Lesson Plan

Photosynthesis and Cell Respiration

Objectives

In this lesson, students compare the basic energy transfer in photosynthesis and cell respiration, with a focus on the role of ATP. Students will:

  • compare energy transfer during photosynthesis and cell respiration.
  • describe the roles of chloroplasts and mitochondria in energy transfer.
  • describe the role of ATP in photosynthesis and cell respiration.

Essential Questions

Vocabulary

  • Adenosine triphosphate (ATP): Chemical compound that living things use to store and release energy.
  • Aerobic: A process that requires oxygen.
  • Anaerobic: A process that does not require oxygen.
  • Cell Respiration: A process that releases energy in cells by breaking down glucose and other food molecules in the presence of oxygen. Aerobic, or oxidative, respiration requires oxygen; anaerobic respiration does not require oxygen.
  • Chlorophyll: Green pigment inside chloroplasts that captures light energy.
  • Chloroplast: Organelle in cells of plants, and some algae and some microorganisms that captures sunlight energy and converts it into chemical energy.
  • Glycolysis: A series of chemical reactions that takes place in the cell’s cytoplasm by which glucose is converted into pyruvate without oxygen.
  • Grana: Stacks of thylakoids inside chloroplasts.
  • Nicotinamide adenine dinucleotide phosphate (NADP+): Carrier molecule found in plants that transfers high-energy electrons.
  • Photosynthesis: The process of plants, some algae, and some microorganisms that uses light energy to convert water and carbon dioxide into oxygen and high-energy carbohydrates such as sugars, starches, proteins, and lipids.
  • Pyruvate: The compound glucose is broken down into during the process of glycolysis.
  • Stomata: Openings in the underside of leaves that allow carbon dioxide and oxygen to enter and leave the leaves.
  • Stroma: The area in the chloroplast outside the thylakoid membranes.
  • Thylakoid: Membrane-bound structure inside chloroplasts where photosynthesis takes place.

Duration

120–160 minutes/3–4 class periods

Prerequisite Skills

Prerequisite Skills haven't been entered into the lesson plan.

Materials

  • house plant, such as Coleus or Elodea
  • fish from aquarium or picture of a fish
  • aluminum foil
  • scissors
  • tape
  • microscope with projector (optional)
  • prepared slide of leaf cells with visible chloroplasts (optional)
  • Internal Structure of a Chloroplast (S-B-7-2_Internal Structure.doc); use with a document camera or make an overhead transparency
  • Reactions of Photosynthesis (S-B-7-2_Reactions of Photosynthesis.doc); use a document camera or make an overhead transparency
  • Photosynthesis (The Light and Calvin Reactions) (S-B-7-2_Light and Calvin Reactions and KEY.doc)
  • optional demonstration

o   sprig of Elodea plant (can be obtained at aquarium stores)

o   beaker or large clear plastic cup

o   sodium bicarbonate solution

o   large test tube

o   goggles

o   containers with lids (test tubes or sealable plastic bags will work)

o   Bromothymol blue solution, 4%

o   pond or aquarium water

o   Elodea or other aquarium plant (can be ordered through a biological supply company or obtained at local aquarium store)

o   small aquatic snails, guppies, or daphnia (can be ordered through a biological supply company or obtained at local aquarium store)

Related Unit and Lesson Plans

Related Materials & Resources

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  • house plant, such as Coleus or Elodea
  • fish from aquarium or picture of a fish
  • aluminum foil
  • scissors
  • tape
  • microscope with projector (optional)
  • prepared slide of leaf cells with visible chloroplasts (optional)
  • Internal Structure of a Chloroplast (S-B-7-2_Internal Structure.doc); use with a document camera or make an overhead transparency
  • Reactions of Photosynthesis (S-B-7-2_Reactions of Photosynthesis.doc); use a document camera or make an overhead transparency
  • Photosynthesis (The Light and Calvin Reactions) (S-B-7-2_Light and Calvin Reactions and KEY.doc)
  • optional demonstration

o   sprig of Elodea plant (can be obtained at aquarium stores)

o   beaker or large clear plastic cup

o   sodium bicarbonate solution

o   large test tube

o   goggles

o   containers with lids (test tubes or sealable plastic bags will work)

o   Bromothymol blue solution, 4%

o   pond or aquarium water

o   Elodea or other aquarium plant (can be ordered through a biological supply company or obtained at local aquarium store)

o   small aquatic snails, guppies, or daphnia (can be ordered through a biological supply company or obtained at local aquarium store)

Formative Assessment

  • View
    • Have students recall what they know about the structure and function of the mitochondria and chloroplasts from Lessons 1 and 2:

    o   On Day 1, assess students’ background knowledge during the introduction discussion. Collect and assess the Photosynthesis (The Light and Calvin Reactions) chart and the exit tickets.

    o   On Day 2, observe students as they take notes on cell respiration. Collect and assess the Cell Respiration Worksheet.

    o   On Days 3–4, monitor students during the lab activity. Check their hypotheses to see if students understand the concept of using bromothymol blue solution as an indicator of photosynthesis and respiration. Collect and assess the lab worksheet. Assess students’ understanding of the overall concept of energy transformation during the concluding class discussion.

Suggested Instructional Supports

  • View
    Scaffolding, Active Engagement, Explicit Instruction
    W: This is a lesson on the complementary processes of photosynthesis and cell respiration. The focus is on the overall energy transfer in each process, as well as the roles of the chloroplast, mitochondria, and ATP.
    H: The first part of the lesson begins with students observing a house plant that has been in the sun for a few days, with aluminum foil covering parts of the plant. Students discuss why plants need sunlight, and then compare the basic needs of plants and animals.
    E: The lesson includes explicit instruction, a demonstration, guided and independent practice, and a lab activity on the relationship between photosynthesis and cell respiration.
    R: Students are given opportunities to review the concepts in graphic organizers, worksheets, an Exit Ticket, class discussions, and in the follow-up questions to the lab.
    E: Students express their understanding in class discussions, in writing on worksheets, and hands-on during the lab experiment.
    T: This lesson can be tailored by providing an overall explanation of the energy transformations of photosynthesis and cell respiration at the beginning and end of the lesson. Several suggestions are provided in the Extension section.
    O: This lesson builds on what students learned about the functions of the mitochondria and the chloroplast in Lesson 1. Photosynthesis and cell respiration are presented separately, and then the lab requires students to synthesize the concepts from both processes.

Instructional Procedures

  • View

    Day 1: Photosynthesis

    To prepare, cut out shapes of aluminum foil and tape them to various part of a house plant’s leaves. Place the plant in the sun for several days.

    To introduce the lesson, ask “What do plants and animals need to survive?” Show students a plant such as Coleus or Elodea and a picture of a fish (or a real fish). Make a chart on board, such as the one below, and have students help you fill it in.

     

    Plants

    Both

    Animals

    Sunlight

    Carbon dioxide

    Animals

    Water

    Nutrients

    Shelter (suitable environmental conditions)

    Oxygen

    Plants

     

    Ask, “In a small fish bowl that contains a fish and a plant, what will happen over time?”

    Students should mention the exchange of oxygen and carbon dioxide between the fish and the plant. Tell students that plants and animals on Earth are interdependent.

    Tell students that this lesson is all about the energy exchange between plants and animals in the processes of photosynthesis and cell respiration, and that the lesson will focus on photosynthesis. Explain that the simplest way to explain photosynthesis is that it is the process of making energy from light. Have students point out where on the house plant photosynthesis takes place. (in the chloroplasts inside leaf cells)

    Have students recall what they know about the structure and function of chloroplasts from Lesson 1. Show students the images in Internal Structure of a Chloroplast (S-B-7-2_Internal Structure.doc) and point out the stroma, thylakoids, and grana. If you have a microscope with a projector, this is a good time to show students actual magnified leaf cells and point out the chloroplasts.

    Optional Demonstration

    Fill a beaker or plastic cup about halfway with sodium bicarbonate solution (a source of carbon dioxide). Place a sprig of an Elodea plant into a large test tube with the cut stem at the bottom. Fill the test tube with sodium bicarbonate solution. Holding your thumb over the mouth of the test tube, turn it upside down and lower it carefully into the beaker. Make sure there is no air trapped in the tube. Have students observe the setup carefully and describe what they see. Place the cup in bright sunlight. Leave it for at least 20 minutes, and then show it to students again. They should see bubbles of gas around the Elodea leaves. Remind students that photosynthesis produces sugars and oxygen, and because sugars are not gases, this must be oxygen gas. Oxygen is a waste product of photosynthesis because it is released from the plant into the environment.

    Guided Practice

    Hand out copies of Photosynthesis (The Light and Calvin Reactions) (S-B-7-2_Light and Calvin Reactions and KEY.doc). Write the equation for photosynthesis on the board and have students write it on the worksheet, and have them write the equation in sentence form.

    light

    6CO2 + 6H2O     C6H12O6 + 6O2

    Tell students that scientists describe photosynthesis in two parts: the light-dependent reaction and the light-independent reaction, or Calvin cycle. Show students the diagram of the reactions using Reactions of Photosynthesis (S-B-7-2_Reactions of Photosynthesis.doc). Describe the light-dependent reaction and the Calvin cycle using the diagram, and have students take notes in the chart on the worksheet. Be sure to explain the roles of ATP (chemical compound that living things use to store and release energy) and NADP+ (carrier molecule that transfers high-energy electrons from chlorophyll to chemical reactions in other parts of the cell) in the reactions.

    Exit Ticket: Describe the role of ATP in the process of photosynthesis.

    Day 2: Cell Respiration

    Mini-Lesson: Have students take notes as you explain cell respiration. Explain that overall, photosynthesis and cell respiration are opposite processes. Remind students that photosynthesis converts sunlight energy into glucose and other high-energy sugars, which in turn serve as food for other organisms. In aerobic (oxidative) respiration, both plants and animals convert the glucose back into energy for growth and other life processes. The chemical equation for respiration shows that glucose is combined with oxygen to release energy.

    C6H12O6 + 6O2  6CO2 + 6H2O + energy

    Respiration is the breaking down of glucose for energy to grow and carry out other life processes (metabolism). It is important to emphasize that respiration takes place in the cells of both plants and animals. Have students recall what they know about the structure and function of the mitochondria from Lesson 1.

     

    Explain that there are three major cycles in cell respiration: glycolysis, the citric acid (or Krebs) cycle, and the electron transport chain.

    • Glycolysis: glucose is broken down into a simpler compound known as pyruvate.
    • Krebs cycle: Pyruvate is converted to a variety of energy-rich compounds, such as ATP and NADH (nicotinamide adenine dinucleotide).
    • Electron transport chain: The energy-rich compounds are converted to ATP.

    For guided practice, show students the Overview of Cell Respiration (S-B-7-2_Overview of Cell Respiration.doc). Have them use the diagram to answer these questions:

    • What molecule is broken down in cell respiration? (glucose)
    • What molecule is a product of all three stages? (ATP)
    • What is its function? (Store energy for cell processes)
    • What is also produced during glycolysis and the Krebs cycle? (CO2)

    Have students copy the diagram in their notes and label each stage, as well as the reactants and products.

    For independent practice, have students complete the Cell Respiration worksheet (S-B-7-2_Cell Respiration Worksheet and KEY.doc).

    Days 3–4: Comparing Photosynthesis and Cell Respiration

    To prepare, obtain Elodea and aquatic organisms. These can be ordered through a biological supply company, such as Carolina Biological Supply, or obtained at a local aquarium store. See related resources below.

    Lab Activity

    CAUTION: Make sure that students wear safety goggles during the entire lab. Have them follow the procedure to set up the lab, and then fill in the Design table. They should leave the experimental setup for at least an hour; overnight is preferable.

    Have students work in groups of 3–4 to design an experiment on the relationship between photosynthesis and respiration, using the questions shown on the Photosynthesis and Respiration Lab worksheet (S-B-7-2_Photosynthesis and Respiration Lab and KEY.doc). First, they should develop a hypothesis for each question and fill in the Develop a Hypothesis table on the worksheet.

    Explain that in order to test their hypotheses, they can use an acid-base indicator called Bromothymol blue solution. Show them the Bromothymol Blue Color Change and have them copy the sentences from the resource into their notes, filling in the blanks (S-B-7-2_Bromothymol Blue Color Change.doc). Bromothymol blue shows the presence of carbon dioxide by turning yellow, because carbon dioxide creates an acidic solution (i.e., carbonic acid). In low levels of carbon dioxide, the solution will appear blue.

     

    Acid (CO2 present)

    Neutral

    Base

    Yellow

    Blue-green

    Blue

    Describe the experimental procedure from the lab handout as you demonstrate it step by step. Have students follow the procedure for the four test tubes and fill out the Design Table on the lab handout.

    While students are waiting, have them complete the independent practice: Students work individually to complete the Comparison of Photosynthesis and Cell Respiration chart (S-B-7-2_Comparison and KEY.doc) and the Photosynthesis and Respiration: Plant Diagram (S-B-7-2_Plant Diagram.doc).Have students observe the changes in each of the test tubes, and write their observations and conclusions. Have them clean up all lab materials. Discuss their conclusions as a whole class. Ask students:

    • “Why did the control stay the same color?
    • What happened in the test tube with the snail and the Elodea?
    • What would happen if all the test tubes were kept in a dark place instead?”

    Students should be able to explain that the snail releases CO2 when it carries out respiration; this turns the solution yellow because it is acidic. The Elodea releases O2 when it carries out photosynthesis; this turns the solution blue because it is basic. The solution in the test tube with the snail and Elodea does not change because the processes of photosynthesis and respiration balance each other out.

    Conclude the lesson with a discussion of the overall energy transfer that occurs between photosynthesis and respiration.

    Extension:

    • Students who might need an opportunity for additional learning can creatively illustrate the light-dependent and Calvin cycle reactions in their notes.
    • Students who might need an opportunity for additional learning can write each of the reactants and products of photosynthesis and cell respiration on separate index cards. Have them arrange the index cards to show the process of photosynthesis, and then rearrange them to show the process of cell respiration, to reinforce that the processes are complementary.
    • Students who may be going beyond the standards can research the distinction between the light dependent reaction and the light independent reaction of photosynthesis and write the chemical equation for each reaction.
    • Students who may be going beyond the standards can view the animations of photosynthesis and cellular respiration by clicking those links at Virtual Cell Animation Collection available at http://vcell.ndsu.edu/animations/. Create a flowchart for the steps of one of the processes.
    • Design an experiment similar to the Photosynthesis and Cell Respiration lab, in which all of the test tubes are placed in a dark environment, including hypotheses and predictions.

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DRAFT 05/26/2011
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