Quiz 7 (ch 10 +11)

Suppose the interior of the thylakoids of isolated chloroplasts were made acidic and then transferred in the dark to a pH 8 solution. What would be likely to happen?

The isolated chloroplasts will make ATP.

A mutation in yeast makes it unable to convert pyruvate to ethanol. How will this mutation affect these yeast cells?

The mutant yeast will be unable to grow anaerobically.

The pH of the inner thylakoid space and of the stroma have been measured. Which, if any, relationship would you expect to find?

The pH within the inner thylakoid space is less than that of the stroma.

What is the term for metabolic pathways that release stored energy by breaking down complex molecules?

catabolic pathways

Which of the protein complexes labeled with Roman numerals in the figure shown below will transfer electrons to O2?

complex IV

When comparing electronegativities,

correct answer all of these answers are correct oxygen is more electronegative than NADH You Answered oxygen is more electronegative than all of the components of the electron transport chain oxygen is more electronegative than FADH2

When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the direct result is the

creation of a proton-motive force.

Where does glycolysis take place in eukaryotic cells?

cytosol

It is possible to prepare vesicles from portions of the inner mitochondrial membrane. Which one of the following processes could still be carried on by this isolated inner membrane?

oxidative phosphorylation

Which of the following produces the most ATP when glucose (C6H12O6) is completely oxidized to carbon dioxide (CO2) and water?

oxidative phosphorylation (chemiosmosis)

In mechanism, photophosphorylation is most similar to

oxidative phosphorylation in cellular respiration.

In aerobic metabolism, most of the ATP produced by the oxidation of glucose to carbon dioxide is produced by

oxidative phosphorylation.

As electrons are being transported down the electron transport chain from photosystem II to photosystem I

some of the energy that is released is used to generate a proton gradient

When an electron moves from one molecule to another molecule that is more electronegative than the first molecule,

some of the potential energy that is given up by the electron is lost as heat

Where do the enzymatic reactions of the Calvin cycle take place?

stroma of the chloroplast

The ATP made during fermentation is generated by which of the following?

substrate-level phosphorylation

What is the primary function of the Calvin cycle?

synthesize simple sugars from carbon dioxide

Reactions that require CO2 take place in

the Calvin cycle alone.

Which pathways generate reduced electron carriers?

the citric acid cycle and glycolysis

When an electron moves from one molecule to another molecule that is more electronegative

the electron loses potential energy

What is proton-motive force?

the force exerted on a proton by a transmembrane proton concentration gradient

A flask containing photosynthetic green algae and a control flask containing water with no algae are both placed under a bank of lights, which are set to cycle between 12 hours of light and 12 hours of dark. The dissolved oxygen concentrations in both flasks are monitored. Predict what the relative dissolved oxygen concentrations will be in the flask with algae compared to the control flask.

The dissolved oxygen in the flask with algae will be higher in the light, but lower in the dark.

Which of the following is an important difference between aerobic and anaerobic respiration

The electron transport chain used in aerobic respiration uses O2 as the final electron acceptor whereas the electron transport chain used in anaerobic respiration uses something other than O2 as the final electron acceptor.

During photosynthesis, energy from light is first captured by

a pigment molecule in a light harvesting complex

During the electron transport phase of oxidative phosphorylation, most of the energy that is captured for later use is in the form of:

a proton gradient

Pyruvate is transported into mitochondria by

a symporter that transports pyruvate up its concentration gradient while transporting protons down their electrochemical gradient.

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?

acetyl CoA

The primary role of oxygen in cellular respiration is to

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

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

An important difference between oxidative phosphorylation and photophosphorylation is

both "b" and "c" are correct

Generation of proton gradients across membranes occurs during

both photosynthesis and respiration.

In photosynthetic cells, synthesis of ATP by the chemiosmotic mechanism occurs during

both photosynthesis and respiration.

When skeletal muscle cells continue to do work under conditions of insufficient oxygen (e.g. anaerobic exercise), they become fatigued and painful. This is now known to be caused by

buildup of lactate.

Which step in in the figure shown below is a redox reaction?

C

Which of the following statements describes the results of this reaction? C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy

C6H12O6 is oxidized and O2 is reduced.

In the reaction shown below CH4 + 2 O2 → CO2 + energy + 2 H2O

CH4 is oxidized and O2 is reduced

The "building blocks" for the production of sugar molecules that occurs during photosynthesis are

CO2 and H2O

During cellular respiration, what is the direction of energy flow?

Chemical bonds in food - to NADH - to a proton gradient - to chemical bonds in ATP

Which of the following statements describes NAD+?

NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle.

In addition to ATP, what are the end products of glycolysis?

NADH and pyruvate

Which of the following shows the molecules in the order of least to most electronegative?

NADH, e- transport chain, O2

During photosynthesis, the carbon in CO2 is reduced, helping to form sugar molecules. Which of the following statements about this process is TRUE?

NADPH donates electrons to CO2

in the reaction shown below Na and Cl → Na+ and Cl-

Na is oxidized and Cl is reduced

The absorption spectrum for chlorophyll a and the action spectrum for photosynthesis are not identical to each other. Why are they not identical?

Other pigments absorb light in addition to chlorophyll a.

Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed directly by the reactions of glycolysis?

100%

Which portion of the pathway shown in the figure below contains a phosphorylation reaction in which ATP is the phosphate source?

A

The light reactions of photosynthesis supply the Calvin cycle with

ATP and NADPH.

Drugs known as uncouplers facilitate diffusion of protons across the membrane. When such a drug is added, what will happen to ATP synthesis and oxygen consumption, if the rates of glycolysis and the citric acid cycle stay the same?

ATP synthesis will decrease; oxygen consumption will stay the same

The oxygen consumed during cellular respiration is involved directly in which process or event?

Accepting electrons at the end of the electron transport chain

Why is less ATP produced by anaerobic respiration than by aerobic respiration?

Anaerobic respiration uses a final electron acceptor that is less electronegative than O2, which is used as the final electron acceptor in aerobic respiration.

Which of the following most accurately describes what happens along the electron transport chain?

Each electron carrier alternates between being reduced and being oxidized.

When electrons move closer to a more electronegative atom, what happens?

Energy is released and the more electronegative atom is reduced

The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the

H+ concentration across the membrane holding ATP synthase.

Why is glycolysis described as having an investment phase and a payoff phase?

It first uses two stored ATP and then forms four ATP, for a net increase of two ATP.

In liver cells, the inner mitochondrial membranes are about five times the area of the outer mitochondrial membranes. What purpose must this serve?

It increases the surface for oxidative phosphorylation.

Why are carbohydrates and fats considered high-energy foods?

They have a lot of electrons associated with hydrogen.

Which of the following statements about the light reactions of photosynthesis is FALSE?

Upon absorbing the energy from a photon of light, pigment molecules in the light-harvesting complex may transfer an excited electron to a special chlorophyll a molecule in the reaction-center complex

If your muscles used alcohol fermentation instead of lactic acid fermentation, which of the following might occur?

You might become drunk during an intense workout.

The reactions of the Calvin cycle are

endergonic, and thus require a source of free energy to occur

In chemiosmotic phosphorylation, what is the most direct source of energy that is used to convert ADP + inorganic phosphate to ATP?

energy released from movement of protons through ATP synthase, down the electrochemical gradient

What does the chemiosmotic process in chloroplasts involve?

establishment of a proton gradient across the thylakoid membrane

During the light reactions of photosynthesis, electrons are transferred

from special chlorophyll a molecules to primary electron acceptors

Which metabolic pathway is common to both cellular respiration and fermentation?

glycolysis

Which of the following occur in both aerobic and anaerobic respiration?

glycolysis citric acid cycle Correct! all of these answers are correct Good work! an electron transport chain

A molecule that is phosphorylated

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

Even though plants carry on photosynthesis, plant cells still use their mitochondria for oxidation of pyruvate. When and where will this occur?

in all cells all the time

In prokaryotes, the respiratory electron transport chain is located

in the plasma membrane.

Phosphofructokinase is an allosteric enzyme that catalyzes the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate, an early step of glycolysis. In the presence of oxygen, an increase in the amount of ATP in a cell would be expected to

inhibit the enzyme and thus slow the rates of glycolysis and the citric acid cycle.

Where is ATP synthase located in the mitochondrion?

inner membrane

The direct product of the reaction catalyzed by ribulose bisphosphate carboxylase oxygenase, or "Rubisco"

is not a sugar molecule and must be reduced using electrons from NADPH to form sugar molecules

An enzyme, ribulose bisphosphate carboxylase oxygenase, or "Rubisco", attaches CO2 to a 5-carbon long sugar to form a 6-carbon long molecule, which

is unstable and splits to form two 3-carbon long molecules

The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction

loses electrons and loses energy

During aerobic respiration, H2O is formed. Where does the oxygen atom for the formation of the water come from?

molecular oxygen (O2)

In a plant leaf, the reactions that produce NADH (NADH, not NADPH) occur in

neither the light reactions nor the Calvin cycle.

Photosynthesis may be carried out

only by certain eukaryotes and certain prokaryotes

Carbon dioxide (CO2) is released during which of the following stages of cellular respiration?

oxidation of pyruvate to acetyl CoA and the citric acid cycle

When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecule becomes

oxidized.

Reduction of NADP+ occurs during

photosynthesis.

During the electron transport phase of oxidative phosphorylation, most of the energy that is captured for later use is in the form of:

proton gradient

In mitochondria, exergonic redox reactions

provide the energy that establishes the proton gradient.

What is the oxidizing agent in the following reaction? Pyruvate + NADH + H+ → Lactate + NAD+

pyruvate

Which of the following are directly associated with photosystem I?

receiving electrons from the thylakoid membrane electron transport chain

When a molecule of NAD+ (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a proton), the molecule becomes

reduced.

The energy from an excited electron can be passed from one pigment molecule to another via a process known as

resonance energy transfer

Reduction of oxygen to form water occurs during

respiration only.

Chemiosmosis

serves to generate ATP in both photosynthesis and respiration, but NADPH is produced by chemiosmosis during photosynthesis whereas NADH is used up by chemiosmosis during respiration

An electron loses potential energy when it

shifts to a more electronegative atom.

Where would you expect the genes that encode the components of the photosynthetic machinery to be located?

some in the nuclear DNA, some in the chloroplast DNA

During the light reactions of photosynthesis

the initial source of electrons is H2O and the final electron acceptor is NADP+

In mitochondria, during chemiosmosis protons move from the intermembrane space to the matrix, whereas in chloroplasts, during chemiosmosis protons move from

the inter-thylakoid space to the stroma.

The reactions that produce molecular oxygen (O2) take place in

the light reactions alone.

The direct energy source that drives ATP synthesis during respiratory oxidative phosphorylation in eukaryotic cells is

the proton-motive force across the inner mitochondrial membrane.

In photosynthesis, "resonance energy transfer" refers to

the transfer of energy from an excited electron in one pigment molecule to an electron in a different pigment molecule

What percentage of living organisms are dependent, directly or indirectly, on food molecules produced via photosynthesis?

the vast majority

The purpose of fermentation reactions is

to regenerate NAD+ so glycolysis can continue

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

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. These inside-out membrane vesicles

will become acidic inside the vesicles when NADH is added.