Question 1

The electrons "stored" in the structure of NADPH contain much higher energy than the electrons of water.These NADPH electrons are raised in energy by the transfer of energy from photosynthetic pigments.Why does it take two photochemical events to accomplish this?

Accepted Answer

A single red photon does not c...

Question 2

High intensity light has a negative effect on photosynthesis;in fact,too much light can diminish photosynthetic output.This phenomenon is known as _______.

Accepted Answer

A)  photousurpation
B)  photodiminishment
C)  photoinhibition
D)  photosynthetic diminishment
E)  disinhibition

Question 3

Why is CO2 split off of the C4 carriers once they get into the bundle sheath cells?

Accepted Answer

A)  so that the CO2 can be used by Rubisco to initiate the Calvin cycle
B)  so that the CO2 can be used by PEP carboxylase to initiate the Calvin cycle
C)  so that the CO2 can be used by Rubisco to initiate the Hatch-Slack pathway
D)  so that the CO2 can be used by PEP carboxylase to initiate the Hatch-Slack pathway
E)  so that the O2 can be used by Rubisco to initiate the Calvin cycle

Question 4

Which three organelles in a leaf are found closely associated with each other and cooperate with each other in such a way that products of one organelle serve as substrates in another?

Accepted Answer

A)  peroxisomes,lysosomes,mitochondria
B)  chloroplasts,mitochondria,lysosomes
C)  chloroplasts,nuclei,mitochondria
D)  mitochondria,chloroplasts,peroxisomes
E)  chloroplasts,nuclei,peroxisomes

Question 5

What is the difference between the way C3 and C4 plants fix CO2 from the atmosphere?

Accepted Answer

A)  C3 plants fix CO2 and conduct the light-dependent reactions in the same cells;C4 plants conduct these activities in different cells.
B)  C4 plants fix CO2 and conduct the light-dependent reactions in the same cells;C3 plants conduct these activities in different cells.
C)  C3 plants fix CO2 and conduct the light-dependent reactions at the same time of day;C4 plants conduct these activities at different times of the day.
D)  C4 plants fix CO2 and conduct the light-dependent reactions at the same time of day;C3 plants conduct these activities at different times of the day.
E)  C3 plants fix CO2 and conduct the light-independent reactions in the same cells;C4 plants conduct these activities in different cells.

Question 6

How do C4 and CAM plants overcome the negative effects of photorespiration?

Accepted Answer

A)  They destroy O2.
B)  They chemically alter O2 before it gets to the enzyme.
C)  They employ mechanisms that increase the CO2/O2 ratio to which Rubisco molecules are exposed.
D)  They chemically alter CO2.
E)  They destroy CO2.

Question 7

The chloroplast internal membrane is organized into flattened membranous sacs called _________;they,in turn,are arranged in orderly stacks called _______ that contain energy-transducing machinery

Accepted Answer

A)  thylakoids,grana
B)  grana,thylakoids
C)  thylakoids,stroma thylakoids
D)  thylakoids,grana thylakoids
E)  grana thylakoids,thylakoids

Question 8

The earliest photosynthetic organisms on Earth probably used what substance as an electron source for photosynthesis?

Accepted Answer

A)  water
B)  hydrogen sulfide
C)  hydrogen sulfite
D)  carbon dioxide
E)  carbohydrates

Question 9

If Calvin cycle enzymes are treated with a reagent that stabilizes their disulfide linkages,what effect might the treatment have on the enzymes?

Accepted Answer

A)  It might competitively inhibit them.
B)  It might noncompetitively inhibit them.
C)  It might split them in two pieces.
D)  It might activate them.
E)  It might deactivate them.

Question 10

How does high intensity light supposedly damage PSII?

Accepted Answer

A)  If overexcited,PSII becomes highly acidic.
B)  If overexcited,PSII becomes highly basic.
C)  If overexcited,PSII can damage PSI.
D)  If overexcited,PSII can form toxic oxygen radicals.
E)  If overexcited,PSII dissociates.

Question 11

You are observing an organism.It appears to extract energy stored in inorganic molecules like ammonia,nitrites and hydrogen sulfide;it uses carbon dioxide as its primary carbon source.What kind of organism is it?

Accepted Answer

It is a ch...

Question 12

Why might Rubisco have evolved with an inability to distinguish between CO2 and O2?

Accepted Answer

A)  Rubisco may have evolved at a time when atmospheric O2 levels were virtually nonexistent.
B)  Rubisco may have evolved at a time when atmospheric CO2 levels were virtually nonexistent.
C)  Rubisco evolved when atmospheric O2 levels were high.
D)  Rubisco possesses four subunits.
E)  Rubisco denatures due to photorespiration.

Question 13

As energy passes through a photosynthetic unit,it is transferred to a pigment molecule that absorbs at a(n) ______ wavelength,so energy is _____ and the nature of future transfers becomes restricted.

Accepted Answer

A)  equal or longer,lost
B)  equal or longer,gained
C)  equal or shorter,gained
D)  equal or shorter,lost
E)  equal,the same

Question 14

How does paraquat destroy human tissue?

Accepted Answer

A)  It competes with ferredoxin for electrons from the PSI reaction center.
B)  It interferes with PSI function.
C)  Electrons attached to paraquat are used to reduce nitrogen,generating highly reactive nitrogen radicals.
D)  It leads to the production of substances that damage and kill the tissue.
E)  It generates oxygen radicals using electrons diverted from complex I of the respiratory chain.

Question 15

What is a reason for having mobile electron carriers in the thylakoid membranes? Does the movement require energy or is it passive?

Accepted Answer

The PSI and PSII photosystems ...

Question 16

What part of PSII appears to suffer most of the damage from high intensity light?

Accepted Answer

A)  the reaction center photopigment
B)  the D1 polypeptide of PSII
C)  the electrons
D)  NADPH
E)  both the D1 polypeptide of PSII and NADPH

Question 17

In chloroplasts,a proton gradient is established with a higher concentration of protons found in the ______ and a lower concentration in the ______.

Accepted Answer

A)  thylakoid lumen,intermembrane space
B)  intermembrane space,thylakoid lumen
C)  thylakoid lumen,stroma
D)  stroma,thylakoid lumen
E)  intermembrane space,matrix

Question 18

The initial product of carbon fixation contains ____ carbons,but it breaks down into two compounds containing _____ carbons.

Accepted Answer

A)  8,4
B)  6,3
C)  6,6
D)  10,5
E)  12,6

Question 19

What enzyme is responsible for fixing CO2 out of the atmosphere in C4 plants?

Accepted Answer

A)  PEP decarboxylase
B)  ATP synthase
C)  PEP carboxylase
D)  Rubisco
E)  ribulose bisphosphate carboxylase

Question 20

What determines the direction of the Rubisco-catalyzed reaction?

Accepted Answer

A)  the concentration of O2 alone
B)  the concentration of CO2 alone
C)  the CO2/O2 ratio available to the enzyme
D)  Rubisco itself
E)  cofactors for Rubisco

Exam 6: Photosynthesis and the Chloroplast

What determines the direction of the Rubisco-catalyzed reaction?

Correct AnswerverifiedShow Answer

The initial product of carbon fixation contains ____ carbons,but it breaks down into two compounds containing _____ carbons.

Correct AnswerverifiedShow Answer

The electrons "stored" in the structure of NADPH contain much higher energy than the electrons of water.These NADPH electrons are raised in energy by the transfer of energy from photosynthetic pigments.Why does it take two photochemical events to accomplish this?

Correct AnswerverifiedA single red photon does not c...View AnswerShow Answer

High intensity light has a negative effect on photosynthesis;in fact,too much light can diminish photosynthetic output.This phenomenon is known as _______.

Correct AnswerverifiedShow Answer

Which three organelles in a leaf are found closely associated with each other and cooperate with each other in such a way that products of one organelle serve as substrates in another?

Correct AnswerverifiedShow Answer

In chloroplasts,a proton gradient is established with a higher concentration of protons found in the ______ and a lower concentration in the ______.

Correct AnswerverifiedShow Answer

You are observing an organism.It appears to extract energy stored in inorganic molecules like ammonia,nitrites and hydrogen sulfide;it uses carbon dioxide as its primary carbon source.What kind of organism is it?

Correct AnswerverifiedIt is a ch...View AnswerShow Answer

How does high intensity light supposedly damage PSII?

Correct AnswerverifiedShow Answer

What enzyme is responsible for fixing CO2 out of the atmosphere in C4 plants?

Correct AnswerverifiedShow Answer

How do C4 and CAM plants overcome the negative effects of photorespiration?

Correct AnswerverifiedShow Answer

Why might Rubisco have evolved with an inability to distinguish between CO2 and O2?

Correct AnswerverifiedShow Answer

What is the difference between the way C3 and C4 plants fix CO2 from the atmosphere?

Correct AnswerverifiedShow Answer

What part of PSII appears to suffer most of the damage from high intensity light?

Correct AnswerverifiedShow Answer

Why is CO2 split off of the C4 carriers once they get into the bundle sheath cells?

Correct AnswerverifiedShow Answer

As energy passes through a photosynthetic unit,it is transferred to a pigment molecule that absorbs at a(n) ______ wavelength,so energy is _____ and the nature of future transfers becomes restricted.

Correct AnswerverifiedShow Answer

The chloroplast internal membrane is organized into flattened membranous sacs called _________;they,in turn,are arranged in orderly stacks called _______ that contain energy-transducing machinery

Correct AnswerverifiedShow Answer

If Calvin cycle enzymes are treated with a reagent that stabilizes their disulfide linkages,what effect might the treatment have on the enzymes?

Correct AnswerverifiedShow Answer

How does paraquat destroy human tissue?

Correct AnswerverifiedShow Answer

The earliest photosynthetic organisms on Earth probably used what substance as an electron source for photosynthesis?

Correct AnswerverifiedShow Answer

What is a reason for having mobile electron carriers in the thylakoid membranes? Does the movement require energy or is it passive?

Correct AnswerverifiedThe PSI and PSII photosystems ...View AnswerShow Answer

Correct Answer
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The initial product of carbon fixation contains carbons,but it breaks down into two compounds containing _ carbons.

Correct Answer
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Correct Answer
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A single red photon does not c...
View Answer

Correct Answer
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Correct Answer
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In chloroplasts,a proton gradient is established with a higher concentration of protons found in the and a lower concentration in the .

Correct Answer
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Correct Answer
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It is a ch...
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Correct Answer
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What enzyme is responsible for fixing CO₂ out of the atmosphere in C₄ plants?

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How do C₄ and CAM plants overcome the negative effects of photorespiration?

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Why might Rubisco have evolved with an inability to distinguish between CO₂ and O₂?

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What is the difference between the way C₃ and C₄ plants fix CO₂ from the atmosphere?

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Correct Answer
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Why is CO₂ split off of the C₄ carriers once they get into the bundle sheath cells?

Correct Answer
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As energy passes through a photosynthetic unit,it is transferred to a pigment molecule that absorbs at a(n) __ wavelength,so energy is _ and the nature of future transfers becomes restricted.

Correct Answer
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The chloroplast internal membrane is organized into flattened membranous sacs called ___;they,in turn,are arranged in orderly stacks called _ that contain energy-transducing machinery

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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The PSI and PSII photosystems ...
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