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BIO181 Worksheet: Photosynthesis
How do light-dependent and light-independent reactions provide food for a plant?
___________________________________________________________________________
READ THIS: Plants are the original solar panels. Through photosynthesis a plant is able to
convert electromagnetic (light) energy into chemical energy. This energy is used not only to
keep the plant alive, but also to sustain all creatures that rely on the plant for food and shelter.
Plants and photosynthetic algae are also the source of all oxygen on Earth, allowing the
inhabitants of Earth to benefit from our most plentiful renewable energy resource.
___________________________________________________________________________
Note - This image is provided as a drawing. To edit it, draw on it, add circles or labels to it, double click the image
while in Google Docs. Add in what you need to, then hit “Save and Close”.
1. Consider the organelle illustrated in Model 1.
a. What is the name of this organelle?
Chloroplast
b. Is this organelle more likely to be found in animal cells or plant cells?
Plant cells
2. The structures inside the organelle in Model 1 are called thylakoids. What compound
necessary for photosynthesis is contained in the thylakoids?
Chlorophyll
3. Consider the chemical reaction in Model 1. This represents photosynthesis.
a. What substances are the reactants in photosynthesis? Include the name and
chemical formula of each substance in your answer.
Carbon dioxide (CO2), water (H2O)
b. Where in the organelle are these molecules stored before they are used in
photosynthesis? stroma
c. Is photosynthesis an endergonic or exergonic reaction? Support your answer
, 3. Consider the chemical reaction in Model 1. This represents photosynthesis.
a. What substances are the reactants in photosynthesis? Include the name and
chemical formula of each substance in your answer.
Carbon dioxide (CO2), water (H2O)
b. Where in the organelle are these molecules stored before they are used in
photosynthesis? stroma
c. Is photosynthesis an endergonic or exergonic reaction? Support your answer
with evidence from Model 1.
Endergonic because the product (G3P) contains more energy than the reaction.
d. What is the energy source for photosynthesis?
Sunlight (electromagnetic energy)
4. Photosynthesis occurs in two parts—the light-dependent reactions and the light-
independent reactions.
a. What is another name for the light-independent reactions?
the Calvin cycle
b. In what part of the chloroplast do the light-dependent reactions occur?
thylakoid membrane
c. In what part of the chloroplast do the light-independent reactions occur?
stroma
5. Considering your answers to Question 4, what compound is best able to absorb the light
energy from the Sun and convert it into chemical energy?
The thylakoid, and the chlorophyll in the thylakoid, would best be able to absorb the light energy from the sun
and convert it into chemical energy because the thylakoid specializes in light-dependent reactions
6. What substances are produced during photosynthesis? Include the name and chemical
formula of each substance in your answer.
Oxygen (O2), Water (H2O), Glucose (C6H12O6)
7. Why is it necessary to have six CO2 entering the chloroplast?
It is necessary to have six CO2 entering the chloroplast because they will interact with the 12 hydrogen atoms
and six of the oxygen atoms from the 12 H2O molecules to form one glucose molecule. A glucose molecule has a
chemical structure of C6H12O6, so six carbon atoms, and thus six CO2 molecules, are needed.
BIO181 Worksheet: Photosynthesis
How do light-dependent and light-independent reactions provide food for a plant?
___________________________________________________________________________
READ THIS: Plants are the original solar panels. Through photosynthesis a plant is able to
convert electromagnetic (light) energy into chemical energy. This energy is used not only to
keep the plant alive, but also to sustain all creatures that rely on the plant for food and shelter.
Plants and photosynthetic algae are also the source of all oxygen on Earth, allowing the
inhabitants of Earth to benefit from our most plentiful renewable energy resource.
___________________________________________________________________________
Note - This image is provided as a drawing. To edit it, draw on it, add circles or labels to it, double click the image
while in Google Docs. Add in what you need to, then hit “Save and Close”.
1. Consider the organelle illustrated in Model 1.
a. What is the name of this organelle?
Chloroplast
b. Is this organelle more likely to be found in animal cells or plant cells?
Plant cells
2. The structures inside the organelle in Model 1 are called thylakoids. What compound
necessary for photosynthesis is contained in the thylakoids?
Chlorophyll
3. Consider the chemical reaction in Model 1. This represents photosynthesis.
a. What substances are the reactants in photosynthesis? Include the name and
chemical formula of each substance in your answer.
Carbon dioxide (CO2), water (H2O)
b. Where in the organelle are these molecules stored before they are used in
photosynthesis? stroma
c. Is photosynthesis an endergonic or exergonic reaction? Support your answer
, 3. Consider the chemical reaction in Model 1. This represents photosynthesis.
a. What substances are the reactants in photosynthesis? Include the name and
chemical formula of each substance in your answer.
Carbon dioxide (CO2), water (H2O)
b. Where in the organelle are these molecules stored before they are used in
photosynthesis? stroma
c. Is photosynthesis an endergonic or exergonic reaction? Support your answer
with evidence from Model 1.
Endergonic because the product (G3P) contains more energy than the reaction.
d. What is the energy source for photosynthesis?
Sunlight (electromagnetic energy)
4. Photosynthesis occurs in two parts—the light-dependent reactions and the light-
independent reactions.
a. What is another name for the light-independent reactions?
the Calvin cycle
b. In what part of the chloroplast do the light-dependent reactions occur?
thylakoid membrane
c. In what part of the chloroplast do the light-independent reactions occur?
stroma
5. Considering your answers to Question 4, what compound is best able to absorb the light
energy from the Sun and convert it into chemical energy?
The thylakoid, and the chlorophyll in the thylakoid, would best be able to absorb the light energy from the sun
and convert it into chemical energy because the thylakoid specializes in light-dependent reactions
6. What substances are produced during photosynthesis? Include the name and chemical
formula of each substance in your answer.
Oxygen (O2), Water (H2O), Glucose (C6H12O6)
7. Why is it necessary to have six CO2 entering the chloroplast?
It is necessary to have six CO2 entering the chloroplast because they will interact with the 12 hydrogen atoms
and six of the oxygen atoms from the 12 H2O molecules to form one glucose molecule. A glucose molecule has a
chemical structure of C6H12O6, so six carbon atoms, and thus six CO2 molecules, are needed.
