Lesson 2
Biology
Engage: Energy Conversions
A solar panel is used to charge a cell phone battery. For each stage identified below, fill
in the boxes with the type of energy involved in each conversion.
1. Light energy is collected by the solar panels and stored in the battery.
+
2. The battery is used to power the phone.
+
3. The power from the phone is used to light up the display on the phone.
+
4. Describe the energy conversions that occur during photosynthesis.
© 2013 Region 4 Education Service Center
STAAR™ Achievement Series for Science
Lesson 2
Biology
Explore: Modeling the Photosynthesis and Cellular Respiration
Equations
Instructions: Place the terms oxygen (O2), glucose (C6H12O6), carbon dioxide (CO2),
and water (H2O) in the correct boxes below. In your science notebook, write the
photosynthesis equation using the molecules of each substance. The substances that go
into the plant should be written on the reactants side of the equation below. The
substances that are produced by the plant should be written on the products side.
Photosynthesis Equation
Sunlight
________ + _________
Reactants
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________ + _________
Products
STAAR™ Achievement Series for Science
Lesson 2
Biology
Explore: Modeling the Photosynthesis and Cellular Respiration
Equations
---------------------------------------------------------------------------------------------------------------------Cut apart the molecules below.
C
H
H
O
O
O
C
H
H
O
O
O
C
H
H
O
O
O
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C
H
H
O
O
O
C
H
H
O
O
O
C
H
H
O
O
O
© 2013 Region 4 Education Service Center
Lesson 2
Biology
Explore: Modeling the Photosynthesis and Cellular Respiration
Equations
Part I: Photosynthesis
1. Use scissors to cut out the carbon, hydrogen, and oxygen atoms.
2. You were provided with the exact number of carbon, hydrogen, and oxygen atoms
that you will need to complete photosynthesis.
3. Use the atoms to create the reactants of photosynthesis. You will need to make as
many water molecules and carbon dioxide molecules as you can.
4. On the reactants side of the equation, record the number of carbon dioxide and
water molecules using coefficients.
5. The reactants enter the chloroplast during photosynthesis. Solar energy is used to
break the water and carbon dioxide molecules apart. Through a series of
reactions, the atoms are recombined to form the products of photosynthesis.
6. Use the same atoms to form the products.
7. In your science notebook, record the number of glucose and oxygen molecules on
the products side of the equation.
Photosynthesis Equation
Sunlight
________ + _________
________ + _________
Reactants
Products
Part II: Cellular Respiration
1. Copy the cellular respiration equation into your science notebook.
2. Use the same atoms you used during photosynthesis to model the process of
cellular respiration.
3. Use the atoms to create the reactants of cellular respiration (glucose and oxygen).
4. Record the number of glucose and oxygen molecules on the reactants side of the
equation in your science notebook.
5. The reactants enter the mitochondria during cellular respiration. Through a series
of reactions, the products of cellular respiration are produced.
6. Use the same atoms to form the products of photosynthesis. Produce as many
water molecules and carbon dioxide molecules as possible.
7. Use the number of water molecules and carbon dioxide molecules to fill in the
products side of the cellular respiration equation.
8. Save your molecules. You will use them during the Explain activity.
Cellular Respiration Equation
_______ + _______
Reactants
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______ + ______ + 36 ATP
Products
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Lesson 2
Biology
Explain 1: Overview of Photosynthesis
Instructions: As you read the passage below, work as a team to move the
molecules through the chloroplast. Make sure to use all of the molecules.
In photosynthetic organisms, photosynthesis occurs inside chloroplasts. During
photosynthesis, water and carbon dioxide are used to produce glucose and oxygen. As
this process occurs, radiant energy is converted to chemical energy. There are many
reactions that occur in photosynthesis. The main reactions are summarized below.
Step 1: Light-Dependent Reactions
Inside the thylakoids of chloroplasts, solar energy begins a series of chemical
reactions that causes water molecules inside the chloroplast to split apart.
Oxygen is released as a byproduct and exits the leaf. Through these chemical
reactions, the radiant energy from sunlight is transferred to two high-energy
compounds—ATP and NADPH. NADPH is formed when hydrogen ions and two
high-energy electrons are carried by special transport molecules called NADP+.
ATP and H+ ions are used as energy sources to continue the chemical reactions
necessary for the plant to make carbohydrates. This process is known as a
light-dependent reaction because it requires light.
Stroma
Step 2: Light-Independent Reactions
The second series of chemical reactions take place within the stroma of the
chloroplast. Through chemical reactions, molecules of carbon dioxide are
split apart, rearranged, and bonded with hydrogen ions to produce highenergy sugars. This process is known as a light-independent reaction
because it does not require light.
© 2013 Region 4 Education Service Center
STAAR™ Achievement Series for Science
Lesson 2
Biology
Explain 1: Overview of Photosynthesis
---------------------------------------------------------------------------------------------------------------------Cut apart the boxes below.
6 O2 molecules
6 molecules H2O
C6H12O6
6 molecules CO2
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© 2013 Region 4 Education Service Center
© 2013 Region 4 Education Service Center
NADP + ADP + P
NADPH + ATP
Stroma—empty
space between
thylakoids
Explain 1: Model of a Chloroplast
Lesson 2
Biology
STAAR™ Achievement Series for Science
Lesson 2
Biology
Explain 2: Energy Conversions Analogy
Instructions:
1. Determine the energy conversions that occur in the airplane.
2. Determine the energy conversions that occur in the cell.
Chemical
Energy (Fuel)
H H
C
H CH
H
H
C H
H
C H
H C
H C H
H C H
H H
Gasoline
Waste Products
Energy Conversion
Heat
energy
H
H
O
Water
Combustion
+
+
Kinetic energy
(movement)
C
O
O
O
O
Oxygen
Energy Conversions in an Airplane
Heat
energy
Carbon Dioxide
Energy for cellular
activities
Cellular
Respiration
O
Water
ATP
+
Glucose
+
O
O
H
H
C
O
Energy Conversions in a Cell
O
Carbon Dioxide
Oxygen
© 2013 Region 4 Education Service Center
STAAR™ Achievement Series for Science
Lesson 2
Biology
Elaborate: Organism 1 Card
Instructions: Read the description of the organism below. In your science notebook,
record your answers to the questions.
Scientists in Texas believe that they have discovered a new organism. The organism is
unicellular, golden in color, and contains many brown accessory pigments in its
chloroplasts. The organism is found in ponds and lakes. The organism possesses two
flagella, both attached near the same end of the cell.
1. Predict how the organism above obtains energy. Do you think it carries out
photosynthesis or cellular respiration?
2. Explain the cellular energy conversions you think would occur.
3. What evidence would you expect to find to prove that photosynthesis or cellular
respiration occurred?
Experiment 1
Description: Scientists conducted the following experiment on Organism 1. Read the
description of the experiment and examine the data provided. In your science notebook,
explain whether the evidence in the experiment matches your prediction.
Procedure Followed:
1. Add 1–2 drops of bromothymol blue to 15 mL of water in a 25 mL graduated
cylinder. Gently blow into the tube using a straw until the liquid changes to a
greenish yellow color. Label the test tube “A.”
2. Add 1–2 drops of bromothymol blue to 15 mL of water in a 25 mL graduated
cylinder. Gently blow into the tube using a straw until the liquid changes to a
greenish yellow color. Label the test tube “B.” Add the new organism to the test
tube.
3. Record your initial observations in Table 1.1.
4. Recheck the test tubes in 24 hours. Record your observations in Table 1.1.
Test Tube A
Test Tube B
Table 1.1
Initial Observations
yellow liquid
yellow liquid
Final Observations
yellow liquid
blue liquid
Note: Bromothymol blue is an indicator of pH. The indicator is blue in the
presence of a base. The solution will change to yellow in the presence of an acid.
Carbon dioxide causes a solution to become more acidic. Alternatively, if carbon
dioxide is removed from a solution, the solution becomes more basic.
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© 2013 Region 4 Education Service Center
Lesson 2
Biology
Elaborate: Organism 2 Card
Instructions: Read the description of the organism below. In your science notebook,
record your answers to the questions
In 2010, a new organism, Spongiforma squarepantsii, was discovered in Malaysia. The
mushroom has many characteristics that reminded scientists of a sponge character
seen on TV. Organisms in the Kingdom Fungi share the characteristics of being
eukaryotic, multicellular heterotrophs with cell walls. This organism, as with many
mushrooms, is a decomposer.
1. Do you think the organism obtains its energy from photosynthesis or cellular
respiration?
2. Explain the cellular energy conversions you think would occur.
3. What evidence would you expect to find to prove that photosynthesis or cellular
respiration occurred?
Experiment 2
Description: Scientists conducted the following experiment on Organism 2. Read the
description of the experiment and examine the data provided. Explain in your scientific
notebook whether the evidence in the experiment matches your prediction.
Procedure Followed: The newly discovered mushroom was placed in a sealed
container monitored by two gas sensors. The sensors monitored the amount of carbon
dioxide gas and oxygen gas surrounding the mushroom. The results are summarized in
Table 1.2.
Organism
Spongiforma
squarepantsii
Table 1.2
Oxygen
(ppt/s)
–0.0025
(O2 was consumed.)
Carbon Dioxide
(ppt/s)
0.00075
(CO2 was produced.)
Note: Ppt/s indicates parts per trillion per second
© 2013 Region 4 Education Service Center
STAAR™ Achievement Series for Science
Lesson 2
Biology
Name: ________________________________________
Date: __________
Evaluate: Cellular Energy Conversions
The plant shown in the resealable plastic bag is producing gas bubbles. If the gas bubbles
are carbon dioxide, it can be inferred that —
1
2
A
solar energy is converted to chemical energy
B
chemical energy is converted to chemical energy
C
chemical energy is converted to kinetic energy
D
solar energy is converted to radiant energy
Evidence for photosynthesis includes —
F
bromothymol blue turning yellow in the presence of carbon dioxide
G
a negative test for glucose
H
a carbon dioxide probe detecting an increase in CO2 during cellular respiration
J
bromothymol blue remaining blue in the presence of oxygen
© 2013 Region 4 Education Service Center
STAAR™ Achievement Series for Science
Lesson 2
Biology
3
4
Which of the following would best represent the energy conversions of cellular respiration
when glucose is broken down and energy is stored in ATP?
A
Radiant energy  chemical energy
B
Chemical energy  chemical energy
C
Solar energy  kinetic energy
D
Mechanical energy  chemical energy
In cellular respiration, glucose and oxygen are converted to —
F
oxygen, water, and light
G
lactic acid and ATP
H
carbon dioxide and starch
J
carbon dioxide, water, and ATP
STAAR™ Achievement Series for Science
© 2013 Region 4 Education Service Center
Lesson 2
Biology
5. Read the experiment summarized below. Explain why the covered portion of the
leaf tested negative for starch. Plants make starch using glucose.
The following experiment was conducted to investigate photosynthesis:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Place a plant in the dark for 48 hours.
Cover a portion of a leaf with tape and place the plant in sunlight. (Half of
the leaf will be covered with tape, the other half will be left alone.)
After 24 hours of sunlight exposure, remove the leaf with tape from the
plant.
Remove the tape from the leaf.
Place the leaf in boiling water for 1 minute. Boiling the leaf kills the leaf.
Remove the leaf from the water.
Place the leaf in a test tube of ethyl alcohol.
Place the test tube in a hot-water bath. Allow the leaf to remain in the
ethyl alcohol for approximately 2 minutes. Ethyl alcohol breaks down the
chlorophyll in the leaf, removing the green color.
Use forceps to rinse the leaf.
Dry the leaf and lay the leaf out flat.
Place the leaf in a Petri dish and cover the leaf with iodine. Iodine is an
indicator that turns blue-black in the presence of starch.
Data Table for Starch Test
Observations
Results of Starch Test
Covered portion of leaf
Exposed portion of leaf
The tested area of the
leaf remained the original
brown color of the iodine.
The tested area of the
leaf turned blue-black.
© 2013 Region 4 Education Service Center
negative for starch
positive for starch
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