BIOL 150 Chapter 7 Questions

True or false: Pyruvate oxidation is remarkably similar to glycolysis in that when one molecule of pyruvate enters into a mitochondrion, two molecules of acetyl-CoA are formed.

False When one glucose molecule enters the glycolysis stage, two molecules of pyruvate are formed. When one molecule of pyruvate enters pyruvate oxidation in the mitochondrial matrix, it is converted into one molecule of acetyl-CoA when part of the one pyruvate molecule is oxidized and has some that splits into carbon dioxide.

True or False: Oxidation is the gain of electrons.

False.

True or False: During the action of ATP synthase, the kinetic energy of the proton gradient is transformed into potential energy.

False. Reduced electron carriers NADH and FADH2 are produced from the complete oxidation of glucose during the first three stages of cellular respiration. Energy in these electron carriers is used to synthesize ATP energy. Energy in these electron carriers is released in a series of redox reactions that occur as electrons pass through a chain of protein complexes in the inner mitochondrial matrix to the final protein acceptor oxygen. Energy released from these redox reactions are not converted directly into the chemical energy of ATP. Instead, the passage of electrons is coupled to the transfer of protons across the inner mitochondrial matrix which creates a charge gradient and provides a source of potential energy that is then used to drive the synthesis of ATP.

True or False: Malate is both the starting and ending product of the citric acid cycle.

False. The citric acid cycle takes the acetyl-coenzyme A and further oxidizes it in the mitochondrial matrix. It starts with oxyloacetate which is then regenerated in the end. Oxaloacetate binds with acetyl-CoA to form the 6-carbon citric acid. The newly formed molecule of citric acid is then oxidized in a series of reactions and the last reactions of the cycle regenerates a molecule of ovaloacetate which can then join to a new acetyl group.

In cellular respiration, oxygen: a. gains electrons and is an oxidizing agent b. loses electrons and is a reducing agent. c. gains electrons and is a reducing agent d. loses electrons and is an oxidizing agent e. none of the other answer options is correct

a. gains electrons and is an oxidizing agent

Proteins can be broken down for energy. They are typically broken down into amino acids when then enter cellular respiration by: a. glycolysis or the citric acid cycle b. lactic acid fermentation or the citric acid cycle c. glycolysis or ethanol fermentation d. electron transport/oxidative phosphorylation

a. glycolysis or the citric acid cycle STUDY THIS

True or false: Although glycolysis produces four molecules of ATP by substrate-level phosphorylation, the net gain of ATP for the cell is two molecules. This is due to the fact that glycolysis is-at first-endergonic.

True An endergonic process is a process where the ΔG is positive because the process needs an input of energy to work. To provide the supply of energy that glycolysis needs to go through phase one, two molecules of ATP are hydrolyzed per molecule of glucose.

After pyruvate oxidation, the chemical energy of how many carbons of the original glucose molecule is converted to chemical energy in the form of ATP in the remaining steps of cellular respiration? a. 4 b. 5 c. 1 d. 2 e. 3

a. 4

Pyruvate oxidation is an important stage in cellular respiration because: a. it links glycolysis with the citric acid cycle b. it transfers large numbers of electrons to electron carriers c. it is the first step in oxidative phosphorylation d. it generates ATP by substrate-level phosphorylation e. it eliminates toxic pyruvate from the cell

a. it links glycolysis with the citric acid cycle Pyruvate oxidation is the second part of the citric acid cycle which comes after glycolysis and before the citric acid cycle. Two molecules of pyruvate are produced per one molecule of glucose that enters glycolysis. Pyruvate oxidation is where pyruvate becomes oxidized to become acetyl-CoA which is acetyl-coenzyme A. Pyruvate has to go through this stage because pyruvate still has a lot of chemical potential energy in its bonds and when pyruvate is in the presence of oxygen it can be further oxidized. It happens in the mitochondria matrix.

In cellular respiration, glucose is ___ to CO2 and oxygen is ___ to water. a. oxidized; reduced b. reduced; oxidized c. oxidized; oxidized d. phosphorylated; deoxygenated e. deoxygenated; phosphorylated

a. oxidized; reduced

In the second phase of glycolysis: a. phosphorylated sugar molecule is cleaved and the products rearranged b. ATP is generated by oxidative phosphorylation c. ATP is generated by substrate-level phosphorylation d. phosphate groups are added to glucose e. NAD+ is reduced to NADH

a. phosphorylated sugar molecule is cleaved and the products rearranged

Which of the following statements is true regarding pyruvate oxidation? a. pyruvate oxidation forms the same number of NADH (per glucose molecule) as glycolysis b. pyruvate oxidation ends with the oxidation of an acetyl group which forms CO2 c. pyruvate oxidation directly follows the citric acid cycle during cellular respiration d. like glycolysis, pyruvate oxidation is carried out in the mitochondria

a. pyruvate oxidation forms the same number of NADH (per glucose molecule) as glycolysis Part of the pyruvate molecule is oxidized and splits off to form carbon dioxide. The electrons that are lost in the process are donated to NADH+ which is reduced to NADH. The remaining is then transferred into coenzyme A which can then be further oxidized. It cannot be choice b, because the acetyl group itself does not form CO2. It is the transformation of pyruvate into acetyl-CoA in the mitochondrial matrix. It cannot be c, because pyruvate oxidation comes before the citric acid cycle. It cannot be d, because glycolysis occurs in the cytoplasm.

How did the earliest organisms on earth most likely produce ATP? a. by pyruvate oxidation b. by glycolysis c. by oxidative phosphorylation d. by the citric acid cycle

b. by glycolysis

Phosphorylating glucose during phase 1 of glycolysis: a. releases phosphorylated glucose from cells b. destabilizes the glucose molecule so that it can be broken down in phase 2 c. provides electrons to reduce NAD+ in phase 3 d. provides electrons to reduce FADH in phase 3 e. none of the other answer options are correct

b. destabilizes the glucose molecule s that it can be broken down in phase 2

Phosphorylating glucose during phase 1 of glycolysis: a. releases phosphorylated glucose from cells b. destabilizes the glucose molecule so that it can be broken down in phase 2 c. provides electrons to reduce NAD+ in phase 3 d. provides electrons to reduce FADH in phase 3 e. none of the other answer options is correct

b. destabilizes the glucose molecule so that it can be broken down in phase 2

The final electron acceptor of the electron transport chain is: a. cytochrome C b. oxygen c. coenzyme Q d. NAD+ e. ATP synthase

b. oxygen

The ___ forms of the electron carriers NAD+/NADH and FADH/FADH2 have high potential energy. a. oxidized b. reduced c. phosphorylated d. carboxylated e. none of the other answer options are correct.

b. reduced When something is reduced, it is gaining electrons. When there are more electrons, it is more unstable and wants to react.

Which of the following is not one of the net final products of glycolysis? a. two molecules of pyruvate b. two molecules of acetyl-CoA c. two molecules of NADH d. two molecules of ATP

b. two molecules of acetyl-CoA Phase three of glycolysis is the payoff phase. After phase two (the cleavage phase) where the 6-carbon molecule is split into two 3-carbon molecules, four molecules of ATP are produced and two molecules of NADH are produced as well as two pyruvate. There is net total of a production of two ATP because two ATP were used to begin the reaction.

At the end of glycolysis, the carbon molecules originally found in the starting glucose molecule are in the form of: a. one pyruvate molecule b. two pyruvate molecules c. four ATP molecules d. two ATP molecules e. two NADH molecules

b. two pyruvate molecules

The inputs to glycolysis do not include: a. Pi b. ADP c. NADH d. NAD+ e. glucose

c. NADH STUDY THIS

Which of the following statements is true regarding the equation C6H12O6 + 6O2 ---> 6CO2+6H2O+energy? a. The movement of hydrogen atoms in reactions involving C6H12O6 and H2O yields no information regarding the movement of electrons. b. The oxygen atoms in both CO2 and H2O are electronegative. c. The oxygen atoms in both CO2 and H2O are electronegative, and glucose is considered a reducing agent. d. Glucose could be considered a reducing agent. e. In the production of CO2 from glucose, the oxygen atoms lose electrons and the carbon atom is oxidized.

c. The oxygen atoms in both CO2 and H2O are electronegative and glucose is considered a reducing agent. STUDY THIS

A beer maker is using yeast to make his favorite brew. How does yeast produce ethanol? a. through the reduction of lactic acid b. directly from the reduction of glucose c. through the reduction of acetaldehyde, derived from pyruvate d. through the oxidation of acetaldehyde, derive from pyruvate e. through the direct reduction of pyruvate, similar to lactic acid fermentation

c. Through the reduction of acetaldehyde, derive from pyruvate. Fermentation happens when there is not enough oxygen to keep up with the work of the body. Glycolysis does not need oxygen, so pyruvate is made which means pyruvate can be used. Ethanol fermentation happens when pyruvate releases carbon dioxide to form acetaldehyde produce ethanol and NAD+. STUDY THIS

Lactic acid fermentation occurs in: Select all that apply. a. fungi and bacteria b. animals and fungi c. bacteria and animals d. plants and bacteria e. animals and plants

c. bacteria and animals Lactic acid fermentation occurs in animals and bacterias.

In the first three stages of cellular respiration, the chemical energy in glucose is transferred to: a. only coenzyme Q b. ATP and cytochrome b c. electron carriers and ATP d. proton pumps and ATP e. cytochrome b and coenzyme Q

c. electron carriers and ATP

Imagine that a eukaryotic cell carries a mutation impairing its ability to phosphorylate glucose during glycolysis. What is a likely result of this mutation? a. more pyruvate would be formed at the end of glycolysis b. high (possibly toxic) glucose would accumulate in the cell c. glucose could move out of the cell, slowing cellular respiration d. without the phosphorylation of glucose, glycolysis would consist entirely of exergonic reactions e. because phosphorylation stabilizes glucose, glucose would spontaneously form pyruvate

c. glucose could move out of the cell, slowing cellular respiration

____ is found in animals, and possesses a large, central protein. ____ is found in plants, and lacks a central protein. a. glycogen; glycogen also b. starch; glycogen c. glycogen; starch d. starch; starch also

c. glycogen; starch When there is too much glucose, glucose in animals is stored as glycogen in either the liver or the muscles or glucose in plants is stored as starch.

Which of the following correctly characterizes the F1 subunit of ATP synthase? a. it is embedded in the inner mitochondrial membrane b. it forms the channel through which protons flow c. it is the catalytic unit that synthesizes ATP d. none of the other answer options is correct

c. it is the catalytic unit that synthesizes ATP F0 is the catalytic unit that forms the channel through which protons flow.

If you've ever learned about beer making, you make know that some people add fruit juice to their yeast mixtures. Why? a. to facilitate oxidative phosphorylation b. to provide an additional source of yeast which will make the beer more potent c. to provide glucose to the yeast d. to provide materials for an alternate, aerobic respiration pathway e. to both facilitate oxidative phosphorylation and to provide an additional source of yeast

c. to provide glucose to the yeast

Beta-oxidation of fatty acids does not directly produce: a. acetyl-CoA b. electrons transferred to NAD+ c. electrons transferred to FADH d. ATP

d. ATP Beta oxidation shortens fatty acids in the process of using triacylglycerol as a source of energy. Beta oxidation is a series of reactions that sequentially remove two carbon units from their ends. It does does produce ATP, but releases a large amount of NADH and FADH2 molecules that provide electrons for the synthesis of ATP by oxidative phosphorylation.

An electron from NADH entering the electron transport chain would travel among components of the chain in what sequence? a. complex II, coenzyme !, complex IV, cytochrome C, ATP synthase, oxygen b. complex I, coenzyme Q, complex II, cytochrome C, complex III, coenzyme Q, complex IV, cytochrome C, oxygen c. complex II, cytochrome C, complex IV, cytochrome C, oxygen d. complex I, coenzyme Q, complex III, cytochrome C, complex IV, oxygen e. complex I, coenzyme Q, complex III, cytochrome C, ATP synthase, oxygen

d. complex I, coenzyme Q, complex III, cytochrome C, complex IV, oxygen The electron transport chain transfers electrons and pumps protons and is formed by a series of four large protein complexes that electrons donated by NADH and FADH2 transport along. Electrons enter the electron transport chain at either complex 1 or 2. If an electron comes from NADH it enters through complex 1. IF an electron comes from NADH2 it enters at complex 2. After entering the chain through either of those complexes, the electron goes to complex III then IV. Within each protein complex electrons are transported from electron donors to electron acceptors and each donor and acceptor is a redox couple. Coenzyme Q is the enzyme that accepts electrons from both complexes I and II. Two electrons and two protons are transferred to coenzyme Q from the mitochondrial matrix forming COQU2 which diffuses in the inner membrane to complex III.

The first phase of glycolysis requires the input of two ATP molecules. It is therefore: a. none of the other answer options is correct b. oxidative c. reducing d. endergonic c. exergonic

d. endergonic

Due to the pumping action of the electron transport chain, protons have a high concentration in the ___ and a low concentration in the ___. a. mitochondrial matrix; cytoplasm b. mitochondrial matrix; inter membrane space c. mitochondrial matrix; extracellular fluid d. inter membrane space; mitochondrial matrix e. inter membrane space; cytoplasm

d. inter membrane space; mitochondrial matrix A protein gradient is a source of potential energy from the difference in protein concentration across the inner membrane. The electron transport chain causes protons to have a high concentration in the inter membrane space and low concentration in mitochondrial matrix.

During pyruvate oxidation, pyruvate is broken down into CO2 and an acetyl group. The CO2 is: a. less oxidized than the acetyl group b. more reduced than the acetyl group c. more energetic than the acetyl group d. less energetic than the acetyl group e. none of the other answer options is correct

d. less energetic than the acetyl group

Which is the only reaction in the citric acid cycle that produces ATP by substrate-level phosphorylation? a. the formation of oxaloacetate b. the formation of citrate c. the formation of fumarate d. the formation of malate e. the formation of succinate

e. The formation of succinate STUDY THIS

During pyruvate oxidation, which of the following also occur(s)? a. the formation of NADH b. the oxidation of pyruvate c. the formation of acetyl-CoA d. the formation of CO2 e. all of these answer choices are correct

e. all of these answer choices are correct

Which of the following statements are true regarding pyruvate oxidation? a. this process occurs within the matrix or the mitochondria b. this process constitutes the second stage of cellular respiration b. the process produces both CO2 and acetyl-CoA d. the process yields no ATP via substrate-level phosphorylation e. all of these choices are correct

e. all of these choices are correct

In which of the following organisms would you expect ethanol fermentation to occur? a. bacteria b. fungi c. animals d. plants e. fungi and plants

e. fungi and plants

Excess glucose is stored in large branched molecules of: a. glycogen and starch in both animals and plants b. glycogen in plants c. starch in animals d. starch in bacteria e. glycogen in animals

e. glycogen in animals

The chemical bonds of carbohydrates and lipids have high potential energy because: a. they are strong reducing agents b. they are easy to hydrolyze c. they are easy to phosphorylate d. they are strong oxidizing agents e. many of these are C-C and C-H bonds

e. many of these are C-C and C-H bonds

Which of the following statements is true regarding pyruvate and glucose? a. glucose easily passes in and out of mitochondria, and can often be found in the mitochondrial matrix b. pyruvate is typically "trapped" in the inter membrane space of mitochondria c. glucose and pyruvate are remarkably similar in structure with both molecules possessing a ring shape d. both glucose and pyruvate can feed directly into the citric acid cycle, although acetyl-CoA is the preferred reactant for this process e. none of the other answer options are correct

e. none of the other answer options is correct

Which of the following is not an end product for an acetyl group that enters the citric acid cycle? a. NADH b. ATP c. FADH2 d. CO2 e. oxaloacetate

e. oxaloacetate An acetyl group that is derived from a pyruvate enters the citric acid cycle, which then pairs with an oxaloacetate.

A molecule that is ____ loses electrons, and a molecule that is ____ gains electrons. a. none of the other answer options are correct b. weak; polar c. negative; positive d. reduced; oxidized e. oxidized; reduced

e. oxidized; reduced

Which of the following does not occur during the third phase of glycolysis? a. ATP synthesis b. pyruvate production c. the transfer of high-energy electrons to NAD+ d. none of the other answer options is correct e. oxygen consumption

e. oxygen consumption STUDY THIS

Recall that the citric acid cycle starts with a four-carbon molecule, but that most of its intermediates are molecules that contain six carbons. How is this possible? a. through the reaction of citrate and cis-aconitate b. through the reaction of malate and fumarate c. through the reaction of succinate and succinyl-CoA? d. through the reaction of malate and oxaloacetate e. through the reaction of acetyl-CoA and oxaloacetate

e. through the reaction of acetyl-CoA and oxaloacectate