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Biochemistry MCQs PMU 2nd Year

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Biochemistry MCQs 3rd Coloquim PMU 2nd Year

Question 1 of 42

1

Which are the regulatory enzymes in glycolysis?

Select one or more of the following:

  • Hexokinase

  • Glucose-6-phosphate Isomerase

  • Phosphofructokinase

  • Phosphoglycerate Mutase

  • Pyruvate Kinase

Explanation

Question 2 of 42

1

Which enzymes participate in pentose phosphate pathway?

Select one or more of the following:

  • Glucose-6-phosphate Dehydrogenase

  • Transaldolase

  • Transketolase

  • Phosphofructokinase

  • Pyruvate Kinase

Explanation

Question 3 of 42

1

Gluconeogenesis occurs in:

Select one or more of the following:

  • Cytosol

  • Endoplasmic Reticulum

  • Mitochondria

  • Both Cytosol and Endoplasmic Reticulum

  • Cytosol, Mitochondria and Endoplasmic Reticulum

Explanation

Question 4 of 42

1

Which of the molecule is "linkage" between the citric acid cycle and gluconeogenesis?

Select one or more of the following:

  • Citrate

  • Isocitrate

  • Malate

  • Oxaloacetate

  • Succinyl-CoA

Explanation

Question 5 of 42

1

Which of the vitamins is involved in gluconeogenesis as coenzyme?

Select one or more of the following:

  • Vitamin C

  • Vitamin H (biotin)

  • Vitamin B1 (thiamine pyrophosphate)

  • Vitamin PP (NAD, NADH)

  • Vitamin B2 (FAD, FMN)

Explanation

Question 6 of 42

1

Show the energy source responsible for gluconeogenesis energy supply:

Select one or more of the following:

  • GTP and UTP

  • ATP and GTP

  • ATP and UTP

  • Acetyl-CoA

  • Glucose-6-Phosphate

Explanation

Question 7 of 42

1

Which of the following citric acid cycle intermediates, derived from α-amino acids, give carbon atoms for gluconeogenesis?

Select one or more of the following:

  • citrate

  • pyruvate

  • succinyl-CoA

  • α-ketoglutarate

  • oxaloacetate

Explanation

Question 8 of 42

1

Which of the following is true?

Select one or more of the following:

  • 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

Explanation

Question 9 of 42

1

Which of the following enzymes are regulatory in gluconeogenesis:

Select one or more of the following:

  • Pyruvate carboxylase

  • Glucose-6-phosphatase

  • Phosphofructokinase

  • Pyruvate kinase

  • ΡΕΡ carboxykinase

Explanation

Question 10 of 42

1

Which of the following hormones stimulate gluconeogenesis:

Select one or more of the following:

  • insulin

  • glucagon

  • cortisol

  • adrenaline

Explanation

Question 11 of 42

1

Gluconeogenesis:

Select one or more of the following:

  • 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

Explanation

Question 12 of 42

1

Which are the true statements about regulation of glycolysis?

Select one or more of the following:

  • 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

Explanation

Question 13 of 42

1

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?

Select one of the following:

  • 2

  • 3

  • 4

  • 6

  • 8

Explanation

Question 14 of 42

1

Which of the following statements about insulin and glucagon are true?

Select one or more of the following:

  • 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

Explanation

Question 15 of 42

1

Glycogen:

Select one or more of the following:

  • 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

Explanation

Question 16 of 42

1

Which of the following is TRUE?

Select one or more of the following:

  • 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

Explanation

Question 17 of 42

1

By which of the following fatty acids derive carbon atoms for the gluconeogenesis?

Select one or more of the following:

  • citrate

  • propionate

  • pyruvate

  • lactate

  • acetyl-COA

Explanation

Question 18 of 42

1

Which are the common metabolites for glycolysis and pentose phosphate pathway?

Select one or more of the following:

  • Erythrose-4-phosphate

  • Fructose-1,6-bisphosphate

  • Glucose-6-phosphate

  • Glyceraldehyde-3-phosphate

  • Dihydroxyacetone phosphate

  • Fructose-6-phosphate

  • Pyruvate

Explanation

Question 19 of 42

1

Which of the following statements about glycogen degradation in liver are true?

Select one or more of the following:

  • 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

Explanation

Question 20 of 42

1

Which of the following statements about fructose are true?

Select one or more of the following:

  • 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

Explanation

Question 21 of 42

1

In which of the following pathways does UDP participate?

Select one or more of the following:

  • Glycolysis

  • Gluconeogenesis

  • Synthesis of glycogen

  • Degradation of glycogen

  • Galactose metabolism

  • Pentose phosphate pathway

Explanation

Question 22 of 42

1

Glucagon secretion increases:

Select one or more of the following:

  • at high insulin levels

  • at low insulin levels

  • at high blood glucose content

  • at low blood glucose content

  • in fasting

Explanation

Question 23 of 42

1

Which of the following is TRUE?

Select one or more of the following:

  • 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

Explanation

Question 24 of 42

1

Which of the following is TRUE

Select one or more of the following:

  • glycogen phosphorylase is active phosphorylated

  • hormones like glucagon and adrenaline increase glycogenolysis

  • a rise in cAMP concentration activates glycogen synthase

  • insulin increases glycogenolysis

Explanation

Question 25 of 42

1

Which are the major precursors for glucose production via gluconeogenesis?

Select one or more of the following:

  • lactate

  • glucogenic amino acids

  • glycerol

  • fructose

  • acetyl-CoA

Explanation

Question 26 of 42

1

Which of the following about pentose phosphate pathway (PPP) is TRUE?

Select one or more of the following:

  • 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

Explanation

Question 27 of 42

1

Which of the following is TRUE?

Select one or more of the following:

  • 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

Explanation

Question 28 of 42

1

Which of the following enzymes participate in glycolysis?

Select one or more of the following:

  • Hexokinase

  • Glucose-6-phosphatase

  • Phosphofructokinase

  • Pyruvate kinase

  • PEP carboxykinase

Explanation

Question 29 of 42

1

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)?

Select one or more of the following:

  • 32

  • 38

  • 24

  • 12

  • 2

Explanation

Question 30 of 42

1

Insulin stimulates:

Select one or more of the following:

  • glycolysis

  • lipolysis

  • gluconeogenesis

  • glycogen degradation

  • glycogen synthesis

Explanation

Question 31 of 42

1

Which of the following statements about pentose phosphate pathway are true?

Select one or more of the following:

  • 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

Explanation

Question 32 of 42

1

Which are the regulatory enzymes in gluconeogenesis?

Select one or more of the following:

  • Glucokinase

  • Phosphoglucomutase

  • Phosphoenolpvruvate carboxykinase

  • Pyruvate kinase

  • Pyruvate carboxylase

  • Glucose-6-phosphatase

  • Fructose-1,6-bisphosphatase

Explanation

Question 33 of 42

1

Galactose:

Select one or more of the following:

  • 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

Explanation

Question 34 of 42

1

Which of the following statements about carbohydrate metabolism in red blood cells are true?

Select one or more of the following:

  • 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

Explanation

Question 35 of 42

1

Which of the following is TRUE?

Select one or more of the following:

  • 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

Explanation

Question 36 of 42

1

Glycogen:

Select one or more of the following:

  • 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

Explanation

Question 37 of 42

1

Which of the following statements about insulin and glucagon are true?

Select one or more of the following:

  • 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

Explanation

Question 38 of 42

1

Which of the following statements about regulation of carbohydrate metabolism are true?

Select one or more of the following:

  • 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

Explanation

Question 39 of 42

1

Which of the following statements are true?

Select one or more of the following:

  • 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

Explanation

Question 40 of 42

1

Which of the following statements about regulation of glycolysis are TRUE?

Select one or more of the following:

  • 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

Explanation

Question 41 of 42

1

Which of the following is TRUE?

Select one or more of the following:

  • 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

Explanation

Question 42 of 42

1

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?

Select one or more of the following:

  • 2

  • 3

  • 4

  • 5

  • 6

Explanation

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