Photosynthesis Questionnaire
The paragraph below describes the events of the light dependent reactions. Fill in the blanks in the
paragraph.
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Photosynthesis occurs in the part of the cell called the ___1___. Inside this
part of the cell are flattened sacs called ___2___. Within the membranes of
these flattened sacs the ___3___ reactions will occur. Large stacks of these
sacs are called ___4___. Surrounding these flattened sacs is a dense solution
called the ___5___. In this solution, the ___6___reactions will occur. The
purpose of photosynthesis is to take the reactants ___7___, ___8___, and
___9___ and produce the products of ___10___ and ___11___. A ___12___is
a collection of chlorophyll molecules that serve as the light collecting unit of
photosynthesis. These chlorophyll molecules are found embedded in the
___13___membranes .
Let’s start with photosystem II. Chlorophyll molecules in photosystem II
absorb the ___14___from the sun. The ___15___ of these chlorophyll
molecules become very excited. The ___16___are boosted to a higher energy
level and are passed to an ___17___. The electrons that were lost from these
molecules of ___18___ must now be replaced. Molecules of ___19___ are
split and the ___20___ from this are used to replaced the electrons that were
lost. ___21___ from the water is considered a waste product and is ___22___.
The high energy electrons now move down the ___23___ as they are passed
from ___24___ to ___25___. As the electrons are passed down this electron
transport chain, protein molecules use the energy from these electrons to create
___26___.
The electrons from photosystem II arrive at ___27___. The ___28___
molecules of photosystem I absorb ___29___ from the sun and use it to reenergize the electrons. These electrons are passed down a second ___30___ to
the electron acceptor called ___31___. NADP+ joins with these electrons and
one H+ to form ___32___.
ATP is actually formed when ___33___ ions flow through ___34___ from an
area of ___35___ concentration inside the thylakoid to an area of ___36___
concentration outside the thylakoid. As hydrogen passes through the enzyme
___37___ the protein spins, creating energy. This energy is used to convert
___38___ to ___39___ Hydrogen ions must now be pumped back inside the
___40___ from the ___41___. These will be pumped against the concentration
gradient and will require ___42___. The energy for this process comes from
___43___.
Was any glucose produced in these light dependent reactions? ___44___. The
purpose of the light dependent reactions is to produce ___45___ and
___46___so that they can be used in the ___47___.
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48.
What is the relationship between sunlight and chlorophyll? Why are both of these needed for
photosynthesis?
49.
What two substances are produced by the light dependent reactions that are required for the light
independent reactions?
50.
What is the role of plant pigments in the light dependent reactions?
51.
What is the function of ATP synthase? How does it work?
52.
How does light enter the light dependent reactions?
53.
What happens to the electrons that are lost by photosystem II?
What happens to the electrons that are lost by photosystem I?
How are electrons that are lost by the chlorophyll molecules replaced?
54.
Name three substances that are produced when water molecules are split during the light dependent
reactions.
55.
The air contains oxygen that we need to breathe. What is the source of this oxygen?
56.
What is the relationship between these two terms: grana / stroma
57.
What happens to the components of water molecules that are split during the light reactions of
photosynthesis?
58.
How is ATP actually produced in photosynthesis?
2
59.
_____________________ This adds a phosphate group to ADP to form ATP.
60.
_____________________ This is a cluster of pigment molecules embedded in the thylakoid membrane.
61. ______________________ This is produced in the light dependent reactions, but is released and does not
participate any further in photosynthesis.
62. ______________________ Flattened sacs containing chlorophyll.
63.
______________________ The dense solution found inside the chloroplast.
64.
65.
______________________ The molecule that serves as the carrier of high energy electrons between the
thylakoids and the stroma.
______________________ What substances are required for the light dependent reactions?
66.
______________________ What substances are required for the light independent reactions?
_________67
Where would one find photosystems and electron transport chains? (1) along the cristae
membrane (2) embedded in the outer membrane of the chloroplast (3) embedded in the
inner membrane of the chloroplast (4) embedded in the thylakoid membranes (5) in the
stroma of the chloroplast.
_________68
What is produced in the light dependent reactions that is not needed for the light independent
reactions?
(1) water (2) carbon dioxide (3) NADPH (4) ATP (5) oxygen
__________69
Which one of the following is true of both photosystem I and photosystem II? (1) They both
absorb light energy which is used to energize electrons in chlorophyll-a molecules. (2) Each
receives electrons from the other photosystem. (3) Both photosystems produce NADPH.
(4) Both photosystems split molecules of water. (5) Both photosystems produce glucose
molecules.
__________70
Which of the following is the most immediate role of water in the light dependent reactions?
(1) It is split so that it can donate electrons to NADP+ to form NADPH. (2) It is split and
then can donate electrons to photosystem II. (3) Water accepts electrons from the electron
transport chain. (4) The hydrogen from water is used to accept electrons from ADP.
__________71
Which of the following is not produced during the light dependent reactions?
(1) NADPH (2) oxygen (3) glucose molecules (4) ATP (5) hydrogen ions
__________72
Which one of the following occurs at the end of the electron transport chain of photosystem I?
(1) Electrons combine with NADP+ to form NADPH (2) ATP is produced (3) The
electrons from photosystem II are replaced. (4) Water molecules are split. (5) Glucose is
produced.
3
True/False
_________73 High energy electrons move along the thylakoid membrane from photosystem I to
photosystem II.
_________74 The oxygen that is released into the atmosphere comes from the splitting of a carbon dioxide
molecule.
_________75 Photosynthesis is the process of converting light energy into the chemical energy of a molecule
of glucose.
_________76 ATP molecules are produced during the light independent reactions of photosynthesis.
_________77 Carbon dioxide is produced during photosynthesis.
_________78 The light dependent reactions takes place along the thylakoid membranes of the mitochondria.
_________79 Chlorophyll molecules are found embedded along the thylakoid membrane.
_________80 In the light dependent reactions, electrons pass from water to chlorophyll to electron transport
chains, ultimately producing NADPH.
_________81 There are two photosystems but only one electron transport chain.
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Answers:
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chloroplast
thylakoids
light dependent reactions
grana
stroma
light independent reactions
carbon dioxide
water
light energy
glucose
oxygen
photosystem
thylakoid
energy
electrons
electrons
electron transport chain
chlorophyll
water
electrons
oxygen
released to the atmosphere
electron transport chain
photosystem II
photosystem I
ATP
photosystem I
chlorophyll
energy
electron transport chain
NADP+
NADPH
H+
ATP synthase
high
low
ATP synthase
ADP
ATP
thylakoid
stroma
energy
the electron transport chain
no
ATP
NADPH
light independent reactions
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48.
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57.
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73.
74.
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80.
81.
The chlorophyll is able to absorb all the wavelengths of light (except green) from the visible spectrum.
This energizes the electrons of chlorophyll. The chlorophyll is needed to absorb the energy of the sun,
and the sun is needed to energize the electrons found in chlorophyll molecules.
ATP and NADPH
Pigments absorb the visible spectrum of light causing electrons in pigments to become energized.
ATP synthase is a protein embedded in the thylakoid membrane that converts ADP to ATP. Hydrogen
ions flow through ATP synthase from an area of high concentration inside the thylakoid to an area of low
concentration in the stroma. As the hydrogen ions flow through ATP synthase, it turns a rotor. This
generates the energy used to bind the third phosphate onto ADP to form ATP.
The light energy is absorbed by the molecules of chlorophyll.
Electrons from photosystem II are passed down the electron transport chain to photosystem I.
Electrons from photosystem I are passed down an electron transport chain and are accepted by NADP+ to
form NADPH.
The replacement electrons come from the splitting of water molecules.
ATP, NADPH, oxygen
The oxygen is released to the atmosphere when water molecules are split.
Grana: the site of the light dependent reactions
Stroma: the site of the light independent reactions
The oxygen is released to the atmosphere. The hydrogen atoms are used to produce ATP and NADPH.
ATP synthase is a protein embedded in the thylakoid membrane that converts ADP to ATP. Hydrogen
ions flow through ATP synthase from an area of high concentration inside the thylakoid to an area of low
concentration in the stroma. As the hydrogen ions flow through ATP synthase, it turns a rotor. This
generates the energy used to bind the third phosphate onto ADP to form ATP.
ATP synthase
photosystem
oxygen
thylakoids
stroma
NADP+
water, sunlight, chlorophyll
carbon dioxide, RuBP, ATP, NADPH
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5
1
2
3
1
False
False
True
False
False
False
True
True
False
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