biochemistry test

1) Which one one of the following following sets sets of glycolytic glycolytic enzymes enzymes is allosterically allosterically regulated? regulated? (a) Glucokinase, phosphofructokinase and pyruvate kinase (b) Hexokinase, aldolase and pyruvate kinase (c) Phosphofructokinase, enolase and pyruvate kinase (d) Hexokinase, phosphofructokinase and pyruvate kinase 2) Which one of the following compounds is required for acetyl coenzyme A (acetyl

CoA)to enter the citric acid cycle? (a) Isocitrate (b (b) Malate (b) Oxaloacetate (d  (d ) Pyruvate 3) Linkag Linkagee present present in cell cellulo ulose se molecul moleculee is (a) b (1 ® 4) (b (b) a ( 1 ® 4) (b) a (1 ®6) (d  ( d ) both (b (b)and (c (c) 4) The largest largest energy energy reserve reserve (in terms of of kilocalorie kilocalories) s) in humans humans is: (a) liver glycogen (b (b) muscle glycogen (b) adipose tissue triacylglycerol. (d  (d ) muscle protein. 5) All the followi following ng compoun compounds ds are Intermedia Intermediate te of the citric citric acid cycle cycle except (a) Isocitrate (b (b) Malate (b) Pyruvate (d  (d ) Succinate 6) Starch digesti digestion on is more more efficient efficient after heating heating the the starch with with water because because heating: heating: (a) hydrat hydrates es the starch starch granul granules, es, making making them them more more suscep susceptib tible le to pancre pancreatic atic amylase. (b) partly hydrolyses a-1, 6 links. (c) converts the linear amylose to branched amylopectin, which resembles glycogen. (d ) inactivates amylase inhibitors, which are common in the tissues of starchy plants. 7) Cellul Cellulose ose is a ____ _____ _ made made of many many ___ _____. __. (a) polypeptide (a)  polypeptide . . . monomers monomers (b) carbohydrate . . . fatty acids (c)  polymer . . . glucose molecules (d) protein (d)  protein . . . amino acids 8) How cellul cellulose ose and starch starch are differe different nt (a) Cellulose molecules are much too large. (b) Starch is made of glucose; cellulose is made of other sugars. (c) The bonds between sugars in cellulose are much stronger. (d) The The suga sugars rs in cell cellul ulos osee bond bond toge togeth ther er diffe differe rent ntly ly than than in starc starch, h, givi giving ng cellulose a different shape. 9) In glycoly glycolysis sis ATP synth synthesis esis is cataly catalyzed zed by: by: (a) hexokinase. (b) 6-phosphofructo-I-kinase. (c) glyceraldehyde 3-phosphate dehydrogenase. (d) phosphoglycerate (d)  phosphoglycerate kinase.

10) The irreversible reactions of glycolysis include that catalyzed by: (a) phosphoglucose isomerase. (b) 6-phosphofructo-l-kinase. (c) fructose bisphosphate aldolase. (d) glyceraldehyde 3-phosphate dehydrogenase. 11) Glucokinase: (a) has a Km considerably greater than the normal blood glucose concentration. (b) is inhibited by glucose 6-phosphate. (c) is also known as the GLUT-2 protein. (d) has glucose 6-phosphatase activity as well as kinase activity. 12) In the Cori cycle: (a) only tissues with aerobic metabolism (i.e., mitochondrial O2) are involved. (b) a three-carbon compound arising from glycolysis is converted to glucose at the expense of energy from fatty acid oxidation. (c) glucose is converted to lactate in anaerobic tissues this lactate returns to the liver, where it is converted into glucose. (d ) the same amount of ATP is used in the liver to synthesis glucose as it is released during glycolysis, leading to no net loss on whole-body energy balance. 13) Gluconeogenic enzymes include all of the following EXCEPT (a) glucose 6-phosphatase. (b) phosphoenolpyruvate carboxykinase. (c)  phosphoglucomutase. (d) pyruvate carboxylase. 14) Glycosaminoglycans: (a) are the carbohydrate portion of glycoproteins, (b) contain large segments of a repeating unit typically consisting of a hexosamine and a uronic acid. (c) always contain sulfate. (d ) exist in only two forms. 15) All of the following statements about acetyl-CoA carboxylase are correct EXCEPT: (a) it undergoes protomer-polymer interconversion during its physiological regulation. (b) it is inhibited by cAMP-mediated phosphorylation. (c) it is activated by both palmitoyl CoA and citrate. (d ) its content in a cell responds to changes in fat content in the diet. 16) The reduction of pyruvate to lactic acid during fermentation allows glycolysis to continue in the absence of oxygen. Why? (a) Water is formed during this reaction (b) This reaction is a kinase reaction (c) This reaction is coupled to the oxidation of NADH to NAD+ (d) This reaction is coupled to the reduction of NAD+ to NADH 17) Acetyl CoA enters the TCA cycle by combining with: (a) oxaloacetate. (b) succinate. (b) citrate. (d ) alpha-ketogluterate.