Chemistry

Q: Match the vitamin name with its corresponding chemical name.A) thiamineB) cobalaminC) niacinD) cholecalciferolE) ascorbic acidF) riboflavinG) pyridoxine1> vitamin B32> vitamin B23> vitamin B14> vitamin C5> vitamin B126> vitamin B6

Q: Identify the type of inhibition in each description.A) competitiveB) noncompetitive1> an inhibitor that resembles the structure of the substrate2> an inhibitor that forms a covalent bond with a side chain in the active site3> Adding more substrate does not reverse the effect of this inhibitor.4> The inhibition can be reversed by increasing the concentration of substrate.5> The inhibitor does not resemble the substrate.

Q: Identify the effect of the following on the activity of maltase, an enzyme that hydrolyzes maltose.A) decreasesB) increasesC) has no effect1> decreasing the concentration of maltose2> adjusting the temperature to the optimum temperature3> raising the pH to 11.04> increasing the concentration of maltase (enzyme) when the enzyme is saturated with substrate5> lowering the pH to 1.0

Q: Match the correct term in enzyme action with each description.A) coenzymeB) lock-and-key theoryC) cofactorD) active siteE) enzyme-substrate complex1> the temporary combination of an enzyme with the compound on which it acts2> an organic compound that is sometimes needed to complete an enzyme3> the portion of an enzyme molecule where catalytic activity occurs4> an inorganic substance such as Mg2+ required by some enzymes for activity5> one theory that accounts for the unusual specificity of an enzyme

Q: Identify each of the designated regions on the energy diagram for the conversion of a substrate to product with and without an enzyme. 1> energy of the substrate 2> energy of the product 3> activation energy without the enzyme 4> activation energy with the enzyme

Q: Vitamins are often cofactors.

Q: Enzyme cofactors are always metal ions, such as Zn2+ and Fe3+.

Q: Enzymes always require a cofactor.

Q: Insulin and digestive enzymes are produced as inactive forms called zymogens.

Q: Phosphorylation is a common form of covalent modification.

Q: The optimum pH of most cellular enzymes is about 7.4.

Q: Urease is an example of an oxidoreductase enzyme.

Q: Pyruvate carboxylase is an example of a ligase enzyme.

Q: Alanine transaminase is an example of a transferase enzyme.

Q: In the induced fit model of enzyme activity, both the enzyme and the substrate change shape.

Q: The active site is a large part of an enzyme.

Q: Indicate whether each of the following is fat soluble or water soluble. 1> vitamin B6 2> vitamin A 3> pantothenic acid 4> ascorbic acid 5> vitamin E 6> vitamin K 7> niacin 8> folic acid 9> vitamin D 10> riboflavin

Q: A diet very low in vitamin C can lead over time to the condition ________. A) rickets B) scurvy C) cancer D) carpal tunnel syndrome E) anorexia nervosa

Q: One deficiency disease that can be traced to insufficient intake of vitamin D is ________. A) scurvy B) rickets C) beriberi D) pellagra E) pernicious anemia

Q: Another name for a zymogen is a(n) ________. A) cofactor B) coenzyme C) prosthetic group D) isozyme E) proenzyme

Q: The optimum pH for the activity of trypsin is about ________. A) 2.0 B) 4.0 C) 6.5 D) 7.4 E) 8.0

Q: The optimum pH for the activity of pepsin is about ________. A) 2.0 B) 4.0 C) 6.5 D) 7.4 E) 7.6

Q: An enzyme that removes H from a substrate is classified as a(n) ________. A) oxidoreductase B) transferase C) hydrolase D) lyase E) isomerase

Q: Enzymes that catalyze the same reactions but have slightly different structures are called ________. A) coenzymes B) cofactors C) isoenzymes D) competitive E) noncompetitive

Q: The full name of the enzyme LDH is ________. A) lactate dehydrogenase B) liver decompensation hexase C) lactate dehydrase D) liver dihydrogen kinase E) lipase dehydrogenase

Q: An enzyme that converts a cis double bond to a trans double bond is classified as a(n) ________. A) oxidoreductase B) transferase C) hydrolase D) lyase E) isomerase

Q: The names of many enzymes can be recognized by the suffix ________. A) -ate B) -ite C) -ose D) -ine E) -ase

Q: A biological catalyst is called a(n) ________. A) lipid B) enzyme C) cofactor D) coenzyme E) substrate

Q: Coenzymes such as water-soluble vitamins are needed in only small amounts because A) only small amounts of enzymes are present in each cell. B) only small amounts of substrates are available at any one time. C) they can be eliminated in the urine. D) each vitamin molecule can be reused many times as a cofactor. E) they can be stored in the liver for future use.

Q: The B vitamins are examples of A) water-soluble vitamins. B) essential amino acids. C) essential minerals. D) oil soluble vitamins. E) vitamins that are stored in the liver.

Q: Iron(II) and iron(III) ions are used in the functioning of A) urease. B) alcohol dehydrogenase. C) creatine kinase. D) the cytochrome oxidase system. E) pepsin.

Q: When a cofactor is a small organic molecule, it is known as a(n) A) isoenzyme. B) vitamin. C) zymogen. D) coenzyme. E) regulator.

Q: Metal ions such as Zn2+ and Fe3+ are often needed by enzymes as A) isozymes. B) allosteres. C) inhibitors. D) cofactors. E) substrates.

Q: The water-soluble B and C vitamins supply A) essential amino acids. B) substrates necessary for most of the reactions in the body. C) essential fatty acids. D) coenzymes required by some enzymes. E) competitive inhibitors needed to regulate enzyme activity.

Q: A noncompetitive inhibitor A) binds at the active site of the enzyme. B) alters the three-dimensional structure of the enzyme. C) increases the rate of the enzyme-catalyzed reaction. D) has a structure similar to the substrate. E) has its effect reversed by adding more substrate.

Q: Which of the following is NOT true for a competitive inhibitor? A) It occupies the active site. B) It cannot be converted to products. C) It has a structure similar to the substrate. D) Increasing the substrate concentration can reverse competitive inhibition. E) It binds to the enzyme at a site remote from the active site.

Q: Penicillin-resistant bacteria can survive treatment with penicillin because they produce the enzyme A) sucrase. B) penicillin kinase. C) penicillinase. D) bacteriase. E) phosphate lyase.

Q: Some insecticides kill insects by inhibiting the enzyme A) alcohol dehydrogenase. B) acetylcholinesterase. C) creatine kinase. D) lipase. E) penicillinase.

Q: A compound that binds to the surface of an enzyme, and changes its shape so that a substrate cannot enter the active site, is called a(n) A) irreversible inhibitor. B) proenzyme. C) cofactor. D) noncompetitive inhibitor. E) competitive inhibitor.

Q: Penicillin functions as an antibiotic by A) poisoning bacteria with toxins. B) raising the temperature of a bacterium. C) bonding to metal ions in bacterial electron transport systems. D) inhibiting the enzymes for cell wall formation in bacteria. E) acting as an acetylcholinesterase inhibitor.

Q: A noncompetitive inhibitor has a structure that A) does not resemble the substrate structure. B) resembles the active site of the enzyme. C) can bind to the active site of the enzyme. D) does not interfere with the enzyme-substrate complex formation. E) causes a change in the shape of the substrate.

Q: An irreversible inhibitor is one that A) forms hydrogen bonds with the substrate. B) binds to the enzyme with hydrophobic interactions. C) reacts covalently with the substrate. D) binds covalently to the enzyme active site. E) reacts covalently with a cofactor.

Q: A competitive inhibitor is one that A) binds to the enzyme at a site far from the active site. B) binds to the active site in place of the substrate. C) destroys the substrate. D) binds to the allosteric site on an enzyme. E) forms a complex with the substrate.

Q: Allosteric enzymes can control their output of product by A) binding the substrate at a site away from the active site. B) binding an irreversible inhibitor at the active site. C) binding a positive or negative regulator at a noncompetitive site. D) changing the pH in the active site. E) reversible inhibition using the product as the inhibitor.

Q: When an end product from an enzyme-mediated sequence is also an inhibitor for an earlier step in the reaction sequence, the process is referred to as A) feedback control. B) competitive inhibition. C) irreversible inhibition. D) negative catalysis. E) concentration control.

Q: Pepsinogen is an example of a(n) A) coenzyme. B) cofactor. C) isoenzyme. D) allosteric enzyme. E) zymogen.

Q: Urea is converted to ammonia and carbon dioxide by the action of urease. What will be the effect on the rate if the temperature of the reaction is lowered from 37 C (the optimum temperature) to 27 C?A) There will be no effect.B) The rate will slow down.C) The rate will double.D) The rate will triple.E) The rate will slow down, then speed up again.

Q: Consider an enzymatic reaction in which the initial concentration of substrate is low. If the amount of enzyme is held constant, but the amount of substrate is increased, the rate of an enzyme catalyzed reaction will A) increase in an exponential fashion. B) decrease at first, then increase in a linear fashion. C) increase at first in a linear fashion, then remain at a constant high rate. D) stay the same. E) be inhibited by the higher concentrations of substrate.

Q: In an enzyme-substrate reaction, when excess substrate is present, increasing the concentration of the enzyme will A) increase the number of substrate molecules available. B) inhibit the formation of products. C) increase the decomposition rate of the enzyme-substrate complex. D) decrease the turnover rate for the substrate. E) increase the amount of reaction occurring.

Q: The surface of a freshly cut apple turns brown because of A) inhibition of the surface enzymes by nitrogen. B) interaction of the surface enzymes with oxygen. C) a change in pH at the surface. D) an increase in substrate concentration at the cut surface. E) the presence of vitamin C in the apple.

Q: Most enzymes are deactivated permanently above a temperature of about A) 25 C. B) 37 F. C) 40 C. D) 45 F. E) 50 C.

Q: "Physiological pH", the pH for optimum activity for most enzymes, is a pH equal to A) 3.0. B) 5.4. C) 7.4. D) 8.6. E) 9.0.

Q: "Physiological conditions" for reactions within the body are approximately A) pH 3 and 37 C. B) pH 7 and 37 C. C) pH 7 and 37 F. D) pH 8 and 273 C. E) pH 7 and 273 K.

Q: The optimum temperature for sucrase activity is 37 C. The hydrolysis of sucrose is slowest at which temperature in the choices below? A) 0 C B) 10 C C) 20 C D) 25 C E) 45 C

Q: The hydrolysis of ester bonds in triglycerides is catalyzed by a(n) A) lipase. B) lyase. C) isomerase. D) hydrolase. E) oxidoreductase.

Q: To what main class of enzymes does the enzyme that catalyzes the following reaction belong? Ser - Ala â†’ Ser + Ala A) oxidoreductase B) transferase C) hydrolase D) lyase E) isomerase

Q: To what main class of enzymes does the enzyme that catalyzes the following reaction belong?A) oxidoreductaseB) transferaseC) hydrolaseD) lyaseE) isomerase

Q: To what main class of enzymes does the enzyme that catalyzes the conversion of lactose to galactose and glucose belong? A) oxidoreductase B) transferase C) hydrolase D) lyase E) isomerase

Q: Creatine kinase can be used in the diagnosis of A) hepatitis. B) rickets. C) heart attack. D) prostatitis. E) cancer.

Q: An increase in concentration of the enzyme LDH in the blood can be used to detect A) heart attack. B) kidney damage. C) anemia. D) uremia. E) bulimia.

Q: How many generalized steps are there in the reaction of an enzyme (E) with a substrate (S) to form and release the product (P)? A) one B) two C) three D) four E) five

Q: The function of the enzyme-substrate complex is to provide an alternative reaction pathway that A) lowers the energy of the products. B) lowers the energy of the substrate. C) changes the concentration of the substrate. D) decreases the activation energy for the reaction. E) changes the possible product formed.

Q: In the induced-fit model of enzyme action, the enzyme active site A) stays the same shape during substrate binding. B) adjusts shape to adapt to the shape of the substrate. C) stays the same shape while causing a change in the shape of the substrate. D) uses an inhibitor to adjust its shape for the substrate. E) uses a cofactor to change the shape of a substrate.

Q: In the lock-and-key model of enzyme action, the enzyme active site is thought of as A) a rigid, nonflexible shape that fits the substrate exactly. B) an area of the enzyme that can adjust to fit the substrate shape. C) a key-like shape that fits into a pocket of the substrate surface. D) a hydrophilic area on the enzyme surface. E) a lock that bars a noncompetitive inhibitor from reacting.

Q: Hexokinase catalyzes only the addition of phosphate to any hexose sugar. This type of activity is called A) regional specificity. B) collateral specificity. C) group specificity. D) noncompetitive specificity. E) general specificity.

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