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					Plants & Photosynthesis

Key Question (s)
Why effect does light have on photosynthesis? How will limited light in space affect

Grade Level

Module Correlation
Growing Space, Volume 3 (p. 4-5)

Carbon Dioxide

Lesson Summary
Through explanation and an equation students will learn about the process of
photosynthesis and why it is important for space exploration. An experiment will show
oxygen being produced during photosynthesis. Students will draw and write about

Learning Goals
Students will:
       1. Review the process of photosynthesis,
       2. see oxygen produced as a by-product of photosynthesis,
       3. discuss the importance of light in space, and
       4. illustrate and label the process of photosynthesis.

Science Competencies/Standards
NSES Content Standard B
     Substances react chemically in characteristic ways with other substances to form
       new substances (compounds) with different characteristic properties. In chemical
       reactions, the total mass is conserved.
    In most chemical and nuclear reactions, energy is transferred into or out of a
     system. Heat, light, mechanical motion, or electricity might all be involved in
     such transfers
NSES Content Standard C
   Populations of organisms can be categorized by the function they serve in an
     ecosystem. Plants and some micro-organisms are producers--they make their own
     food. All animals, including humans, are consumers, which obtain food by eating
     other organisms.
   For ecosystems, the major source of energy is sunlight. Energy entering
     ecosystems as sunlight is transferred by producers into chemical energy through
     photosynthesis. That energy then passes from organism to organism in food webs.

Materials Needed
   One copy per student of Photosynthesis Information-Page A
   One transparency of Photosynthesis Equation-Page B
   One transparency of Connecting Learning-Page C
   One copy per student of Photosynthesis Photo-Page D
   Large bowl filled with water
   Water plant
   Drinking glass
   Lamp
   Box of baking soda

Background Information
        Photosynthesis is the process by which plants create their own food. In this
process, plants use energy from the sun to convert carbon dioxide and water into
sugar/glucose and oxygen. This process take place in tiny chambers called chloroplasts.
Chloroplasts contain a green pigment called chlorophyll, which enables plants to absorb
the sun’s energy. Animals/humans exhale carbon dioxide gas. Plants pick up the carbon
dioxide and use it for photosynthesis. Plants release oxygen gas (as a by-product) through
tiny opening called stomata underneath their leaves.
        In order for plants to thrive, they need a high light intensity. With adequate light
plants grow more compact and exhibit increased fruit production. Sunlight is limited in
space travel. This presents an obstacle for scientists wanting to grown plants in space.
Plants are necessary for long space flight because they produce needed oxygen and food
for astronauts. In order for plants to carry on the process of photosynthesis in space, an
sufficient light source must be found.

Part One
   1. As a class read Plants Save the Day from the SAITC module. Draw student
      attention to the section describing how sunlight is needed for plant growth.
   2. Place the following chart on the board or overhead and ask students to provide
      information (given in the article) to fill in the chart.
                                  Light Effect on Plants
            Low Light Intensity                         High Light Intensity
[Plants grow tall and leggy. They seem to     [Plant growth is more compact and fruit
be reaching for a light source.]              production is increased.]

   3. Ask students, “Why do plants need high light intensity to grow?” [light is
      necessary for photosynthesis. Without photosynthesis, plants would not produce
      the food and oxygen humans need to survive.]
   4. Pass out the Photosynthesis Information-Page A and read through it as a class.
   5. Use a transparency of Photosynthesis Equation-Page B to describe how
      Photosynthesis works.
   6. Using the Photosynthesis Information-Page A and the Photosynthesis Equation-
      Page B ask students to describe the by-products of Photosynthesis. [Sugar/Food &
      Oxygen] Where does the release of oxygen occur? [Through the stomata
      underneath their leaves]

Part Two-Experiment
This experiment will allow students to watch a plant make oxygen. Since the plant is
under water, oxygen will be visible as bubbles.
   1. Fill a bowl with fresh water.
   2. Mix baking soda into the water. Show students the baking soda box and explain
       that baking soda will provide the carbon dioxide that a plant need to produce
       oxygen. Show the Photosynthesis Equation to remind students why carbon
       dioxide is needed.
   3. Place a water plant inside a drinking glass.
   4. Lower the glass sideways into the bowl of water until the glass fills with water
       and no air bubbles are left in the glass. Once all air bubbles are gone, turn the
       glass upside down in the bowl without letting in air. Let the glass rest on the
       bottom of the bowl.
   5. Aim light from a lamp toward one side of the glass.
   6. Allow an hour to pass and observe the plan in water. The majority of small
       bubbles should appear on the side closest to the light. This is oxygen produced by
       the plant. After an hour, a large bubble should be formed at the top of the glass.

   Part Three
   Connecting Learning
   Place Connecting Learning-Page C on the overhead. Discuss questions with students.
       1. What evidence do you have that photosynthesis took place?
       2. Why did most bubbles come from the side of the plant nearest the light?
          [Light is necessary for photosynthesis to occur. Where there is more light
          more oxygen will be released.]
       3. What are the by-products of photosynthesis? Why is photosynthesis essential
          for human survival? [Oxygen & Sugar/Glucose-Human survival depends on
          oxygen for breathing and glucose provides essential foods]
       4. What are the benefits of growing plants in space? [Plants will help remove the
          carbon dioxide produced by humans and increase oxygen levels. As seen in
          this experiment, the greater the light source, the more oxygen will be
       5. What factor in space limits photosynthesis? [In order for photosynthesis to
          occur, plants must have light. There is limited light availability in space.]

On Photosynthesis Photo-Page D, have students draw and explain the process of
photosynthesis. Check the labels of the photosynthesis equation placed at the top of the
page. Make sure they depict people (animals) giving off carbon dioxide and plants
giving off oxygen. Make sure there is reference to the role of a light source in

    An average tree releases enough oxygen each day to support one person. That
      person produces enough carbon dioxide to support a tree. Have students draw a
      picture representing how many trees it take to support their family.
    Have students consider the importance of light in growing plants in space. Have
      them consider solutions to the low light levels in space and write a story
      explaining how they would fix the problem.

Teacher Resources


Arizona State University-Photosynthesis

Photosynthesis, Energy, and Life – Photosynthesis Keeps Life Going

Some lesson ideas were adapted from the AIMS Middle School Life Science Curriculum