Chapter 7 Mastering Bio

Glycolysis produces how many ATP?

2 ATP, 2 NADH, and 2 pyruvate molecules

Which statement about the citric acid cycle is correct? 1. The citric acid cycle oxidizes glucose to carbon dioxide. 2 The citric acid cycle produces most of the ATP that is subsequently used by the electron transport chain. 3 The citric acid cycle depends on the availability of NAD+, which is a product of glycolysis. 4 The last reaction in the citric acid cycle produces a product that is a substrate for the first reaction of the citric acid cycle. 5 The oxidation of compounds by the citric acid cycle requires molecular oxygen.

4

Which of the following statements describes the results of this reaction? C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy A) C6H12O6 is oxidized and O2 is reduced. B) O2 is oxidized and H2O is reduced. C) CO2 is reduced and O2 is oxidized. D) C6H12O6is reduced and CO2 is oxidized. E) O2 is reduced and CO2 is oxidized.

A

During aerobic respiration, H2O is formed. Where does the oxygen atom for the formation of the water come from? A. glucose B. carbon dioxide C. pyruvate D. lactate E. molecular oxygen

E

In the process of glycolysis during cellular respiration, what is consumed and what is produced? Carbon dioxide is consumed, and water is produced. ATP is consumed, and oxygen is produced. Glucose is consumed, and carbon dioxide is produced. Oxygen is consumed, and glucose is produced. Water is consumed, and ATP is produced.

Glucose is consumed, and carbon dioxide is produced.

In cellular respiration, most ATP molecules are produced by _____. substrate-level phosphorylation cellular respiration photosynthesis oxidative phosphorylation photophosphorylation

oxidative phosphorylation

One function of both alcohol fermentation and lactic acid fermentation is to oxidize NADH to NAD+. reduce FADH2 to FAD+. reduce FAD+ to FADH2. reduce NAD+ to NADH. do none of the above.

oxidize NADH to NAD+

The final electron acceptor of cellular respiration is _____. oxygen NADH FADH2 water CO2

oxygen

20. For each glucose molecule that enters glycolysis, how many ATP, NADH, and FADH2 are produced in the citric acid cycle?

two ATP, six NADH, two FADH2

Which of the following statements about the chemiosmotic synthesis of ATP is correct? 1 The energy for production of ATP from ADP comes directly from a gradient of electrons across the inner mitochondrial membrane. 2 Oxygen participates directly in the reaction that makes ATP from ADP and P. 3 The chemiosmotic synthesis of ATP requires that the electron transport in the inner mitochondrial membrane be coupled to proton transport across the same membrane. 4 The chemiosmotic synthesis of ATP occurs only in eukaryotic cells, because it occurs in mitochondria. 5 Chemiosmotic ATP synthesis requires oxygen.

3

Which one of the following statements about the redox reactions of the electron transport chain is correct? 1 NADH gains electrons in the initial reaction of the electron transport chain. 2 The electron transport chain takes electrons from water and gives them to oxygen. 3 The oxidation of NADH is directly coupled to the reduction of oxygen to water. 4 The redox reactions of the electron transport chain are directly coupled to the movement of protons across a membrane. 5 The redox reactions of the electron transport chain are directly coupled with the synthesis of ATP

4

For each glucose that enters glycolysis, _____ NADH + H+ are produced by the citric acid cycle. For each glucose that enters glycolysis, _____ NADH + H+ are produced by the citric acid cycle. 3 to 6 0 3 2 6

6

Which of the following statements is not true of most cellular redox reactions? View Available Hint(s) The reactant that is oxidized loses electrons. A hydrogen atom is transferred to the atom that loses an electron. Changes in potential energy can be released as heat. The electron acceptor is reduced.

A hydrogen atom is transferred to the atom that loses an electron.

Which terms describe two atoms when they form a bond in which electrons are completely transferred from one atom to the other? Proton and electron. Anion and cation. Polar and nonpolar. Ionic and covalent.

Anion and cation.

Why does the oxidation of organic compounds by molecular oxygen to produce CO2 and water release free energy? A) The covalent bonds in organic molecules are higher energy bonds than those in water and carbon dioxide. B) Electrons are being moved from atoms that have a lower affinity for electrons (such as C) to atoms with a higher affinity for electrons (such as O). C) The oxidation of organic compounds can be used to make ATP. D) The electrons have a higher potential energy when associated with water and CO2 than they do in organic compounds. E) The covalent bond in O2 is unstable and easily broken by electrons from organic molecules.

B

How would anaerobic conditions (when no O2 is present) affect the rate of electron transport and ATP production during oxidative phosphorylation? (Note that you should not consider the effect on ATP synthesis in glycolysis or the citric acid cycle.) View Available Hint(s) Neither electron transport nor ATP synthesis would be affected. Electron transport would stop but ATP synthesis would be unaffected. Electron transport would be unaffected but ATP synthesis would stop. Both electron transport and ATP synthesis would stop.

Both electron transport and ATP synthesis would stop. Oxygen plays an essential role in cellular respiration because it is the final electron acceptor for the entire process. Without O2, mitochondria are unable to oxidize the NADH and FADH2 produced in the first three steps of cellular respiration, and thus cannot make any ATP via oxidative phosphorylation. In addition, without O2 the mitochondria cannot oxidize the NADH and FADH2 back to NAD+ and FAD, which are needed as inputs to the first three stages of cellular respiration.

NADH and FADH2 are both electron carriers that donate their electrons to the electron transport chain. The electrons ultimately reduce O2 to water in the final step of electron transport. However, the amount of ATP made by electrons from an NADH molecule is greater than the amount made by electrons from an FADH2 molecule. Which statement best explains why more ATP is made per molecule of NADH than per molecule of FADH2? FADH2 is made only in the citric acid cycle while NADH is made in glycolysis, acetyl CoA formation, and the citric acid cycle. It takes more energy to make ATP from ADP and Pi using FADH2 than using NADH. Fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron donor. There is more NADH than FADH2 made for every glucose that enters cellular respiration. The H+ gradient made from electron transport using NADH is located in a different part of the mitochondrion than the H+ gradient made using FADH2.

Fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron donor.

hydrogen burns in the presence of oxygen to form water: 2H2 + O2 → 2H2 O + energy Which molecule is oxidized and what kind of bond is formed? 2H2 + O2 → 2H2 O + energy Which molecule is oxidized and what kind of bond is formed? Oxygen, nonpolar. Hydrogen, polar. Hydrogen, nonpolar. Oxygen, polar.

Hydrogen, polar.

A glucose molecule is completely broken down to carbon dioxide and water in glycolysis and the citric acid cycle, but together these two processes yield only a few molecules of ATP. What happened to most of the energy that the cell obtains from the oxidation of glucose? It is stored in NADH and FADH2 It is stored in the ATP that was formed by glycolysis and the citric acid cycle. It is stored in the carbon dioxide and water molecules released by these processes. It is stored in pyruvate. It was lost as heat.

It is stored in NADH and FADH2 The electrons obtained from the oxidation of glucose are temporarily stored in NADH and FADH2. The energy derived from the oxidation of NADH and FADH2 is used to drive the electron transport chain and chemiosmotic synthesis of ATP.

Which of the following describes the process of glycolysis? Glycolysis produces 30 ATP from each molecule of glucose. It requires ATP and NADH. It represents the first stage in the chemical oxidation of glucose by a cell. It converts one glucose molecule to two molecules of pyruvate and carbon dioxide. Glycolysis occurs in the mitochondria.

It represents the first stage in the chemical oxidation of glucose by a cell.

Why is glycolysis described as having an investment phase and a payoff phase? It attaches and detaches phosphate groups. It both splits molecules and assembles molecules. It shifts molecules from cytosol to mitochondrion. It uses stored ATP and then forms a net increase in ATP. It uses glucose and generates pyruvate.

It uses stored ATP and then forms a net increase in ATP.

During electron transport, energy from _____ is used to pump hydrogen ions into the _____.

NADH and FADH2 ... intermembrane space (The energy released as electrons, which have been donated by NADH and FADH2, is passed along the electron transport chain and used to pump hydrogen ions into the intermembrane space.)

Which of the following statements is true of the bonds in a water molecule? View Available Hint(s) The electron in each hydrogen atom is completely transferred to the oxygen atom, and each hydrogen atom has a net charge of +1. There is equal sharing of the electrons between the oxygen atom and the two hydrogen atoms, and the net charge is zero. Oxygen acts as the electron acceptor and is oxidized. Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero.

Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero. The oxygen and hydrogen atoms in water have partial charges, but the molecule has a net charge of zero.

Why are carbohydrates and fats considered high-energy foods? They can have very long carbon skeletons. They have a lot of electrons associated with hydrogen. They have no nitrogen in their makeup. They are easily reduced. They have a lot of oxygen atoms.

They have a lot of electrons associated with hydrogen.

In cellular respiration, the energy for most ATP synthesis is supplied by converting oxygen to ATP. a proton gradient across a membrane. generating carbon dioxide and oxygen in the electron transport chain. transferring electrons from organic molecules to pyruvate. high-energy phosphate bonds in organic molecules.

a proton gradient across a membrane.

Which of these is NOT a product of the citric acid cycle? Which of these is NOT a product of the citric acid cycle? CO2 FADH2 acetyl CoA ATP NADH + H+

acetyl CoA

The primary role of oxygen in cellular respiration is to combine with carbon, forming CO2. catalyze the reactions of glycolysis. act as an acceptor for electrons and hydrogen, forming water. yield energy in the form of ATP as it is passed down the respiratory chain. combine with lactate, forming pyruvate.

act as an acceptor for electrons and hydrogen, forming water

21) During aerobic respiration, electrons travel downhill in which sequence? a) food → citric acid cycle → ATP → NAD+ b) food → NADH → electron transport chain → oxygen c) glucose → pyruvate → ATP → oxygen d) glucose → ATP → electron transport chain → NADH e) food → glycolysis → citric acid cycle → NADH → ATP

b) food → NADH → electron transport chain → oxygen

22. How many molecules of ATP are gained by substrate-level phosphorylation from the complete breakdown of a single molecule of glucose in the presence of oxygen?

four

What carbon sources can yeast cells metabolize to make ATP from ADP under anaerobic conditions? lactic acid ethanol glucose pyruvate either ethanol or lactic acid

glucose

Which process in eukaryotic cells will proceed normally whether oxygen (O2) is present or absent? glycolysis electron transport chemiosmosis the citric acid cycle oxidative phosphorylation

glycolysis

What kind of bond is formed when lithium and fluorine combine to form lithium fluoride? View Available Hint(s) What kind of bond is formed when lithium and fluorine combine to form lithium fluoride? Ionic. Redox. Nonpolar covalent. Polar covalent.

ionic

The proximate (immediate) source of energy for oxidative phosphorylation is _____.

kinetic energy that is released as hydrogen ions diffuse down their concentration gradient (Concentration gradients are a form of potential energy.)

In muscle cells, fermentation produces _____. lactate and NAD+ pyruvate carbon dioxide, ethanol, NADH, and ATP carbon dioxide, ethanol, and NAD+

lactate and NAD+

In fermentation _____ is reduced and _____ is oxidized. lactate ... NADH pyruvate ... NADH lactate ... ethanol NADH ... lactate NAD+ ... pyruvate

pyruvate ... NADH The pyruvate from glycolysis is reduced to either lactate or ethanol, and NADH is oxidized to NAD+.

In alcohol fermentation, NAD+ is regenerated from NADH by oxidation of pyruvate to acetyl CoA. oxidation of ethanol to acetyl CoA. reduction of ethanol to pyruvate. reduction of pyruvate to form lactate. reduction of acetaldehyde to ethanol (ethyl alcohol).

reduction of acetaldehyde to ethanol (ethyl alcohol).

When the protein gramicidin is integrated into a membrane, an H+ channel forms and the membrane becomes very permeable to protons (H+ ions). If gramicidin is added to an actively respiring muscle cell, how would it affect the rates of electron transport, proton pumping, and ATP synthesis in oxidative phosphorylation? (Assume that gramicidin does not affect the production of NADH and FADH2 during the early stages of cellular respiration.)

remains the same: proton pumping rate, electron transport rate, rate of oxygen uptake. decreases or goes to zero: rate of ATP synthesis, size of protein gradient Gramicidin causes membranes to become very leaky to protons, so that a proton gradient cannot be maintained and ATP synthesis stops. However, the leakiness of the membrane has no effect on the ability of electron transport to pump protons. Thus, the rates of proton pumping, electron transport, and oxygen uptake remain unchanged.

In the citric acid cycle, ATP molecules are produced by _____. oxidative phosphorylation photophosphorylation photosynthesis cellular respiration substrate-level phosphorylation

substrate-level phosphorylation

The ATP made during fermentation is generated by which of the following? substrate-level phosphorylation aerobic respiration oxidative phosphorylation the electron transport chain chemiosmosis

substrate-level phosphorylation

In mitochondrial electron transport, what is the direct role of O2? to provide the driving force for the synthesis of ATP from ADP and Pi to oxidize NADH and FADH2 from glycolysis, acetyl CoA formation, and the citric acid cycle to provide the driving force for the production of a proton gradient to function as the final electron acceptor in the electron transport chain

to function as the final electron acceptor in the electron transport chain The only place that O2 participates in cellular respiration is at the end of the electron transport chain, as the final electron acceptor. Oxygen's high affinity for electrons ensures its success in this role. Its contributions to driving electron transport, forming a proton gradient, and synthesizing ATP are all indirect effects of its role as the terminal electron acceptor.

hich of the following best describes the main purpose of the combined processes of glycolysis and cellular respiration? catabolism of sugars and related compounds producing complex molecules from chemical building blocks transforming the energy in glucose and related molecules in a chemical form that cells can use for work breaking down ATP, so that ADP and P can be reused the breakdown of glucose to carbon dioxide and water

transforming the energy in glucose and related molecules in a chemical form that cells can use for work

The Krebs cycle produces what?

two molecules of ATP for every molecule of glucose. The Krebs cycle also produces six molecules of NADH and two molecules of FADH2 per molecule of glucose. four CO2.

The electrons stripped from glucose in cellular respiration end up in which compound? oxygen NADH ATP carbon dioxide water

water At the end of the electron transport chain, the electrons and protons are added to oxygen, forming water.