Download HS Solar Energy: Photosynthesis

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H.S. Solar Energy: Photosynthesis
Created by:
Learning Cycle 5E Lesson
Based upon and modified from Roger Bybee* (1990)
*Bybee, R & Landes, N. (1990). Science for life and living: An elementary school science program from
Biological Sciences Curriculum Study (BSCS). American Biology Teacher. 52 (2). 92-98.
Photosynthesis
Next Generation Science Standards (NGSS)
Earth and Space Science:
 HS-ESS2-4. Use a model to describe how variations in the flow of energy into
and out of Earth’s systems result in changes in climate.
 HS-ESS3-5. Analyze geoscience data and the results from global climate
models to make an evidence-based forecast of the current rate of global or
regional climate change and associated future impacts to Earth systems.
 HS-ESS3-6. Use a computational representation to illustrate the
relationships among Earth systems and how those relationships are being
modified due to human activity.
Physical Science:
 HS-PS3-1 Create a computational model to calculate the change in the
energy of one component in a system when the change in energy of the other
component(s) and energy flows in and out of the system are known.
Life Science:
 HS-LS2-5. Develop a model to illustrate the role of photosynthesis and
cellular respiration in the cycling of carbon among the biosphere, atmosphere,
hydrosphere, and geosphere.
 HS-LS1-5. Use a model to illustrate how photosynthesis transforms light
energy into stored chemical energy.
Background Knowledge
Teacher:
The sun is an enormous nuclear power source (see The Sun and its Core lesson) through complex reactions, it transforms hydrogen into helium, releasing light and
heat. Because of these reactions, every square meter of our planet's surface gets
about 342 Watts of energy from the sun every year (that’s a lot of energy!).
According to NASA, this is about 1.7 x 1017 Watts total, or as much as 1.7 billion
large power plants could generate. When this energy reaches the Earth, it provides
power for a variety of reactions, cycles and systems. The main way that solar energy
is captured and stored on Earth is through the complex chemical process known as
photosynthesis.
Through this lesson students will develop a model to illustrate the role of
photosynthesis and cellular respiration in the cycling of carbon among the
biosphere, atmosphere, hydrosphere, and geosphere. Photosynthesis and cellular
respiration are important components of the carbon cycle, in which carbon is
exchanged among the biosphere, atmosphere, oceans, and geosphere through
chemical, physical, geological and biological processes.
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The cycling of matter and the flow of energy within ecosystems occur through
interactions among different organisms and between organisms and the physical
environment. All living systems need matter and energy. Matter fuels the energyreleasing chemical reactions that provide energy for life functions and provides the
material for growth and repair of tissue. Energy from light is needed for plants
because the chemical reaction that produces plant matter from air and water
requires an energy input to occur. Animals acquire matter from food, that is, from
plants or other animals. The chemical elements that make up the molecules of
organisms pass through food webs and the environment and are combined and
recombined in different ways. At each level in a food web, some matter provides
energy for life functions, some is stored in newly made structures, and much is
discarded to the surrounding environment. Only a small fraction of the matter
consumed at one level is captured by the next level up. As matter cycles and energy
flows through living systems and between living systems and the physical
environment, matter and energy are conserved in each change.
The carbon cycle provides an example of matter cycling and energy flow in
ecosystems. Photosynthesis, digestion of plant matter, respiration, and
decomposition are important components of the carbon cycle, in which carbon is
exchanged between the biosphere, atmosphere, oceans, and geosphere through
chemical, physical, geological, and biological processes.
Photosynthesis and cellular respiration (including anaerobic processes) provide
most of the energy for life processes. Plants or algae form the lowest level of the food
web. At each link upward in a food web, only a small fraction of the matter
consumed at the lower level is transferred upward, to produce growth and release
energy in cellular respiration at the higher level. Given this inefficiency, there are
generally fewer organisms at higher levels of a food web, and there is a limit to the
number of organisms that an ecosystem can sustain.
The chemical elements that make up the molecules of organisms pass through food
webs and into and out of the atmosphere and soil and are combined and recombined
in different ways. At each link in an ecosystem, matter and energy are conserved;
some matter reacts to release energy for life functions, some matter is stored in
newly made structures, and much is discarded. Competition among species is
ultimately competition for the matter and energy needed for life.
Photosynthesis is responsible for absorbing atmospheric carbon dioxide and
producing oxygen that is released into the atmosphere. Carbon dioxide (CO2) is the
primary greenhouse gas emitted through human activities. In 2012, CO2 accounted
for about 82% of all U.S. greenhouse gas emissions from human activities. Carbon
dioxide is naturally present in the atmosphere as part of the Earth's carbon cycle
(the natural circulation of carbon among the atmosphere, oceans, soil, plants, and
animals). Human activities are altering the carbon cycle—both by adding more CO2
to the atmosphere and by influencing the ability of natural sinks, like forests, to
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remove CO2 from the atmosphere. While CO2 emissions come from a variety of
natural sources, human-related emissions are responsible for the increase that has
occurred in the atmosphere since the industrial revolution.
Earth’s temperature depends on the balance between energy entering and leaving
the planet’s system. When incoming energy from the sun is absorbed by the Earth
system, Earth warms. When the sun’s energy is reflected back into space, Earth
avoids warming. When energy is released back into space, Earth cools. Greenhouse
gases like CO2 prevent the sun’s energy from reflecting back into space causing
what many scientists believe to be global warming.
Student:
A. Prior Standards:
a.
b.
c.
d.
e.
MS. Structure and Properties of Matter
MS.Energy
MS.Matter and Energy in Organisms and Ecosystems
MS.History of Earth
MS.Earth's Systems
B. Life Experience: Students will have experience touching, seeing, perhaps
planting or chopping down trees. Students may also have experience
planting gardens. Students will have experience learning or hearing about
global warming and/or greenhouse gases in conversations, in the media,
and in school.
Time
90 minutes
Materials List
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Student Guides
Photosynthesis and Carbon Cycle PPT
Oven bag (2 for each group of 3-4 students)
1 plant per group
2 thermometers per group
1 box of baking soda
1 bottle of vinegar
1 lamp per group (or sunlight + lamp)
1 empty plastic (preferably reused and washed from the plastic recycle bin)
per group
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4 large alligator clips per group
Safety Procedures
The lamp might get very hot depending on the type used. Have students also be
cautious when working with liquids and powders. Make sure the floors are clean
and that any spills are wiped dry to make sure students don’t slip. Balloons might
pop during this exercise so warn students who might be startled easily.
Engagement
After reviewing objectives on Slide 2, proceed through Slides 3-5. Asking students
questions about photosynthesis and its importance. Ask students what the world
would look like without the sun. Carbon dioxide and oxygen are key terms that
should come up during this conversation.
Exploration
The goal in this lab is to create 2 mini-micro-climates. One with a plant and one
without. We will be adding carbon dioxide to each of these different climates to see
what differences occur because of the plant (if any). If possible, this lab might work
better outside using light from the sun and a lamp (serving as more of a heat source
if it’s cold outside). You can also modify this lesson to not use the plant and to
simply measure the temperature difference of one oven bag with carbon dioxide and
one without carbon dioxide. Show Slide 6.
Set up
Step 1: Prepare your oven bags by placing thermometers in each bag and a plant
only one of the bags.
Step 2: Set up a station where your lamp can easily shine on the bag. Be careful not
to burn yourself on the lamp!
Make Carbon Dioxide
Step 3: Take the balloon with the baking soda and place the opening of it carefully
over the mouth of the bottle. DO NOT let the baking soda fall into the vinegar until
it is securely over the mouth of the bottle.
Step 4: Lift the balloon so that the baking soda falls into the bottle with vinegar.
You just created carbon dioxide in the balloon!
Step 3: Carefully take the balloon off the bottle without letting the gas escape. Close
the balloon with a clothespin or alligator clip.
Step 5: Place the balloon in the bag with the plant and securely close the oven bag
with a clothes pin or alligator clip (see diagram on next page).
Step 6: Remove the seal from the balloon from outside of the bag so that all the gas
escapes.
Step 7: Repeat steps 1-3 then place that balloon in the bag that has no plant. Repeat
steps 4-5 to release the gas into the oven bag.
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Step 8: Place both oven bags under the lamp (just try to get each one equal amount
of light.
Step 9: Students will record any temperature changes using their student guides.
Step 10: Watch the video on Slide 7 then have students review what they’ve learned
by asking questions (see Explanation).
Step 11: Have students complete their Student Guides.
Explanation
1.
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5.
How does photosynthesis affect our environment?
How does photosynthesis affect carbon dioxide and oxygen?
How do high levels of carbon dioxide affect our environment?
Relate the oven bag experiment to the greenhouse effect.
What would have happened to the solar energy that was trapped by the
carbon dioxide?
Scientific Vocabulary:
 Photosynthesis: Photosynthesis is a process used by plants and other
organisms to convert light energy, normally from the sun, into chemical
energy that can be later released to fuel the organisms' activities. This
chemical energy is stored in carbohydrate molecules, such as sugars, which
are synthesized from carbon dioxide and water – hence the name
photosynthesis, from the Greek, phōs, "light", and synthesis, "putting
together". In most cases, oxygen is also released as a waste product. Most
plants, algae, and cyanobacteria perform photosynthesis, and such organisms
are called photoautotrophs. Photosynthesis maintains atmospheric oxygen
levels and supplies all of the organic compounds and most of the energy
necessary for life on Earth.
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Cellular Respiration: Cellular respiration is the process of oxidizing food molecules,
like glucose, to carbon dioxide and water. Photosynthesis and respiration are
reactions that complement each other in the environment. They are in reality the
same reactions but occurring in reverse. They work well since living organisms
supply plants with carbon dioxide which undergoes photosynthesis and produces
glucose and these plants and bacteria give out oxygen which all living organisms
need for respiration.
Carbon dioxide: A naturally occurring chemical compound composed of two oxygen
atoms each covalently double bonded to a single carbon atom. Some carbon dioxide is
produced by plants during respiration. Carbon dioxide is produced by combustion of
coal or hydrocarbons, the fermentation of sugars in beer and winemaking and by
respiration of all living organisms. It is exhaled in the breath of humans and other
land animals. The environmental effects of carbon dioxide are of significant interest.
Carbon dioxide is an important greenhouse gas, absorbing heat radiation from
Earth's surface which otherwise would leave the atmosphere. Burning of carbonbased fuels since the industrial revolution has rapidly increased concentrations of
atmospheric carbon dioxide, increasing the rate of global warming and causing
anthropogenic climate change. It is also a major source of ocean acidification since it
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dissolves in water to form carbonic acid, which is a weak acid as its ionization in
water is incomplete.
Deforestation: The removal of a forest or stand of trees where the land is thereafter
converted to a non-forest use. Examples of deforestation include conversion of
forestland to farms, ranches, or urban use.
Afforestation: The establishment of a forest or stand of trees in an area where there
was no forest.
Greenhouse gas: A greenhouse gas (sometimes abbreviated GHG) is a gas in an
atmosphere that absorbs and emits radiation within the thermal infrared range.
This process is the fundamental cause of the greenhouse effect. The primary
greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide,
methane, nitrous oxide, and ozone.
Elaboration
Have students visit Climate Interactive’s website to run simulations based on
carbon dioxide emissions, afforestation and deforestation. Prior to this lesson the
teacher should explore this simulation program to explain the different parts and
definitions such as afforestation and deforestation. There is also an instructional
video on this website to help the teacher and the students navigate the system.
http://www.climateinteractive.org/tools/c-learn/simulation/
The goal is for students to run a simulation that keeps temperature change below 2
degrees and CO2 concentrations below 450 parts per million. Have students either
print their main control panel or write down the criteria they used in their
simulation.
Ask them if they believe their simulation is realistic and what kind of changes
would have to take place for the simulation to become a reality.
Evaluation
Formative: Qualitative Data
Classroom participation assessed informally based on contribution to discussions,
group work, and completion of Student Guide. Ask students questions about their
own carbon footprint. Ask students how many trees or plants are in their own
neighborhood. Ask students if they’ve ever planted a tree. Ask students if they
believe a forest being planted in the Nevada desert would cool down temperatures
in that area.
Summative: Quantitative Data
Use the Student Guide and the results from the Climate Interactive Simulation for
evaluation.
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Rubric
Understanding of photosynthesis:
Understanding of photosynthesis’
role in removing carbon dioxide
from the atmosphere:
Understanding of carbon dioxide
and its environmental impacts:
Understanding impact of
afforestation on global warming:
15
25
25
15
Clean-up
Have students return all materials after the lab is completed to the teacher. Ensure
that areas are clean as there can be some baking soda and vinegar messes!
Closure
Review Slide 9 to go over restated objectives for the lesson as a group.
Adaptations for ESL, Special Ed, or G.T.
Not applicable.
Management Strategy
In this unit students will be involved in a collaborative learning exercise as well as
a computer lab exercise. The teacher should define respect and consistently
reinforce respectful and collaborative behaviors. It will also be important to
emphasize clean and orderly set up for the lab since there are some materials that
can spill and/or explode (like the balloon). Students may get very excited and
sociable during this time. Keep students on task by visiting groups, reminding them
of time limits, and referring back to the Explanation and Evaluation questions.
This project will require the teacher to design a classroom environment conducive to
these activities and to possibly reserve a computer room.
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