CH4

41) Changes in environmental pH or temperature will cause the reaction rate for an enzyme to A) increase. B) decrease. C) either increase or decrease depending upon enzyme properties. D) not change.

C

13) An allosteric modulator binds to A) a region of the enzyme other than the active site. B) the active site. C) the substrate. D) the product. E) the surrounding tissue.

A

2) According to the second law of thermodynamics, A) the amount of entropy in living systems increases without the input of energy. B) entropy decreases in living systems that are not receiving energy. C) energy can be converted, but not be created nor destroyed. D) the total amount of energy in the universe never changes.

A

34) Transcription occurs in the ________ of the cell. A) nucleus B) cytoplasm C) Golgi apparatus D) smooth endoplasmic reticulum E) plasma membrane

A

40) The rate of product formation by an enzyme-catalyzed reaction would be increased by A) adding more substrate molecules. B) adding more product molecules. C) reducing the number of enzymes. D) reducing the number of substrate molecules.

A

47) The protein in the mitochondria that captures the kinetic energy of moving H+ ions and converts it to the stored energy of ATP is called A) ATP synthase. B) lactate dehydrogenase. C) oxidative phosphorylase. D) glucokinase.

A

49) Transcription of the DNA triplet sequence ATC yields A) UAG. B) TAG. C) UTC. D) ATC.

A

6) Isozymes A) are enzymes with a slightly different structure that catalyze the same reaction. B) are enzymes with the same structure that catalyze different reactions. C) are inorganic molecules that bind to and thereby activate enzymes. D) are the inactive form of an enzyme.

A

7) Enzymes increase reaction rate by A) lowering the activation energy of a reaction. B) increasing the free energy in the products. C) raising the activation energy of a reaction. D) converting an endergonic reaction to an exergonic reaction.

A

12) A competitive inhibitor binds to A) a region of the enzyme other than the active site. B) the active site. C) the substrate. D) the product. E) the surrounding tissue.

B

16) A molecule that loses electrons during a reaction is A) reduced. B) oxidized. C) dehydrated. D) hydrated.

B

20) When energy is released during catabolism, it is temporarily trapped in high energy bonds or electrons of certain compounds. Which of the following is NOT associated with carrying energy? A) ATP B) DNA C) NADH D) FADH2 E) NADPH

B

23) In the aerobic metabolism of glucose, ________ acts as the final electron acceptor. A) water B) oxygen C) carbon dioxide D) lactate E) ATP

B

26) What is the potential yield of ATP molecules for each FADH2 molecule entering the electron transport system? A) 1 B) 1.5 C) 2 D) 2.5 E) 3

B

27) Why is there a range of 30-32 ATP molecules produced from one glucose molecule? A) Sometimes the electron transport system is more efficient than other times. B) The NADH molecules produced during glycolysis are in the cytoplasm; occasionally, electrons are carried by the lower energy FADH2 instead of NADH. C) Individual variation is normal among cells. D) Any of these answers may work under different cellular conditions.

B

30) The process of forming mRNA is called A) replication. B) transcription. C) translation. D) ribolation. E) protein synthesis.

B

32) All of the triplet codes needed to produce exactly one functional piece of RNA are found in one A) chromosome. B) gene. C) codon. D) anticodon. E) None of the answers are correct.

B

35) The enzymes that synthesize mRNA from the start codon are called A) ribonucleases. B) RNA polymerases. C) DNA polymerases. D) ATP synthases. E) lactate dehydrogenases.

B

37) The tRNA molecule contains the three-base sequence called the A) codon. B) anticodon. C) semicodon. D) aminocodon.

B

38) A molecule positioned on the high-concentration side of a concentration gradient stores ________ energy. A) chemical B) potential C) kinetic

B

43) Which of the following is a key intermediate of glucose catabolism to the citric acid cycle? A) ATP B) pyruvate C) oxygen D) lactate E) glucokinase

B

5) A reversible reaction is one where A) there are large changes in the net free energy from substrate to product. B) there are small changes in the net free energy from substrate to product. C) there is no change in the net free energy from substrate to product. D) a reaction between products is unlikely due to the high activation energy.

B

4) Activation energy is A) the energy lost or gained in a reaction. B) the energy required for an endergonic reaction. C) the energy required to bring molecules into a position where they can interact. D) required to convert an endergonic reaction to an exergonic reaction.

C

) Organic molecules that act as receptors/carriers for the cleaved portion of the substrate are A) vitamins. B) isoenzymes. C) coenzymes. D) modulators.

C

) What happens to the oxygen that is metabolized within the mitochondria? A) The oxygen is converted to CO2. B) The oxygen is incorporated into organic molecules during cellular metabolism. C) The oxygen is combined with hydrogen to form water. D) The oxygen acts as a coenzyme in the production of ATP. E) The oxygen is converted to CO2 and is combined with hydrogen to form water.

C

14) An enzyme that transfers chemical groups among substrates is a A) hydrolase. B) lipase. C) transferase. D) ligase. E) kinase.

C

17) When an enzyme is working as fast as it can because its active site is continually refilled with substrate, the condition is referred to as A) allosteric modulation. B) equilibrium. C) saturation. D) the Ricardo-Mertz phenomenon. E) specificity.

C

22) The reactions of glycolysis occur in the cell's ________; the reactions of the citric acid cycle occur in the ________. A) cytoplasm, cytoplasm B) mitochondria, mitochondria C) cytoplasm, mitochondria D) mitochondria, cytoplasm

C

25) For each NADH molecule that moves through the electron transport system, what is the potential yield of ATP molecules? A) 1 B) 2 C) 2.5 D) 3.5 E) 4

C

33) Information stored in the nucleus is translated into A) carbohydrates. B) lipids. C) proteins. D) phospholipids. E) None of the answers are correct.

C

44) The net energy yield for the anaerobic metabolism of one glucose molecule is A) 2 ATP and 2 NADH. B) 0 ATP and 2 NADH. C) 2 ATP and 0 NADH. D) 2 ATP and 2 FADH2. E) 2 ATP, 6 NADH, and 2 FADH2.

C

46) Oxidative phosphorylation occurs ________; the beneficial end product is ________. A) in the cytoplasm just inside the plasma membrane, H2O B) in the cytoplasm just inside the plasma membrane, ATP C) in the mitochondria due to the electron transport system, ATP D) in the mitochondria due to the electron transport system, CO2 E) twice during the citric acid cycle, ATP

C

9) The activity of an enzyme is changed by environmental factors such as temperature or pH; these factors are referred to as A) specificity. B) common bond. C) modulators. D) isozyme. E) product.

C

10) The addition of a phosphate group to a substrate is called ________. The enzyme that catalyzes this reaction is referred to as a ________. A) proteolysis, phosphatase B) phosphorylation, phosphatase C) proteolysis, kinase D) phosphorylation, kinase

D

18) Which of these results in a REDUCED molecule? A) loss of phosphate B) gain of phosphate C) loss of electrons D) gain of electrons

D

19) End-product inhibition describes the process whereby A) decreasing amounts of substrate reduce activity of the enzyme. B) decreasing amounts of product reduce activity of the enzyme. C) increasing amounts of substrate reduce activity of the enzyme. D) increasing amounts of product reduce activity of the enzyme.

D

21) Aerobic metabolism of glucose A) requires oxygen. B) produces more ATP per glucose than anaerobic pathways. C) is the fastest way to produce glucose. D) requires oxygen and produces more ATP per glucose than anaerobic pathways.

D

24) The explanation for how ATP bonds are actually formed during oxidative phosphorylation is called A) the Krebs hypothesis. B) the second law of thermodynamics. C) the proton principle. D) the chemiosmotic theory. E) Murphy's law.

D

29) ATP synthase transfers the ______ energy of the H+ ions to the high-energy phosphate bond of _____. A) potential, NADH B) potential, ATP C) kinetic, NADH D) kinetic, ATP E) None of the answers are correct.

D

3) The ________ of glycogen from many glucose molecules is an ________ reaction. A) decomposition, endergonic B) synthesis, exergonic C) decomposition, exergonic D) synthesis, endergonic

D

31) After forming a complex with the ribosome, mRNA interacts with a third molecule. This molecule is called A) DNA. B) an amino acid. C) rRNA. D) tRNA. E) rough ER.

D

39) How would the lack of a required cofactor for an enzyme affect that enzyme's function? A) The enzyme's function would not be altered. B) The enzyme would function more slowly. C) The enzyme would function more quickly. D) The enzyme would not be able to function.

D

50) During starvation, steroid hormones trigger the transcription of genes for lipid metabolism in their target cells. This would be an example of control by A) negative feedback. B) positive feedback. C) repressors. D) inducers. E) alternative splicing.

D

_15) An enzyme that joins two substrates using energy is a A) hydrolase. B) lipase. C) transferase. D) ligase. E) kinase.

D

____36) Once synthesized, the ________ of mRNA are removed through ________, which results in the formation of the coding sequence of a protein. A) exon, RNA interference B) exon, alternative splicing C) intron, RNA interference D) intron, alternative splicing

D

____45) NADH is produced from each reaction described EXCEPT one. Identify the exception. A) during aerobic glycolysis B) during the conversion of pyruvate to acetyl CoA C) during the citric acid cycle D) during anaerobic glycolysis

D

11) When an enzyme's activity is destroyed by heat or a change in pH, the enzyme is said to be A) broken. B) toxic. C) conjugated. D) tertiary. E) denatured.

E

28) Which can serve as substrates for ATP production? A) glucose only B) amino acids only C) fatty acids only D) glucose and fatty acids only E) glucose, amino acids and fatty acids

E

____1) The general term that describes energy stored in chemical bonds is A) thermodynamics. B) bioenergetics. C) entropy. D) kinetic energy. E) potential energy.

E