulatory enzyme
  • Fructose-2,6-bisphosphate activates glycolysis
  • Insulin causes a decrease in the concentration of fructose-2,6-bisphosphate

Question 41

Question
Which of the following is TRUE?
Answer
  • glycogen phosphorylase is active dephosphorylated
  • hormones like glucagon and adrenaline increase glycogen synthesis
  • a rise in cAMP concentration activates glycogen phosphorylase
  • insulin increases glycogen synthesis

Question 42

Question
How many molecules of ATP are created from NADH+H+ generated from 1 molecule glucose in glycolysis, if transported into the mitochondria by glycerol-3-phosphate shuttle? Explain why?
Answer
  • 2
  • 3
  • 4
  • 5
  • 6
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