Module 3 - Metabolism

Which statement about glycolysis is true? a) It splits water b) It produces FADH2 c) It occurs in the cytosol d) It makes the most ATP compared to the other steps in the breakdown of glucose e) It splits lipid

c) It occurs in the cytosol

Which of the following statements best describes the accompanying figure? a) It represents an adaptation that maximizes photorespiration. b) It represents a C3 photosynthetic system. c) It represents a C4 photosynthetic system. d) It represents a CAM photosynthetic system.

c) It represents a C4 photosynthetic system.

How do living organisms create macromolecules, organelles, cells, tissues, and complex higher-order structures? a) The laws of thermodynamics do not apply to living organisms b) Living organisms create order by recycling and reusing energy from the sun c) Living organisms create order locally, but the energy transformation generate waste heat that increases the entropy of the universe

c) Living organisms create order locally, but the energy transformation generate waste heat that increases the entropy of the universe

Upon completion of the citric acid cycle, most of the energy originally stored in each glucose molecule catabolized by cellular respiration is stored in which of the following molecules? a) acetyl-CoA b) ATP c) NADH d) CO2

c) NADH

Which of the following products result from the oxidation of pyruvate to acetyl-CoA? a) O2 and ATP b) FADH2 and CO2 c) NADH and CO2 d) NAD+, ATP and CO2

c) NADH and CO2

A reaction has a ∆G of +1 kcal/mol. Which of the following would most likely be true? a) The reaction is at equilibrium. b) The reaction would proceed by itself but might be very slow. c) The reaction is nonspontaneous. d) The reaction could be coupled to power an endergonic reaction.

c) The reaction is nonspontaneous.

Which of the following metabolic processes normally occurs in most cells regardless of oxygen (O2) availability? a) citric acid cycle b) oxidative phosphorylation c) glycolysis d) lactate fermentation

c) glycolysis

Which of the following reactions produces the majority of the CO2 released by the complete oxidation of glucose? a) glycolysis b) oxidation of pyruvate to acetyl-CoA c) the citric acid cycle d) electron transport

c) the citric acid cycle

When a cell is deprived of oxygen, which of the following processes will be inhibited first? a) the citric acid cycle b) glycolysis c) the electron transport chain d) the oxidation of pyruvate to acetyl CoA

c) the electron transport chain

The reaction has a delta G of -5.6 kcal/mol. Which of the following would most likely be true? a) The reaction could be coupled to power an endergonic reaction with a delta G of +8.8 kcal/mol b) The reaction is nonspontaneous c) To take place, the reaction would need to couple to ATP hydrolysis d) The reaction would result in product with a greater free energy content than in the initial reactant e) The reaction would proceed by itself but might be very slow

e) The reaction would proceed by itself but might be very slow

The citric acid cycle. For each mole of glucose (C6H12O6) oxidized by cellular respiration, how many moles of CO2 are released in the citric acid cycle (see the accompanying figure)? a) 6 b) 32 c) 2 d) 4

4

The light reactions of photosynthesis use _____ and produce _____.

water ... NADPH

Which of the following sequences correctly represents the flow of electrons during photosynthesis?

H2O→ NADPH → Calvin cycle

Which of these equations best summarizes photosynthesis?

6 CO2 + 6 H2O → C6H12O6 + 6 O2

Because ______ plants have Bundle-sheath cells, they are able to ________ separate their Calvin Cycle from high concentrations of _______.

C4; spatially; O2

Where does the Calvin cycle occur?

E Stroma

What is the correct sequence of compounds an electron would encounter if you begin from the very start of Photosystem II and use non-cyclic electron flow? I Ferredoxin II Water III NADPH IV G3P V Pheophytin

II-V-I-III-IV

reduction of NADP+ oxidation of electron transport chain between the 2 photosystems

PSI only

oxidation of water reduction of electron transport chain between the 2 photosystems

PSII only

If glucose is the sole energy source for cellular respiration in an animal, what proportion of the carbon dioxide exhaled is derived from oxidation of pyruvate to acetyl CoA? a) 1/3 b) 1/6 c) 2/3 d) 100%

a) 1/3

Drugs known as uncouplers facilitate diffusion of protons across the membrane. With an uncoupler, what will happen to ATP synthesis and oxygen consumption if the rates of glycolysis and the citric acid cycle stay the same? a) ATP synthesis will decrease; oxygen consumption will stay roughly the same. c) Both ATP synthesis and oxygen consumption will increase. d) ATP synthesis will decrease; oxygen consumption will greatly increase. d) Both ATP synthesis and oxygen consumption will decrease.ATP synthesis will increase; oxygen consumption will decrease.

a) ATP synthesis will decrease; oxygen consumption will stay roughly the same.

Which of the following statements best describes enzyme function? a) Enzymes increase the rate of chemical reactions by lowering activation energy barriers. b) Enzyme function is independent of physical and chemical environmental factors such as pH and temperature. d) Enzyme function is generally increased if the 3-D structure or conformation of an enzyme is altered. d) Enzymes increase the rate of chemical reactions by stimulating ATP hydrolysis.

a) Enzymes increase the rate of chemical reactions by lowering activation energy barriers.

What would happen to cytoplasmic enzyme activity inside a cell with a normal cytoplasmic pH of 7.2 if you injected a chemical that would change the pH to 4.0? a) Enzymes would probably denature. b) Enzymatic activity would increase substantially. c) Enzymes would start to add ATP to all reactions. d) Little or no change would occur.

a) Enzymes would probably denature.

Which of the following statements best describes the primary role played by oxygen in cellular respiration? a) It serves as the final acceptor for electrons from the electron transport chain. b) It yields energy in the form of ATP as it is passed down the electron transport chain. c) It serves as an acceptor for carbon, forming CO2 in the citric acid cycle. d) It oxidizes glucose to form two molecules of pyruvate.

a) It serves as the final acceptor for electrons from the electron transport chain.

Which of the following statements best describes how addition of a catalyst will affect a chemical reaction? a) The catalyzed reaction will have the same ΔG as the uncatalyzed reaction. b) The catalyzed reaction will have a lower ΔG than the uncatalyzed reaction. c) The catalyzed reaction will consume all of the catalyst. d) The catalyzed reaction will have a higher ΔG than the uncatalyzed reaction.

a) The catalyzed reaction will have the same ΔG as the uncatalyzed reaction.

Which of the following statements best describes catabolic pathways? a) They are exergonic and provide energy that can be used to produce ATP from ADP and Pi. b) They require energy from ATP hydrolysis to break down polymers into monomers. c) They combine small molecules into larger, more energy-rich molecules. d) They are endergonic and release energy that can be used for cellular work.

a) They are exergonic and provide energy that can be used to produce ATP from ADP and Pi.

ATP synthase at the inner mitochondrial membrane makes ATP and water from ADP and phosphate by coupling this to which other process? a) allowing H+ to move down its electrochemical gradient b) allowing H+ to move against its electrochemical gradient c) active transport of H+ d) synthesis of H+

a) allowing H+ to move down its electrochemical gradient

A decrease in entropy is associated with which of the following types of reaction? a) dehydration b) catabolic c) depolymerization d) hydrolysis

a) dehydration

Which of the following statements describes a primary function of both alcohol fermentation and lactic acid fermentation? a) oxidation of NADH to NAD+ b) hydrolysis of ATP to ADP + Pi c) reduction of NAD+ to NADH d) reduction of FAD to FADH2

a) oxidation of NADH to NAD+

Glycolysis results in the net production of which of the following sets of molecules per glucose molecule? a) 2 NAD+, 2 pyruvate, and 2 ATP b) 2 NADH, 2 pyruvate, and 2 ATP c) 4 NADH, 2 pyruvate, and 4 ATP d) 6 CO2, 2 pyruvate, and 2 ATP

b) 2 NADH, 2 pyruvate, and 2 ATP

Which of the following statements best summarizes the metabolic results of photorespiration? a) ATP is hydrolyzed, oxygen is produced, and carbon dioxide is consumed. b) ATP is hydrolyzed, carbon dioxide is produced, and oxygen is consumed. c) ATP and oxygen are produced and carbon dioxide is consumed. d) ATP is produced, oxygen and carbon dioxide are consumed.

b) ATP is hydrolyzed, carbon dioxide is produced, and oxygen is consumed.

Which of the following statements best describes the central role that ATP plays in cellular metabolism? a) Hydrolysis of ATP provides an input of free energy for exergonic reactions. b) ATP provides energy coupling between exergonic and endergonic reactions. c) Hydrolysis of the terminal phosphate group from ATP stores free energy that is used for cellular work. d) The terminal phosphate bond is stronger than most covalent bonds in other biological macromolecules.

b) ATP provides energy coupling between exergonic and endergonic reactions.

Which statement about the Citric Acid cycle is true? a) It occurs during the movement from the cytosol through the mitochondrial membranes b) It makes ATP through substrate-level phosphorylation c) It makes the most ATP compared to the other steps in the breakdown of glucose d) It occurs in the eukaryotic cytoplasm e) It splits glucose

b) It makes ATP through substrate-level phosphorylation

Which of the following statements best explains the ability of CAM plants to synthesize sugars in the daytime while keeping their stomata closed to reduce water loss? a) They fix CO2 into sugars in the bundle-sheath cells. b) They fix CO2 into organic acids during the night. c) They fix CO2 into pyruvate in the mesophyll cells. d) They use photosystem I and photosystem II at night.

b) They fix CO2 into organic acids during the night.

In which reactions of cellular respiration does substrate-level phosphorylation occur? a) only in glycolysis b) in both glycolysis and the citric acid cycle c) only in the citric acid cycle d) only in the electron transport chain

b) in both glycolysis and the citric acid cycle

Energy released from the electron transport chain is used to pump H+ ions into which location in eukaryotic cells? a) cytoplasm adjacent to the mitochondrial outer membrane b) mitochondrial intermembrane space c) mitochondrial matrix d) mitochondrial inner membrane

b) mitochondrial intermembrane space

reduction of primary electron acceptor light absorption

both PSI and PSII

Which of the following events takes place in the electron transport chain? a) the breakdown of glucose into six carbon dioxide molecules b) substrate-level phosphorylation c) the harnessing of energy from redox reactions to generate a proton gradient d) the breakdown of an acetyl group to carbon dioxide

c) the harnessing of energy from redox reactions to generate a proton gradient

What is the purpose of fermentation reactions? a) to slow down cellular oxygen consumption when oxygen is scarce b) to make additional ATP when respiration can't make ATP fast enough c) to regenerate NAD+ so glycolysis can continue d) to make organic molecules that cells can store until oxygen becomes available e) to make alcohol or lactic acid that cells can metabolize for energy under anaerobic conditions

c) to regenerate NAD+ so glycolysis can continue

Which of the following statements best describes an exergonic reaction? a) The reaction goes only in a forward direction: all reactants will be converted to products, but no products will be converted to reactants. b) The products have more total energy than the reactants. c) A net input of energy from the surroundings is required for the reaction to proceed. d) The reaction proceeds with a net release of free energy.

d) The reaction proceeds with a net release of free energy.

An enzyme-catalyzed reaction has a ΔG of -20 kcal/mol under standard conditions. What will be the ΔG for the reaction if the amount of enzyme is doubled? a) -40 kcal/mol b) -10 kcal/mol c) +20 kcal/mol d) -20 kcal/mol

d) -20 kcal/mol

If a cell produces on average 30 ATP molecules for each molecule of glucose that is completely oxidized to carbon dioxide and water, how many ATP molecules on average can the cell synthesize for each molecule of pyruvate oxidized to carbon dioxide and water? a) 14 b) 8 c) 25 d) 12.5

d) 12.5

Approximately how many molecules of ATP are produced from the complete oxidation of one molecule of glucose (C6H12O6) in aerobic cellular respiration? a) 18-24 b) 2 c) 4 d) 30-32

d) 30-32

Which of the summary statements below best describes the results of the following reaction? C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy a) O2 is oxidized and H2O is reduced. b) CO2 is reduced and O2 is oxidized. c) O2 is reduced and CO2 is oxidized. d) C6H12O6 is oxidized and O2 is reduced.

d) C6H12O6 is oxidized and O2 is reduced.

Which of the following statements best describes the electron transport chain? a) It occurs in the cytoplasm of both prokaryotic and eukaryotic cells. b) It is driven by ATP hydrolysis. c) It includes a series of hydrolysis reactions associated with mitochondrial membranes. d) It consists of a series of redox reactions.

d) It consists of a series of redox reactions.

The standard free energy for the complete oxidation of glucose to CO2 and water is -686 kcal/mol, and the standard free energy for the reduction of NAD+ to NADH is +53 kcal/mol. Which of the following statements best explains why only two molecules of NADH are formed in glycolysis when up to 12 molecules could theoretically be produced? a) There is no CO2 or water produced as products of glycolysis. b) Glycolysis is a very inefficient process, with much of the energy of glucose released as heat. c) Most of the free energy available from the oxidation of glucose is used in the production of ATP in glycolysis. d) Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis.

d) Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis.

Which of the following statements best describes what happens to a molecule of NAD+ (nicotinamide adenine dinucleotide) when it gains a hydrogen atom? a) NAD+ becomes ionized. b) NAD+ becomes oxidized. c) NAD+ becomes dehydrogenated. d) NAD+ becomes reduced.

d) NAD+ becomes reduced.

Which of the following statements best describes a characteristic of NAD+? a) NAD+ is oxidized in glycolysis to produce ATP. b) NAD+ may donate electrons for use in oxidative phosphorylation. c) NAD+ stores more chemical energy than NADH. d) NAD+ is reduced to NADH in glycolysis, pyruvate oxidation, and the citric acid cycle.

d) NAD+ is reduced to NADH in glycolysis, pyruvate oxidation, and the citric acid cycle

Which of the following is a characteristic feature of anabolic pathways? a) They decrease the entropy of the organism and its environment. b) They release energy by degrading polymers to monomers. c) They are usually spontaneous chemical reactions. d) They consume energy to build up polymers from monomers.

d) They consume energy to build up polymers from monomers.

Which of the following statements best explains the ability of C4 plants to perform photosynthesis with no apparent photorespiration? a) They do not participate in the Calvin cycle. b) They exclude oxygen from their tissues. c) They conserve water more efficiently. d) They use PEP carboxylase to initially fix CO2.

d) They use PEP carboxylase to initially fix CO2.

What do cells require to sustain high rates of glycolysis under anaerobic conditions? a) To consume oxygen. b) To generate enough pyruvate for cells to survive. c) To support high rate of oxidative phosphorylation. d) Under anaerobic conditions, cells depend on the low-efficient fermentation pathway to generate ATP.

d) Under anaerobic conditions, cells depend on the low-efficient fermentation pathway to generate ATP.

Some enzymes can couple the hydrolysis of ATP to ion transport by having a) energy from ATP hydrolysis alter the free energy changes of another reaction. b) phosphate groups from the ATP temporarily donated to the ions. c) the coupled processes both be exergonic. d) changes during ATP hydrolysis alter the enzyme's shape, forcing ionic transport to occur.

d) changes during ATP hydrolysis alter the enzyme's shape, forcing ionic transport to occur.

Which of the following metabolic processes take place in the cytosol of a eukaryotic cell? a) oxidation of pyruvate to acetyl CoA b) fermentation and chemiosmosis c) citric acid cycle d) glycolysis and fermentation

d) glycolysis and fermentation

When electrons are passed from one atom to a more electronegative atom, the more electronegative atom is ________. a) oxidized, and energy is used b) reduced, and energy is used c) oxidized, and energy is released d) reduced, and energy is released

d) reduced, and energy is released