Cell Biology Chapter 14

In mitochondria, with the complete breakdown of glucose, about how many molecules of ATP can be produced for each molecule of glucose oxidized? A. 2 B. 12 C. 30 D. 50

30

Which of the following drives the production of ATP from ADP and Pi by ATP synthase? A. A proton gradient B. A Na+ gradient C. Phosphorylation

A proton gradient

In photosynthesis, what drives generation of ATP by ATP synthase? A. The transfer of high-energy electrons to ATP synthase B. The phosphorylation of ATP synthase C. The absorption of a photon of light by an adjacent chlorophyll molecule D. A proton gradient across the thylakoid membrane check my answer

A proton gradient across the thylakoid membrane

What is the main chemical energy currency in cells? A. Glucose B. NADH C. ATP D. High-energy electrons

ATP

What provides the fuel to convert CO2 into sugars in chloroplasts? A. A proton gradient across a membrane B. ATP and NADPH generated in the photosynthetic light reactions C. ATP generated in cellular respiration

ATP and NADPH generated in the photosynthetic light reactions

Membrane-associated enzyme complex that catalyzes the formation of ATP from ADP and inorganic phosphate during oxidative phosphorylation and photosynthesis

ATP synthase

What occurs when ATP synthase pumps H+ across a membrane against the electrochemical proton gradient? A. ATP synthase transports Na+ in the opposite direction across the membrane B. ATP synthase cleaves ATP to form ADP and Pi C. ATP synthase catalyzes the formation of ATP from ADP and Pi

ATP synthase cleaves ATP to form ADP and Pi

Which of the following organisms do not have mitochondria in their cells? A. Plants B. Animals C. Bacteria D. Eukaryotic microorganisms

Bacteria

Which of the following statements is true about the electron transport chain? A. Electrons start out at very high energy and lose energy at each transfer step. B. Electrons start out at very low energy and gain energy at each transfer step. C. Electrons gain and release energy as they move from one complex to another in the electron transport chain.

Electrons start out at very high energy and lose energy at each transfer step.

When a chlorophyll molecule captures light energy, what form does the energy take? A. New electrons added to the molecule B. Excited electrons C. Chemical bond formation with a molecule in the reaction center of the photosystem

Excited electrons

Why does a single molecule of NADH result in the production of more ATP molecules than a single molecule of FADH2 via oxidative phosphorylation? A. NADH donates more electrons to the chain. B. FADH2 feeds its electrons into the electron transport chain further along the chain. C. FADH2 is less likely than NADH to participate in the electron transport chain.

FADH2 feeds its electrons into the electron transport chain further along the chain

Combining CO2 and H2O to make a carbohydrate is an energetically very favorable reaction. A. True B. False

False

The storage of energy in a proton gradient derived from electron transport is a recent evolutionary development. A. True B. False

False

The first living cells on Earth-both prokaryotes and primitive eukaryotes-most likely generated ATP by what process? A. Photosynthesis B. Fermentation C. Aerobic cellular respiration

Fermentation

It is energetically favorable for protons to flow in which direction? A. From the intermembrane space to the mitochondrial matrix B. From the mitochondrial matrix to the intermembrane space

From the intermembrane space to the mitochondrial matrix

Which of the following is not a direct source of fuel for mitochondria? A. Glucose B. Pyruvate C. Fatty acids

Glucose

In the electron transport chain, what provides the main reservoir for protons that are pumped across the membrane? A. NADH B. H2O C. Glucose

H2O

What is the ratio of ATP and ADP concentrations in the cytosol of a cell? A. High ATP/ADP ratio B. High ADP/ATP ratio

High ATP/ADP ratio

In a eukaryotic cell, where are most of the proteins for the electron transport chain located? A. In the plasma membrane B. In the mitochondrial inner membrane C. In the mitochondrial outer membrane D. In the ER membrane

In the mitochondrial inner membrane

In mitochondria, what is the final electron acceptor in the electron transport chain? A. Carbon dioxide (CO2) B. Molecular oxygen (O2) C. Water (H2O) D. NADH and FADH2

Molecular oxygen (O2)

The electron transport chain accepts high-energy electrons from: A. ATP. B. pyruvate. C. NADH and FADH2. D. acetyl CoA.

NADH and FADH2

Which of the following is true? A. NADH has a strong affinity for electrons and a positive redox potential. B. NADH has a weak affinity for electrons and a negative redox potential. C. NADH has a strong affinity for electrons and a negative redox potential. D. NADH has a weak affinity for electrons and a negative redox potential.

NADH has a weak affinity for electrons and a negative redox potential.

In the electron transport chain in chloroplasts, which molecule serves as the final electron acceptor? A. NADP+ B. NADH C. H2O D. O2 check my answer

NADP+

In Earth's history, with the rise of cyanobacteria, what molecule began accumulating in the atmosphere for the first time? A. CO2 B. H2O C. O2 D. N2

O2

What electron acceptor allows an organism to completely break down organic molecules into CO2 and H2O and thereby release a large amount of energy that can be harnessed by the cell to do work? A. H2O B. O2 C. CO2 D. Pyruvate E. NAD+

O2

Stage 1 of photosynthesis is in large part equivalent to what? A. Oxidative phosphorylation B. The citric acid cycle C. Mitosis D. Glycolysis

Oxidative phosphorylation

Which of the following processes involves a membrane? A. Substrate level phosphorylation B. Oxidative phosphorylation

Oxidative phosphorylation

Which photosystem is able to boost electrons to the very high energy level needed to make NADPH from NADP+? A. Photosystem II B. Photosystem I

Photosystem I

Chlorophyll molecules absorb which color of light most strongly? A. Red B. Green C. Blue D. UV check my answer

Red

Which of the following is NOT true of mitochondria? A. They are similar in size and shape to bacteria. B. They contain their own DNA and RNA. C. They contain an outer membrane, and inner membrane, and two internal compartments. D. They are replaced by chloroplasts in plants. E. Inside a cell, they are mobile, constantly changing shape and position.

They are replaced by chloroplasts in plants.

In chloroplasts the pigment chlorophyll donates electrons to an electron transport chain in the thylakoid membrane. A. False B. True

True

Mitochondria can change their location, shape, and number in the cell to suit the needs of a cell. A. True B. False

True

The chlorophyll special pair in photosystem I actually serve as the final electron acceptor in the photosynthetic electron-transport chain. A. True B. False check my answer

True

The outer membrane of a mitochondrion is permeable to all small molecules, including small proteins. A. True B. False

True

The proton gradient can drive the active transport of metabolites into and out of the mitochondrion. A. True B. False

True

Ubiquinone has a redox potential of +30 mV, while cytochrome c has a redox potential of +230 mV. In the electron transport chain, electrons flow from: A. Ubiquinone to cytochrome c. B. Cytochrome c to ubiquinone.

Ubiquinone to cytochrome c.

Which of the following statements is NOT true of electron transfer in the electron transport chain? A. Each electron transfer is an oxidation-reduction reaction. B. When an electron carrier accepts an electron, it becomes oxidized. C. NADH has a relatively low electron affinity.

When an electron carrier accepts an electron, it becomes oxidized.

When an electron is removed from the reaction center of photosystem II, how is the missing electron then replenished? A. With an electron from a sunlight B. With an electron from a hydrogen ion C. With an electron removed from water D. With an electron removed from photosystem I

With an electron removed from water

As electrons move through the electron transport chain, they are passed from: A. a carrier molecule of lower electron affinity to a carrier molecule of higher electron affinity. B. a carrier molecule of higher electron affinity to a carrier molecule of lower electron affinity. check my answer

a carrier molecule of lower electron affinity to a carrier molecule of higher electron affinity.

In chloroplasts and photosynthetic bacteria, the part of the membrane-bound photosystem that captures energy from sunlight; contains an array of proteins that bind hundreds of chlorophyll molecules and other photosensitive pigments.

antenna complex

ATP synthase: A. can produce ATP but cannot break it down. B. can break down ATP but cannot produce it. C. can either produce or break down ATP depending on the magnitude of the electrochemical proton gradient.

can either produce or break down ATP depending on the magnitude of the electrochemical proton gradient.

Process by which green plants and other photosynthetic organisms incorporate carbon atoms from atmospheric carbon dioxide into sugars. The second stage of photosynthesis

carbon fixation

Mechanism that uses the energy stored in a transmembrane proton gradient to drive an energy-requiring process, such as the synthesis of ATP or the transport of a molecule across a membrane.

chemiosmotic coupling

Light-absorbing green pigment that plays a central part in photosynthesis.

chlorophyll

Membrane-bound, colored, heme-containing protein that transfers electrons during cellular respiration and photosynthesis.

cytochrome

Protein complex that serves as the final electron carrier in the respiratory chain; removes electrons from cytochrome c and passes them to O2 to produce H2O.

cytochrome c oxidase

In photosynthesis, the set of reactions that produce sugars from CO2; these reactions, also called carbon fixation, can occur in the absence of sunlight.

dark reactions

NADH has a strong tendency to: A. accept electrons. B. donate electrons. C. either donate or accept electrons depending on the electrochemical proton gradient.

donate electrons

The organelles that produce ATP in eukaryotic cells: A. reproduce sexually. B. harbor eukaryotic-like biosynthetic machinery for making RNA. C. have a separate set of DNA that contains many of the same genes found in the nucleus. D. evolved from bacteria engulfed by ancestral cells billions of years ago.

evolved from bacteria engulfed by ancestral cells billions of years ago.

The electron transport chain pumps protons: A. from the intermembrane space to the matrix. B. from the matrix to the intermembrane space. C. from the matrix to the cytosol.

from the matrix to the intermembrane space.

When the difference in redox potential between two pairs of molecules is highly positive, then the transfer of the electrons is: A. highly unfavorable. B. highly favorable. C. highly inefficient. D. prohibited by the laws of thermodynamics.

highly favorable.

Metal complex found in electron carriers that operate early in the electron-transport chain; has a relatively weak affinity for electrons.

iron-sulfur center

Cellular respiration: A. is more efficient at generating energy than a gasoline-powered engine. B. is less efficient at generating energy than a gasoline engine C. operates at about the same efficiency as a gasoline-powered engine D. cannot be compared to the efficiency of a gasoline engine.

is more efficient at generating energy than a gasoline-powered engine.

In photosynthesis, the set of reactions that converts the energy of sunlight into chemical energy in the form of ATP and NADPH.

light reactions

Large internal compartment within a mitochondrion.

matrix

Conversion of nitrogen gas from the atmosphere into nitrogen-containing molecules by soil bacteria and cyanobacteria.

nitrogen fixation

Large multiprotein complex containing chlorophyll that captures light energy and converts it into chemical energy; consists of a set of antenna complexes and a reaction center

photosystem

When protons move down their electrochemical gradient into the mitochondrial matrix, they: A. produce NADH. B. produce ATP. C. consume ATP. D. they move electrons through the respiratory chain.

produce ATP.

In the electron transport chain, as electrons move along a series of carriers, they release energy that is used to: A. pump protons across a membrane. B. phosphorylate ADP to form ATP. C. split water into protons and oxygen.

pump protons across a membrane.

The movement of electrons through the electron transport chain: A. consumes ATP. B. produces NADH. C. pumps protons across the inner mitochondrial membrane. D. pumps ATP across the inner mitochondrial membrane.

pumps protons across the inner mitochondrial membrane.

Small, lipid-soluble, mobile electron carrier molecule found in the respiratory and photosynthetic electron-transport chains.

quinone

In photosynthetic membranes, a protein complex that contains a specialized pair of chlorophyll molecules that performs photochemical reactions to convert the energy of photons (light) into high-energy electrons for transport down the photosynthetic electron-transport chain.

reaction center

Two molecules that can be interconverted by the gain or loss of an electron; for example, NADH and NAD+.

redox pair

A measure of the tendency of a given redox pair to donate or accept electrons.

redox potential

A reaction in which electrons are transferred from one chemical species to another. An oxidation-reduction reaction.

redox reaction

When O2 accepts electrons in the electron transport chain, O2 becomes _______. A. oxidized B. reduced

reduced

Set of proteins in the inner mitochondrial membrane that facilitates the transfer of high-energy electrons from NADH to water while pumping protons into the intermembrane space.

respiratory enzyme complex

During very active periods of photosynthesis, the glyceraldehyde-3-phosphate generated by carbon fixation in the stroma is stored as: A. ATP. B. starch. C. glycogen. D. pyruvate.

starch.

In a chloroplast, the large interior space that contains the enzymes needed to incorporate CO2 into sugars during the carbon-fixation stage of photosynthesis; equivalent to the matrix of a mitochondrion.

stroma

Photosynthesis allows plant to capture energy from sunlight to produce: A. CO2. B. sugars. C. chlorophyll. D. H2O.

sugars.

In a chloroplast, the flattened disclike sac whose membranes contain the proteins and pigments that convert light energy into chemical energy during photosynthesis.

thylakoid