Mastering Biology Chapter 7

Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed by the electron transport chain?

0%

Starting with one molecule of isocitrate and ending with fumarate, how many ATP molecules can be made through substrate-level phosphorylation (see the figure)? 11 2 1 24 12

1

How many NADH are produced by glycolysis? 4 1 2 3 5

2

In glycolysis there is a net gain of _____ ATP. 3 5 2 4 1

2

Approximately how many molecules of ATP are produced from the complete oxidation of two molecules of glucose (C6H12O6) in aerobic cellular respiration? 15 2 30-32 60-64 4

60-64

In glycolysis, what starts the process of glucose oxidation? ATP NADPH ADP hexokinase FADH2

ATP

Where in mitochondria is the enzyme ATP synthase localized? mitochondrial matrix inner membrane electron transport chain outer membrane

inner membrane

Which metabolic pathway generates a proton gradient? glycolysis chemiosmosis the oxidation of pyruvate to acetyl CoA the citric acid cycle the electron transport chain

the electron transport chain

Which of the following best describes the main purpose of the combined processes of glycolysis and cellular respiration? breaking down ATP so that ADP and P can be reused producing complex molecules from chemical building blocks catabolism of sugars and related compounds 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

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

In a mitochondrion, if the matrix ATP concentration is high and the intermembrane space proton concentration is too low to generate sufficient proton-motive force, then ATP synthase will increase the rate of ATP synthesis. ATP synthase will synthesize ATP and pump protons into the intermembrane space. ATP synthase will hydrolyze ATP and pump protons into the matrix. ATP synthase will synthesize ATP and pump protons into the matrix. ATP synthase will hydrolyze ATP and pump protons into the intermembrane space.

ATP synthase will hydrolyze ATP and pump protons into the intermembrane space.

Select the correct statement about cellular respiration. Animals carry out cellular respiration whereas plants carry out photosynthesis. Plants carry out cellular respiration only in organs such as roots that cannot carry out photosynthesis. Cellular respiration and breathing differ in that cellular respiration is at the cellular level, whereas breathing is at the organismal level.

Cellular respiration and breathing differ in that cellular respiration is at the cellular level, whereas breathing is at the organismal level.

Which of the following is an accurate description of the events that occur along the electron transport chain depicted in the figure? The potential energy of electrons increases at each step in the pathway. Electron transfer is directly coupled to chemiosmosis. ATP is generated directly at three points in the pathway. Each electron transfer between carriers results in oxidation of one carrier and reduction of another.

Each electron transfer between carriers results in oxidation of one carrier and reduction of another.

Why is glycolysis described as having an energy investment phase and an energy payoff phase? Early steps consume energy from ATP, and later steps store an increased amount of energy in ATP and NADH. Early steps consume energy from NADH, and later steps store an increased amount of energy in ATP and NADH. Early steps consume energy from ATP and NADH and later steps store an increased amount of energy in ATP. Early steps consume energy from ATP and NADH, and later steps store an increased amount of energy in ATP and NADH. Early steps consume energy from ATP and NADH, and later steps store an equal amount of energy in ATP and NAD+.

Early steps consume energy from ATP, and later steps store an increased amount of energy in ATP and NADH

Why does the oxidation of organic compounds by molecular oxygen to produce CO2 and water release free energy? The covalent bond in O2 is unstable and easily broken by electrons from organic molecules. The covalent bonds in organic molecules and molecular oxygen have more kinetic energy than the covalent bonds in water and carbon dioxide. The oxidation of organic compounds releases less energy than the energy stored in the covalent bonds of CO2 and water. The electrons have higher potential energy when associated with water and CO2 than they do in the organic compounds. 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).

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).

Which of these is NOT a product of glycolysis? pyruvate ATP NADH FADH2

FADH2

In the combined processes of glycolysis and cellular respiration, what is consumed, and what 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. Carbon dioxide is consumed, and water is produced.

Glucose is consumed, and carbon dioxide is produced.

Which of the following statements about NAD+ is true? NAD+ is the source of electrons used in oxidative phosphorylation. NAD+ is oxidized by the action of dehydrogenase enzymes. NAD+ has more chemical energy than NADH. NAD+ is reduced to NADH during glycolysis.

NAD+ is reduced to NADH during glycolysis.

In addition to ATP, what are the end products of glycolysis? CO2 and NADH H2O, FADH2, and citrate NADH and pyruvate CO2 and pyruvate CO2 and H2O

NADH and pyruvate

If pyruvate oxidation is blocked, what will happen to the levels of oxaloacetate and citrate in the citric acid cycle shown in the figure? Oxaloacetate will decrease and citrate will accumulate. There will be no change in the levels of oxaloacetate and citrate. Both oxaloacetate and citrate will accumulate. Both oxaloacetate and citrate will decrease. Oxaloacetate will accumulate and citrate will decrease.

Oxaloacetate will accumulate and citrate will decrease.

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

The chemiosmotic synthesis of ATP requires that the electron transport in the inner mitochondrial membrane be coupled to proton transport across the same membrane.

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

The last reaction in the citric acid cycle produces a product that is a substrate for the first reaction of the citric acid cycle.

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

Water

Which of these enters the citric acid cycle? NADH + H+ G3P acetyl CoA pyruvate glucose

acetyl CoA

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

acetyl CoA

Which one of the following is formed by the removal of a carbon (as CO2) from a molecule of pyruvate? glyceraldehyde-3-phosphate acetyl CoA citrate oxaloacetate lactate

acetyl CoA

During intense exercise, as skeletal muscle cells switch to fermentation, the human body will increase its catabolism of fats, carbohydrates, and proteins. carbohydrates only. fats only. proteins only. fats and proteins only.

carbohydrates only.

Which of the following indicates a primary path by which electrons travel downhill energetically during aerobic respiration? glucose → glycolysis → electron transport chain → NADH → ATP glucose → citric acid cycle → ATP → NAD+ glucose → pyruvate → acetyl CoA → ATP → oxygen glucose → NADH → electron transport chain → oxygen glucose → glycolysis → citric acid cycle → NADH → ATP

glucose → NADH → electron transport chain → oxygen

complete oxidation of glucose in aerobic respiration occurs through which of the following sequence of metabolic reactions? glucose → pyruvate oxidation → citric acid cycle → glycolysis → electron transport chain glucose → glycolysis → pyruvate oxidation → citric acid cycle → electron transport chain glucose → pyruvate oxidation → glycolysis → electron transport chain → citric acid cycle glucose → citric acid cycle → glycolysis → pyruvate oxidation → electron transport chain glucose → glycolysis → citric acid cycle → pyruvate oxidation → electron transport chain

glucose → glycolysis → pyruvate oxidation → citric acid cycle → electron transport chain

Which metabolic pathway is common to both cellular respiration and fermentation? glycolysis oxidative phosphorylation the oxidation of pyruvate to acetyl CoA the citric acid cycle chemiosmosis

glycolysis

Which of the following occur(s) in the cytosol of a eukaryotic cell? glycolysis and fermentation oxidation of pyruvate to acetyl CoA citric acid cycle oxidative phosphorylation fermentation and chemiosmosis

glycolysis and fermentation

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

lactate and NAD+

In an oxidation-reduction reaction, the reducing agent loses electrons and gains potential energy. loses electrons and loses potential energy. gains electrons and gains potential energy. gains electrons and loses potential energy.

loses electrons and loses potential energy.

Where are the proteins of the electron transport chain located? mitochondrial outer membrane cytosol mitochondrial matrix mitochondrial inner membrane mitochondrial intermembrane space

mitochondrial inner membrane

The complete reactions of cellular respiration in the presence of oxygen (C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + energy) result in which of the following? reduction of CO2 and oxidation of O2 reduction of C6H12O6 and oxidation of CO2 oxidation of C6H12O6 and reduction of O2 oxidation of O2 and reduction of H2O

oxidation of C6H12O6 and reduction of O2

One primary function of both alcohol fermentation and lactic acid fermentation is to reduce FADH2 to FAD+. reduce FAD+ to FADH2. reduce NAD+ to NADH. oxidize NADH to NAD+.

oxidize NADH to NAD+.

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

pyruvate ...... NADH

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

reduction of acetaldehyde to ethanol.

The primary role of oxygen in cellular respiration is to donate high energy electrons to the electron transport chain. combine with acetyl CoA, forming pyruvate. serve as an acceptor for electrons and hydrogen, forming water. serve as an acceptor for released carbon, forming CO2.

serve as an acceptor for electrons and hydrogen, forming water.

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

substrate-level phosphorylation

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

substrate-level phosphorylation