BIOL 1100 Chapter 7

Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed by the electron transport chain? 0% 2% 10% 38% 100%

0%

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

NAD+ is reduced to NADH during glycolysis.

Which metabolic pathway generates a proton gradient? the citric acid cycle chemiosmosis the oxidation of pyruvate to acetyl CoA glycolysis 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? View Available Hint(s) transforming the energy in glucose and related molecules in a chemical form that cells can use for work catabolism of sugars and related compounds producing complex molecules from chemical building blocks 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 electrons stripped from glucose in cellular respiration end up in which compound? View Available Hint(s) oxygen water ATP NADH carbon dioxide

water

The figure shows the scheme of the citric acid cycle. Starting with isocitrate, this acid undergoes 4 reactions and transforms into fumarate. During the first reaction isocitrate transforms into alpha-ketoglutarate through the regeneration of NAD with a charge of 1 plus to NADH. At the second reaction alpha-ketoglutarate transforms into succinyl CoA and NAD with a charge of 1 plus regenerates as well. The third reaction is the transformation of succinyl CoA into succinate with the synthesis of ATP from ADP and Pi. And the forth reaction ends with the transformation of succinate into fumarate through the regeneration of FAD to FADH2. the figure The citric acid cycle. Starting with one molecule of isocitrate and ending with fumarate, how many ATP molecules can be made through substrate-level phosphorylation (see the figure)? 24 11 2 1 12

1

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

2

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

2

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

60-64

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

ATP

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 synthesize ATP and pump protons into the intermembrane space. ATP synthase will synthesize ATP and pump protons into the matrix. ATP synthase will increase the rate of ATP synthesis. ATP synthase will hydrolyze 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. Plants carry out cellular respiration only in organs such as roots that cannot carry out photosynthesis. Animals carry out cellular respiration whereas plants 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.

The figure shows the electron transport chain. It consists of 4 multiprotein complexes labeled with Roman numerals. Each step of the chain is accompanied by the falling of free energy relative to O2. An electron enters the electron transport chain through the complex 1 with the release of NAD with a charge of 1 plus and then transports to FeS-protein. Also it can enter the chain through the complex 2 with the release of FAD. Entering through the complex 2 takes place a little later than through the complex 1. The electron from FAD also goes to FeS-protein. In both cases electrons from FeS-proteins go to coenzyme Q and then to complex 3 and thereafter to complex 4 through the chain of cytochromes. Which of the following is an accurate description of the events that occur along the electron transport chain depicted in the figure? Electron transfer is directly coupled to chemiosmosis. Each electron transfer between carriers results in oxidation of one carrier and reduction of another. ATP is generated directly at three points in the pathway. The potential energy of electrons increases at each step in the pathway.

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

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 oxidation of organic compounds releases less energy than the energy stored in the covalent bonds of CO2 and water. The covalent bond in O2 is unstable and easily broken by electrons from organic molecules. 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). The covalent bonds in organic molecules and molecular oxygen have more kinetic energy than the covalent bonds in water and carbon dioxide. 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).

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

FADH2

In the combined processes of glycolysis and cellular respiration, what is consumed, and what is produced? View Available Hint(s) Water is consumed, and ATP is produced. Carbon dioxide is consumed, and water is produced. ATP is consumed, and oxygen is produced. Oxygen is consumed, and glucose is produced. Glucose is consumed, and carbon dioxide is produced.

Glucose is consumed, and carbon dioxide is produced.

In the oxidation of pyruvate to acetyl CoA, one carbon atom is released as CO2. However, the oxidation of the remaining two carbon atoms—in acetate—to CO2 requires a complex, eight-step pathway—the citric acid cycle. Consider four possible explanations for why the last two carbons in acetate are converted to CO2 in a complex cyclic pathway rather than through a simple, linear reaction. Use your knowledge of the first three stages of cellular respiration to determine which explanation is correct. View Available Hint(s) More ATP is produced per CO2 released in cyclic processes than in linear processes. It is easier to remove electrons and produce CO2 from compounds with three or more carbon atoms than from a two-carbon compound such as acetyl CoA. Redox reactions that simultaneously produce CO2 and NADH occur only in cyclic processes. Cyclic processes, such as the citric acid cycle, require a different mechanism of ATP synthesis than linear processes, such as glycolysis.

It is easier to remove electrons and produce CO2 from compounds with three or more carbon atoms than from a two-carbon compound such as acetyl CoA.

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

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.

Part complete Which of the following statements about the chemiosmotic synthesis of ATP is correct? View Available Hint(s) 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? View Available Hint(s) 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 citric acid cycle produces most of the ATP that is subsequently used by the electron transport chain. The oxidation of compounds by the citric acid cycle requires molecular oxygen. 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.

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

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? lactate acetyl CoA glyceraldehyde-3-phosphate citrate oxaloacetate

acetyl CoA

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

carbohydrates only

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

glucose → NADH → electron transport chain → oxygen

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

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

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

glycolysis and fermentation

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

gylcolysis

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

inner membrane

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

lactate and NAD+

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

loses electrons and loses potential energy

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

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? oxidation of C6H12O6 and reduction of O2 reduction of CO2 and oxidation of O2 reduction of C6H12O6 and oxidation of CO2 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 FAD+ to FADH2. reduce FADH2 to FAD+. reduce NAD+ to NADH. oxidize NADH to NAD+.

oxidize NADH to NAD+.

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

pyruvate ... NADH

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

reduction of acetaldehyde to ethanol.

The primary role of oxygen in cellular respiration is to combine with acetyl CoA, forming pyruvate. donate high energy electrons to the electron transport chain. 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 _____. substrate-level phosphorylation photophosphorylation oxidative phosphorylation cellular respiration photosynthesis

substrate-level phosphorylation

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

substrate-level phosphorylation