glycolysis

1) Which of these enzyme reactions is not irreversible in glycolysis?

a) Hexokinase

b) Glucokinase

c) 3-phosphoglycerate kinase

d) Phosphofructokinase-1

e) Pyruvate kinase

2) Which out of the following statements is not true about aerobic glycolysis ?

a) The rate limiting enzyme is phosphofructokinase-1 which converts fructose-6- phosphate to fructose-1,6-bisphosphate

b) The pathway is inhibited allosterically by fructose-2,6-bisphosphate and AMP

c) The pathway takes place in mitochondria of every cell

d) The pathway produces Pyruvate and NADH

e) The pathway begins with glucokinase or hexokinase

3) The first step in the glycolytic pathway in Liver -

a) Is catalyzed by glucokinase

b) Uses ATP and glucose as substrates

c) Produces glucose-6-phosphate and ADP

d) Is an irreversible step

e) All of the above.

4) Phosphoglycerate kinase functions in carbohydrate metabolism to produce ATP via:

a) Oxidative phosphorylation.

b) Substrate level phosphorylation.

c) Oxidative decarboxylation.

d) Phosphorolysis

e) Oxidative deamination

5). The phosphofructokinase-2 enzyme that transfers a phosphate group to fructose-6-phosphate in glycolysis-

a) Is active in the phosphorylated form

b) Catalyzes a reversible reaction

c) Produces fructose-2,6-bisphosphate as a product

d) Is the rate limiting enzyme for glycolysis

e) Produces ATP as a product.

6). The enzyme that produces NADH from a triose phosphate in the glycolytic pathway-

a) Uses NAD+ and dihydroxyacetone phosphate as substrates

b)Produces 3-phosphoglycerate and NADH

c) Is reversible

d) Is called 3-phosphoglycerate kinase

e) Uses FADH2 and glyceraldehyde-3-phosphate as substrates

7). The enzyme that catalyzes first substrate level phosphorylation in glycolysis-

a) Produces 3-phosphoglycerate as a product

b) Produces ADP from AMP

c) Is called glyceraldehyde-3-phosphate dehydrogenase

d) Is called phosphofructokinase

e) Is the rate limiting enzyme of glycolysis.

8). The enzyme that catalyzes the second substrate level phosphorylation of glycolysis-

a) Is called phosphoglyceromutase

b) Produces lactate as a product

c) Uses phosphoenolpyruvate as a substrate

d) Catalyzes a reversible reaction

e) Is stimulated by Glucagon.

9). Which of the following statements about the Lactate dehydrogenase (LDH) reaction is false

a) The enzyme converts pyruvate to lactate

b)The enzyme converts NADH to NAD+

c) The reaction is reversible

d) It is the last enzyme reaction in glycolysis

e) The enzyme is highly active under aerobic conditions

10). The two major factors determining whether a cell oxidizes glucose by aerobic glycolysis or by anaerobic glycolysis are-

a) FADH2 and the number of mitochondria

b) NADH and the ATP/ADP ratio

c) Ca++ and AMP

d) Oxygen pressure and the number of mitochondria

e) Presence of low Glucose and high AMP

11). When glucose is converted to lactate by anaerobic glycolysis, the equivalent of ________ ATPs are derived.  When glucose is completely oxidized to CO2 by glycolysis, Pyruvate dehydrogenase, and the TCA cycle, the equivalent of _______ ATPs are derived.

a) 7;  20

b) 2;  38

c) 7;  32

d)2;  12

e) 7;  25

12).Choose the incorrect statement about the condition ‘When one molecule of glucose is oxidized to 2 molecules of lactate during anaerobic glycolysis’-

a) One molecule of ATP is used by the phosphofructokinase-1 reaction

b)One molecule of ATP is used by either the glucokinase or hexokinase reaction

c) Two molecules of ATP are produced by the Glyceraldehyde -3-P dehydrogenase reaction

d) Two molecules of ATP are produced by the pyruvate kinase reaction

e) No ATP is produced at the level of lactate dehydrogenase reaction.

13). All of the following help to explain some cases of Lactic Acidosis except-

a) High altitude

b) Heart failure

c) Not enough oxygen to satisfy the needs of oxidative phosphorylation

d) Congenital deficiency of liver lactate dehydrogenase

e) Inhibition of the electron transport chain

14) . All of the following are part of the Cori Cycle except-

a) Lactate is the result of anaerobic glycolysis in a number of tissues

b) Lactate is transported to the liver

c) Lactate is converted to glucose in the liver

d) ATP is produced by the conversion of lactate to glucose

e) Glucose is transported from liver to other tissues

15). The ATP/AMP ratio has a major effect upon the rate of ATP production by glycolysis.  ATP and AMP bind to allosteric sites on-

a) Hexokinase

b) Glucokinase

c) Phosphofructokinase-1

d) Phosphofructokinase-2

e) 3-phosphoglycerate kinase

16). Which of the following statements about pyruvate kinase is false -

a) Can convert Phosphoenol pyruvate to pyruvate

b) Is regulated by feed forward regulation

c) Is active in the dephosphorylated form

d) Is also involved in gluconeogenesis

e) Deficiency causes haemolytic anemia.

17). Pasteur effect is due to inhibition of glycolysis by high concentration of -

a) Creatine phosphate

b) ATP

c) ADP

d) AMP

e) Pi

18). In the liver, glucagon causes a decrease in the glycolytic pathway by all of the following mechanisms  except-

a) Increased binding of GTP to G-protein

b) Activation of the cAMP cascade

c) Increased phosphorylation of enzymes by protein kinase A

d) Activation of fructose-2,6-bisphosphatase and inhibition of phosphofructokinase-2

e) Increased binding of fructose-2,6-bisphosphate to phosphofructokinase-1

19). An increased concentration of insulin after meals causes an increase in the rate of  glycolytic pathway by all of the following mechanisms except-

a) Increase uptake of glucose in adipose tissue and muscle

b) Inactivation of the cAMP cascade

c) Increased  dephosphorylation of enzymes activated by protein kinase A

d) Activation of fructose-2,6-bisphosphatase and inhibition of phosphofructokinase-2

e) Induction of Glucokinase and PFK-1

20).During fasting state, the insulin to glucagon ratio drops and all of the following occur except-

a) Protein kinase A will phosphorylate pyruvate kinase

b) The pyruvate kinase step will be activated

c) Protein kinase A will phosphorylate phosphofructokinase-2/fructose-2,6-bisphosphatase

d) The concentration of fructose-2,6-bisphosphate will decrease

e)The liver will not be able to synthesize pyruvate from phosphoenolpyruvate.

21) A high concentration of Glucose-6-P  is inhibitory to which of the following enzymes ?

a) Hexokinase

b) Glucokinase

c) PFK-1

d) PFK-2

e) All of the above,





Answers-       1)-c,               2)- b,              c)-e,               4)-b,               5)-c,               6)-b,                        

                     

                       7)-a,               8)- c,              9)-e,               10)-b,                        11)-b,                        12)-c

                     

                        13)-d              14)-d              15)-c              16)-d              17)-b              18)-e

                     

                        19)-d              20)-b              21)-a



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