Module 7; Cellular Respiration

Figure 9.2 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 Figure 9.2)? 1 2 11 12 24

1

Figure 9.2 The citric acid cycle. For each molecule of glucose that is metabolized by glycolysis and the citric acid cycle (see Figure 9.2), what is the total number of NADH + FADH2 molecules produced? 4 5 6 10 12

12

What fraction of the carbon dioxide exhaled by animals is generated by the reactions of the citric acid cycle, if glucose is the sole energy source? 1/6 1/3 1/2 2/3 100/100

2/3

Which portion of the pathway in Figure 9.1 contains a phosphorylation reaction in which ATP is the phosphate source? A B C D E

A

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

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

Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." These little vesicles that result can still transfer electrons from NADH to oxygen and synthesize ATP. If the membranes are agitated further, however, the ability to synthesize ATP is lost. After the further agitation of the membrane vesicles, what must be lost from the membrane? the ability of NADH to transfer electrons to the first acceptor in the electron transport chain the prosthetic groups like heme from the transport system cytochromes ATP synthase, in whole or in part the contact required between inner and outer membrane surfaces

ATP synthase, in whole or in part

Brown fat cells produce a protein called thermogenin in their mitochondrial inner membrane. Thermogenin is a channel for facilitated transport of protons across the membrane. What will occur in the brown fat cells when they produce thermogenin? ATP synthesis and heat generation will both increase. ATP synthesis will increase, and heat generation will decrease. ATP synthesis will decrease, and heat generation will increase. ATP synthesis and heat generation will both decrease. ATP synthesis and heat generation will stay the same.

ATP synthesis will decrease, and heat generation will increase.

In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of ATP, CO2, and ethanol (ethyl alcohol). ATP, CO2, and lactate. ATP, NADH, and pyruvate. ATP, pyruvate, and oxygen. ATP, pyruvate, and acetyl CoA.

ATP, CO2, and ethanol (ethyl alcohol).

Figure 9.1 illustrates some of the steps (reactions) of glycolysis in their proper sequence. Each step is lettered. Use these letters to answer the questions. In which step in Figure 9.1 is an inorganic phosphate added to the reactant? A B C D E

C

Which of the following most accurately describes what is happening along the electron transport chain in Figure 9.3? Chemiosmosis is coupled with electron transfer. Each electron carrier alternates between being reduced and being oxidized. ATP is generated at each step. Energy of the electrons increases at each step. Molecules in the chain give up some of their potential energy.

Each electron carrier alternates between being reduced and being oxidized.

Why does the oxidation of organic compounds by molecular oxygen to produce CO2 and water release free energy? The covalent bonds in organic molecules and molecular oxygen have more kinetic energy than the covalent bonds in water and carbon dioxide. 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 oxidation of organic compounds can be used to make ATP. The electrons have a higher potential energy when associated with water and CO2 than they do in organic compounds. 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).

In liver cells, the inner mitochondrial membranes are about five times the area of the outer mitochondrial membranes. What purpose must this serve? It allows for an increased rate of glycolysis. It allows for an increased rate of the citric acid cycle. It increases the surface for oxidative phosphorylation. It increases the surface for substrate-level phosphorylation. It allows the liver cell to have fewer mitochondria.

It increases the surface for oxidative phosphorylation.

Phosphofructokinase is an important control enzyme in the regulation of cellular respiration. Which of the following statements correctly describes phosphofructokinase activity? It is inhibited by AMP. It is activated by ATP. It is activated by citrate, an intermediate of the citric acid cycle. It catalyzes the conversion of fructose 1,6-bisphosphate to fructose 6-phosphate, an early step of glycolysis. It is an allosteric enzyme.

It is an allosteric enzyme.

When electrons move closer to a more electronegative atom, what happens? The more electronegative atom is reduced, and energy is released. The more electronegative atom is reduced, and energy is consumed. The more electronegative atom is oxidized, and energy is consumed. The more electronegative atom is oxidized, and energy is released. The more electronegative atom is reduced, and entropy decreases.

The more electronegative atom is reduced, and energy is released.

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

a proton gradient across a membrane.

The oxygen consumed during cellular respiration is involved directly in which process or event? glycolysis accepting electrons at the end of the electron transport chain the citric acid cycle the oxidation of pyruvate to acetyl CoA the phosphorylation of ADP to form ATP

accepting electrons at the end of the electron transport chain

Which of the following intermediary metabolites enters the citric acid cycle and is formed, in part, by the removal of a carbon (CO2) from one molecule of pyruvate? lactate glyceraldehydes-3-phosphate oxaloacetate acetyl CoA citrate

acetyl CoA

The transport of pyruvate into mitochondria depends on the proton-motive force across the inner mitochondrial membrane. How does pyruvate enter the mitochondrion? active transport diffusion facilitated diffusion through a channel through a pore

active transport

Which kind of metabolic poison would most directly interfere with glycolysis? an agent that reacts with oxygen and depletes its concentration in the cell an agent that binds to pyruvate and inactivates it an agent that closely mimics the structure of glucose but is not metabolized an agent that reacts with NADH and oxidizes it to NAD+ an agent that blocks the passage of electrons along the electron transport chain

an agent that closely mimics the structure of glucose but is not metabolized

What is the purpose of beta oxidation in respiration? oxidation of glucose oxidation of pyruvate feedback regulation control of ATP accumulation breakdown of fatty acids

breakdown of fatty acids

When skeletal muscle cells undergo anaerobic respiration, they become fatigued and painful. This is now known to be caused by buildup of pyruvate. buildup of lactate. increase in sodium ions. increase in potassium ions. increase in ethanol.

buildup of lactate.

Where does glycolysis take place in eukaryotic cells? mitochondrial matrix mitochondrial outer membrane mitochondrial inner membrane mitochondrial intermembrane space cytosol

cytosol

Yeast cells that have defective mitochondria incapable of respiration will be able to grow by catabolizing which of the following carbon sources for energy? glucose proteins fatty acids glucose, proteins, and fatty acids Such yeast cells will not be capable of catabolizing any food molecules, and will therefore die

glucose

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

glycolysis

A molecule that is phosphorylated has been reduced as a result of a redox reaction involving the loss of an inorganic phosphate. has a decreased chemical reactivity; it is less likely to provide energy for cellular work. has been oxidized as a result of a redox reaction involving the gain of an inorganic phosphate. has an increased chemical potential energy; it is primed to do cellular work. has less energy than before its phosphorylation and therefore less energy for cellular work.

has an increased chemical potential energy; it is primed to do cellular work.

Energy released by the electron transport chain is used to pump H+ into which location in eukaryotic cells? cytosol mitochondrial outer membrane mitochondrial inner membrane mitochondrial intermembrane space mitochondrial matrix

mitochondrial intermembrane space

During cellular respiration, acetyl CoA accumulates in which location? cytosol mitochondrial outer membrane mitochondrial inner membrane mitochondrial intermembrane space mitochondrial matrix

mitochondrial matrix

During aerobic respiration, H2O is formed. Where does the oxygen atom for the formation of the water come from? carbon dioxide (CO2) glucose (C6H12O6) molecular oxygen (O2) pyruvate (C3H3O3-) lactate (C3H5O3-)

molecular oxygen (O2)

Which of the following produces the most ATP when glucose (C6H12O6) is completely oxidized to carbon dioxide (CO2) and water? glycolysis fermentation oxidation of pyruvate to acetyl CoA citric acid cycle oxidative phosphorylation (chemiosmosis)

oxidative phosphorylation (chemiosmosis)

The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is oxygen. water. NAD+. pyruvate. ADP.

oxygen.

When a molecule of NAD+ (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a proton), the molecule becomes dehydrogenated. oxidized. reduced. redoxed. hydrolyzed.

reduced.

An electron loses potential energy when it shifts to a less electronegative atom. shifts to a more electronegative atom. increases its kinetic energy. increases its activity as an oxidizing agent. moves further away from the nucleus of the atom.

shifts to a more electronegative atom.

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

substrate-level phosphorylation

Most CO2 from catabolism is released during glycolysis. the citric acid cycle. lactate fermentation. electron transport. oxidative phosphorylation

the citric acid cycle.

In vertebrate animals, brown fat tissue's color is due to abundant blood vessels and capillaries. White fat tissue, on the other hand, is specialized for fat storage and contains relatively few blood vessels or capillaries. Brown fat cells have a specialized protein that dissipates the proton-motive force across the mitochondrial membranes. Which of the following might be the function of the brown fat tissue? to increase the rate of oxidative phosphorylation from its few mitochondria to allow the animals to regulate their metabolic rate when it is especially hot to increase the production of ATP to allow other membranes of the cell to perform mitochondrial functions to regulate temperature by converting most of the energy from NADH oxidation to heat

to regulate temperature by converting most of the energy from NADH oxidation to heat

How many carbon atoms are fed into the citric acid cycle as a result of the oxidation of one molecule of pyruvate? two four six eight ten

two