Monday, October 22, 2012

Carbohydrate metabolism

Q.1-Which of the following enzymes is Thiamine dependent and essential for glucose oxidation in the brain?

a) Pyruvate dehydrogenase complex                

b) Acetyl co A carboxylase

c) Transaldolase                          

d) Succinyl-co A Thiokinase                                         (     a    )

Q.2- The reaction catalyzed by phosphofructo kinase is -

 a) Inhibited by Fructose 2,6 bisphosphate                  

b) Activated by high concentration of ATP

c) A regulatory step of glycolysis  

d) All of the above                                                      (      c   )

Q.3- Pyruvate carboxylase requires ————— as a coenzyme.

a) FMN                              

b) Biotin

c) NAD+

d) TPP                                                                        (    b     )

Q.4- In erythrocytes the most abundantly found Phospho ester is-

 a) Glucose-6 phosphate                

b) Fructose 1, 6 bisphosphate

c) Fructose-6- phosphate

d) 2, 3 bisphosphoglycerate                                        (    d     )

Q.5- Formation of Galactose-1-P from Galactose is catalyzed by-

a) Hexokinase                            

b) Aldolase    

c) Galactokinase                          

d) Galactose-1-P Uridyl transferase                               (     c    )

Q.6- All the following enzymes except one require NADP+ as a coenzyme-

 a) Glucose- 6-phosphate dehydrogenase          

b) Cytosolic Isocitrate dehydrogenase

c) Malic enzyme      

d) Glucose-6-phophatase                                               (     d    )

Q.7- Which of the following product of Triglyceride breakdown and subsequent beta oxidation would undergo gluconeogenesis-

a) Propionyl Co A                        

b) Acetyl CoA

c) Aceto acetate                          

d) Beta hydroxy butyrate                                                 (     a    )

Q.8 – Which of the following reactions generates ATP?

 a) Glucose to Glucose -6-phosphate        

b) Pyruvate to Lactate

c) Phosphoenol pyruvate to Pyruvate      

d) Glucose- 6 phosphate to fructose-6 phosphate             (   c      )

Q.9- Glucose enters muscle cells mostly by:

 a) Simple diffusion

b) Facilitated diffusion using a specific glucose transporter

c) Co-transport with sodium

d) Co-transport with amino acids                                      (     b    )

Q.10- Which one of the following compounds is common to both the oxidative phase and the non- oxidative phase of the pentose phosphate pathway?

 a) Xylulose-5- phosphate                        

b) Glucose-6-phosphate

c) Ribulose-5-phosphate                        

d) Glyceraldehyde-3- phosphate                                        (      a     )

Q.11- Mc Ardle’s syndrome causes muscle cramps and muscle fatigue with increased muscle glycogen. Which of the following enzyme is deficient?

 a) Hepatic hexokinase                            

b) Muscle Phosphorylase

c) Muscle Debranching enzyme              

d) Muscle Hexokinase                                                         (    b     )

Q.12- During starvation, the major source of blood glucose is-

 a) Hepatic Glycogenolysis                      

b) Gluconeogenesis

c)  Muscle Glycogenolysis                      

d) Dietary glucose from intestine                                          (    b     )

Q.13- Hexokinase has a considerably lower km for-

 a) Glucose                                  

b) Fructose

c) Galactose

d) Mannose                                                                          (     a    )

Q.14- In the fasting state there is considerable release of———–from the muscles.

 a) Glycine                                    

b) Alanine      

c) Valine

d) Glutamic acid                                                                  (     b    )

Q.15- A galactosemic child will manifest all except-

 a) Hepatomegaly                          

b) Splenomegaly

c) Cataract

d) Mental retardation                                                            (     b    )

Q16- – Which one of the following reactions is unique to gluconeogenesis-?

a) Lactate<———–>Pyruvate

b) Oxaloacetate—->Phosphoenol pyruvate

c) Glucose-6-phosphate—– >Glucose

d) Phosphoenol pyruvate–>Pyruvate                                    (      b   )

Q.17- The main stores of glycogen are found in—

 a) Adipose tissues    

b) Skeletal muscles            

c) Brain                            

d) Erythrocytes                                                                    (     b    )

Q.18- Succinyl co A is cleaved by-

 a) Succinate dehydrogenase          

b) Succinate Thiokinase

c) Succinate lyase                        

d) Succinate Thioesterase                                                     (    b     )

Q.19- Arsenate binds to-

 a)  Free amino end of enzyme                

b) SH linkages

c) Free carboxyl end

d) Any of the above                                                               (     b    )

Q.20- All are intermediates of glycolysis except-

a) Glucose-6 phosphate                

b) Fructose 1, 6 bisphosphate

c) Fructose-6- phosphate              

d) Glycerol – 3- phosphate                                                    (     d    )

Q.21- The key regulatory enzyme of HMP pathway is-

 a) Glucose- 6-phosphate dehydrogenase

b) Transaldolase

c) Transketolase                          

d) Glucose-6-phophatase                                                       (     a    )

Q.22- The net production of ATP in glycolysis during anaerobic condition is:

 a) 2 from glucose and 3 from glycogen

b) 2 from glucose and 4 from glycogen

c) 3 from glucose and 4 from glycogen

d) 3 from glucose and 2 from glycogen                                   (   a      )

Q.23- Which of the followings does not generate free glucose during the enzymatic breakdown of glycogen in skeletal muscles?

 a) Phosphorylase                        

b) α-1-6-amyloglucosidase  

c) Debranching enzyme      

d) glucose-6-phosphatase                                                          (     a    )

Q.24- Which of the followings promotes glucose and amino acid uptake by muscle?

a) Adrenaline                              

b) Insulin

c) Glucagon                                

d) Cortisol                                                                                   (     b    )

Q.25- In a tissue that metabolizes glucose via the pentose phosphate pathway, C-1 of glucose would be expected to end up principally in:

a) Carbon dioxide                                  

b) Glycogen

c) Phosphoglycerate                              

d) Pyruvate                                                                                   (   a      )

------------------------------------------ Best Wishes: Dr.Ehab Aboueladab, Tel:01007834123, ------------------------------------------
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