front 1 What is the change in free energy of a system at chemical equilibrium? | back 1 no net change |
front 2 Most cells cannot harness heat to perform work because | back 2 temperature is usually uniform throughout a cell. |
front 3 Competitive inhibitors block the entry of substrate into the active site of an enzyme. On which of the following properties of an active site does this primarily depend? | back 3 the ability of an enzyme to form a template for holding and joining molecules |
front 4 Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's | back 4 activation energy |
front 5 The mathematical expression for the change in free energy of a system is G =H-T S. Which of the following is (are) correct? | back 5 G is the change in free energy. |
front 6 For living organisms, which of the following is an important consequence of the first law of thermodynamics? | back 6 The organism ultimately must obtain all of the necessary energy for life from its environment. |
front 7 Which of the following is true of metabolism in its entirety? | back 7 Metabolism is a property of organismal life |
front 8 Which of the following statements regarding enzymes is true? | back 8 Enzymes increase the rate of a reaction. |
front 9 In order to attach a particular amino acid to the tRNA molecule that will transport it, an enzyme, an aminoacyl-tRNA synthetase, is required, along with ATP. Initially, the enzyme has an active site for ATP and another for the amino acid, but it is not able to attach the tRNA. What must occur in order for the final attachment to occur? | back 9 The binding of the first two molecules must cause a 3-dimensional change that opens another active site on the enzyme. |
front 10 Which of the following statements is representative of the second law of thermodynamics? | back 10 Cells require a constant input of energy to maintain their high level of organization. |
front 11 Which of the following statements is (are) true about enzyme-catalyzed reactions? | back 11 The reaction is faster than the same reaction in the absence of the enzyme. |
front 12 An important group of peripheral membrane proteins are enzymes, such as the phospholipases that attack the head groups of phospholipids leading to the degradation of damaged membranes. What properties must these enzymes exhibit? | back 12 water solubility |
front 13 When ATP releases some energy, it also releases inorganic phosphate. What purpose does this serve (if any) in the cell? | back 13 It can be added to other molecules in order to activate them. |
front 14 Zinc, an essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. The zinc most likely functions as a(n) | back 14 cofactor necessary for enzyme activity. |
front 15 What term is used to describe the transfer of free energy from catabolic pathways to anabolic pathways? | back 15 energy coupling |
front 16 Which of the following is most similar in structure to ATP? | back 16 an RNA nucleotide |
front 17 The following questions are based on the reaction A + B C + D shown in Figure 8.2. Which of the following bests describes the reaction? | back 17 negative G, spontaneous |
front 18 The following questions are based on the reaction A + B C + D shown in Figure 8.2. Which of the following represents the G of the reaction? | back 18 d |
front 19 Which of the following statements is a logical consequence of the second law of thermodynamics? | back 19 Every chemical reaction must increase the total entropy of the universe. |
front 20 When 10,000 molecules of ATP are hydrolyzed to ADP and Pi in a test tube, about twice as much heat is liberated as when a cell hydrolyzes the same amount of ATP. Which of the following is the best explanation for this observation? | back 20 Reactant and product concentrations are not the same |
front 21 During a laboratory experiment, you discover that an enzyme-catalyzed reaction has a G of -20 kcal/mol. If you double the amount of enzyme in the reaction, what will be the G for the new reaction? | back 21 -20 kcal/mol |
front 22 According to the induced fit hypothesis of enzyme catalysis, which of the following is correct? | back 22 The binding of the substrate changes the shape of the enzyme's active site. |
front 23 Chemical equilibrium is relatively rare in living cells. Which of the following could be an example of a reaction at chemical equilibrium in a cell? | back 23 a chemical reaction in which both the reactants and products are only used in a metabolic pathway that is completely inactive |
front 24 How can one increase the rate of a chemical reaction? | back 24 Add a catalyst. |
front 25 Living organisms increase in complexity as they grow, resulting in a decrease in the entropy of an organism. How does this relate to the second law of thermodynamics? | back 25 As a consequence of growing, organisms create more disorder in their environment than the decrease in entropy associated with their growth. |
front 26 Which of the following is considered an open system? | back 26 an organism |
front 27 The organization of organisms has become increasingly complex with time. This statement | back 27 is consistent with the second law of thermodynamics. |
front 28 Sucrose is a disaccharide, composed of the monosaccharides glucose and fructose. The hydrolysis of sucrose by the enzyme sucrase results in | back 28 breaking the bond between glucose and fructose and forming new bonds from the atoms of water. |
front 29 Which of the following statements is true concerning catabolic pathways? | back 29 They are usually coupled with anabolic pathways to which they supply energy in the form of ATP. |
front 30 A chemical reaction that has a positive G is correctly described as | back 30 endergonic |
front 31 Increasing the substrate concentration in an enzymatic reaction could overcome which of the following? | back 31 competitive inhibition |
front 32 Refer to Figure 8.1 to answer the following questions. Which curve was most likely generated from analysis of an enzyme from a human stomach where conditions are strongly acid? | back 32 curve 4 |
front 33 Which of the following is (are) true for anabolic pathways? | back 33 Which of the following is (are) true for anabolic pathways? |
front 34 Which of the following is an example of potential rather than kinetic energy? | back 34 a food molecule made up of energy-rich macromolecules |
front 35 Whenever energy is transformed, there is always an increase in the | back 35 entropy of the universe |
front 36 What must be the difference (if any) between the structure of ATP and the structure of the precursor of the A nucleotide in DNA and RNA? | back 36 There is no difference |
front 37 Refer to Figure 8.1 to answer the following questions. Which curve was most likely generated from an enzyme that requires a cofactor? | back 37 It is not possible to determine whether an enzyme requires a cofactor from these data. |
front 38 A solution of starch at room temperature does not readily decompose to form a solution of simple sugars because | back 38 the activation energy barrier for this reaction cannot be surmounted. |
front 39 How does a noncompetitive inhibitor decrease the rate of an enzyme reaction? | back 39 by changing the shape of a reactant |
front 40
The next questions are based on the following information. What is substance X? | back 40 a substrate |