ch 3 practice test

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

thermodynamic pathways

• fermentation pathways

• catabolic pathways

• anabolic pathways

• bioenergetic pathways
  

catabolic pathways

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

• The more electronegative atom is reduced, and energy is consumed.

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

• The more electronegative atom is oxidized, and energy is released.

• The more electronegative atom is oxidized, and energy is consumed.

• The more electronegative atom is reduced, and entropy decreases.
  

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

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.

• O2 is reduced and CO2 is oxidized.

• O2 is oxidized and H2O is reduced.

• C6H12O6 is reduced and CO2 is oxidized.

• CO2 is reduced and O2 is oxidized.

C₆H₁₂O₆ is oxidized and O₂ is reduced.

Which of the following statements describes NAD⁺?

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

• In the absence of NAD+, glycolysis can still function.

• NAD+ is oxidized by the action of hydrogenases.

• NAD+ has more chemical energy than NADH.

• NAD+ can donate electrons for use in oxidative phosphorylation

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

Which process in eukaryotic cells will proceed normally whether oxygen (O₂) is present or absent?

• oxidative phosphorylation

• chemiosmosis

• electron transport

• glycolysis

• the citric acid cycle
  

glycolysis

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

• 10%

• 0%

• 38%

• 2%

• 100%
  

100%

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

• CO2 and NADH

• NADH and pyruvate

• CO2 and H2O

• CO2 and pyruvate

• H2O, FADH2, and citrate
  

NADH and pyruvate

Starting with one molecule of glucose, the energy-containing products of glycolysis are

• 6 CO2, 2 ATP, and 2 pyruvate.

• 2 NAD+, 2 pyruvate, and 2 ATP.

• 2 FADH2, 2 pyruvate, and 4 ATP.

• 6 CO2, 30 ATP, and 2 pyruvate.

• 2 NADH, 2 pyruvate, and 2 ATP.
  

2 NADH, 2 pyruvate, and 2 ATP.

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

• It uses stored ATP and then forms a net increase in ATP.

• It uses glucose and generates pyruvate.

• It both splits molecules and assembles molecules.

• It shifts molecules from cytosol to mitochondrion.

• It attaches and detaches phosphate groups.
  

It uses stored ATP and then forms a net increase in ATP.

The transport of pyruvate into mitochondria depends on the proton-motive force across the inner mitochondrial membrane. How does pyruvate enter the mitochondrion?

• through a pore

• facilitated diffusion

• active transport

• through a channel

• diffusion

active transport

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

• eight

• two

• four

• ten

• six

two

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

• oxidative phosphorylation and fermentation

• fermentation and glycolysis

• glycolysis and the oxidation of pyruvate to acetyl CoA

• the citric acid cycle and oxidative phosphorylation
  

Oxidation of pyruvate to acetyl CoA and the citric acid cycle

During aerobic respiration, electrons travel downhill in which sequence?

• glucose → pyruvate → ATP → oxygen

• glucose → ATP → electron transport chain → NADH

• food → NADH → electron transport chain → oxygen

• food → citric acid cycle → ATP → NAD+

• food → glycolysis → citric acid cycle → NADH → ATP
  

food → NADH → electron transport chain → oxygen

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?

• 100/100

• 1/6

• 2/3

• 1/3

• 1/2
  

2/3

Where are the proteins of the electron transport chain located?

• cytosol

• mitochondrial inner membrane

• mitochondrial intermembrane space

• mitochondrial matrix

• mitochondrial outer membrane
  

inner mitochondrial membrane

During aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest energy level?

• ATP

• NAD+

• ADP + i

• NADH

• FADH2
  

FADH₂

Inside an active mitochondrion, most electrons follow which pathway?

• electron transport chain → citric acid cycle → ATP → oxygen

• citric acid cycle → FADH2 → electron transport chain → ATP

• pyruvate → citric acid cycle → ATP → NADH → oxygen

• glycolysis → NADH → oxidative phosphorylation → ATP → oxygen

• citric acid cycle → NADH → electron transport chain → oxygen

citric acid cycle → NADH → electron transport chain → oxygen

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

• formation of ATP.

• restoration of the Na+/K+ balance across the membrane.

• creation of a proton-motive force.

• lowering of pH in the mitochondrial matrix.

• reduction of NAD+.
  

creation of a proton-motive force.

Where is ATP synthase located in the mitochondrion?

• mitochondrial matrix

• electron transport chain

• inner membrane

• cytosol

• outer membrane
  

inner membrane

What is proton-motive force?

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

• the force that moves hydrogen to NAD+

• the force that moves hydrogen into the intermembrane space

• the force that moves hydrogen into the mitochondrion

• the force required to remove an electron from hydrogen
  

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

Which of the following occurs in the cytosol of a eukaryotic cell?

• citric acid cycle

• oxidative phosphorylation

• glycolysis and fermentation

• oxidation of pyruvate to acetyl CoA

• fermentation and chemiosmosis
  

glycolysis and fermentation

One function of both alcohol fermentation and lactic acid fermentation is to

• oxidize NADH to NAD+

• reduce FAD+ to FADH2

• reduce FADH2 to FAD+

• do none of the above

• reduce NAD+ to NADH
  

oxidize NADH to NAD⁺.

When skeletal muscle cells are oxygen-deprived, the heart still pumps. What must the heart muscle cells be able to do?

• continue aerobic metabolism when skeletal muscle cannot

• remove lactate from the blood

• transform lactate to pyruvate again

• remove oxygen from lactate

• derive sufficient energy from fermentation

continue aerobic metabolism when skeletal muscle cannot

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)?

• 2

• 12

• 11

• 24

• 1

1

For each mole of glucose (C₆H₁₂O₆) oxidized by cellular respiration, how many moles of CO₂ are released in the citric acid cycle (see Figure 9.2)?

• 6

• 12

• 3

• 2

• 4
  

4

Figure 9.3 shows the electron transport chain. Which of the following is the combination of substances that is initially added to the chain?

• oxygen and protons

• NAD+, FAD, and electrons

• NADH, FADH2, and protons

• oxygen, carbon dioxide, and water

• NADH, FADH2, and O2

NADH, FADH₂, and protons

Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?

• H2O and O2

• electrons and H+

• ADP, i, and NADP+

• CO2 and glucose

• ATP and NADPH
  

ATP and NADPH

Where does the Calvin cycle take place?

• outer membrane of the chloroplast

• interior of the thylakoid (thylakoid space)

• cytoplasm surrounding the chloroplast

• stroma of the chloroplast

• thylakoid membrane
  

stroma of the chloroplast

When oxygen is released as a result of photosynthesis, it is a direct by-product of

• chemiosmosis

• the electron transfer system of photosystem II

• reducing NADP+

• the electron transfer system of photosystem I

• splitting water molecules
  

splitting water molecules.

A plant has a unique photosynthetic pigment. The leaves of this plant appear to be reddish yellow. What wavelengths of visible light are being absorbed by this pigment?

• blue, green, and red

• blue and violet

• red and yellow

• green, blue, and yellow

• green and yellow
  

blue and violet

In the thylakoid membranes, what is the main role of the antenna pigment molecules?

• harvest photons and transfer light energy to the reaction-center chlorophyll

• transfer electrons to ferredoxin and then NADPH

• concentrate photons within the stroma

• synthesize ATP from ADP and i

• split water and release oxygen to the reaction-center chlorophyll
  

harvest photons and transfer light energy to the reaction-center chlorophyll

Which of the events listed below occurs in the light reactions of photosynthesis?

• Carbon dioxide is incorporated into PGA.

• NADPH is reduced to NADP+.

• Light is absorbed and funneled to reaction-center chlorophyll a.

• NADP is produced.

• ATP is phosphorylated to yield ADP.
  

Light is absorbed and funneled to reaction-center chlorophyll a.

What are the products of linear photophosphorylation?

• ADP and NADP

• ATP and P700

• heat and fluorescence

• P700 and P680

• ATP and NADPH
  

ATP and NADPH

In a plant cell, where are the ATP synthase complexes located?

• thylakoid membrane and inner mitochondrial membrane

• thylakoid membrane and plasma membrane

• plasma membrane only

• thylakoid membrane only

• inner mitochondrial membrane only
  

thylakoid membrane and inner mitochondrial membrane

Where are the molecules of the electron transport chain found in plant cells?

• matrix of mitochondria

• outer membrane of mitochondria

• stroma of chloroplasts

• cytoplasm

• thylakoid membranes of chloroplasts
  

thylakoid membranes of chloroplasts

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

• neither photosynthesis nor respiration

• photosynthesis only

• both photosynthesis and respiration

• respiration only

• photorespiration only
  

both photosynthesis and respiration

Reduction of NADP+ occurs during

• photosynthesis

• respiration

• both photosynthesis and respiration

• photorespiration

• neither photosynthesis nor respiration

photosynthesis

Carotenoids are often found in foods that are considered to have antioxidant properties in human nutrition. What related function do they have in plants?

• They protect against oxidative damage from excessive light energy.

• They reflect orange light and enhance red light absorption by chlorophyll.

• They shield the sensitive chromosomes of the plant from harmful ultraviolet radiation.

• They take up and remove toxins from the groundwater.

• They serve as accessory pigments to increase light absorption.
  

They protect against oxidative damage from excessive light energy.

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

• neither the light reactions nor the Calvin cycle

• the Calvin cycle alone

• both the light reactions and the Calvin cycle

• the light reactions alone

• the chloroplast, but are not part of photosynthesis
  

the light reactions alone.

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

cytosol around the chloroplast

• thylakoid space

• matrix of the mitochondria

• stroma of the chloroplast

• thylakoid membranes

stroma of the chloroplast

What is the primary function of the Calvin cycle?

• transport RuBP out of the chloroplast

• split water and release oxygen

• synthesize simple sugars from carbon dioxide

• use NADPH to release carbon dioxide

• use ATP to release carbon dioxide

synthesize simple sugars from carbon dioxide

Reactions that require CO₂ take place in

• the light reactions alone

• neither the light reactions nor the Calvin cycle

• the Calvin cycle alone

• both the light reactions and the Calvin cycle

• the chloroplast, but is not part of photosynthesis

the Calvin cycle alone.

Photorespiration occurs when rubisco reacts RuBP with

• 3-phosphoglycerate

• CO2

• glyceraldehyde 3-phosphate

• O2

• NADPH
  

O₂

Why are C₄ plants able to photosynthesize with no apparent photorespiration?

• They exclude oxygen from their tissues.

• They use PEP carboxylase to initially fix CO2.

• They are adapted to cold, wet climates.

• They conserve water more efficiently.

• They do not participate in the Calvin cycle.
  

They use PEP carboxylase to initially fix CO₂.

CAM plants keep stomata closed in daytime, thus reducing loss of water. They can do this because they

• fix CO2 into organic acids during the night.

• use the enzyme phosphofructokinase, which outcompetes rubisco for CO2.

• use photosystem I and photosystem II at night.

• fix CO2 into sugars in the bundle-sheath cells.

• fix CO2 into pyruvate in the mesophyll cells.
  

fix CO₂ into organic acids during the night.

Figure 10.1 shows the absorption spectrum for chlorophyll a and the action spectrum for photosynthesis. Why are they different?

• Green and yellow wavelengths inhibit the absorption of red and blue wavelengths.

• Aerobic bacteria take up oxygen, which changes the measurement of the rate of photosynthesis.

• Other pigments absorb light in addition to chlorophyll a.

• Oxygen given off during photosynthesis interferes with the absorption of light.

• Bright sunlight destroys photosynthetic pigments.
  

Other pigments absorb light in addition to chlorophyll a.