Plant's Nanomachinery for Photosynthesis and Nanotechnology for Solar Energy Conversion

Learning Resource Type

Lesson Plan

Subject Area

Science

Grade(s)

7

Overview

Understanding the energy conversion capability of photosynthesis and the artificial nanostructured photocatalysts contrast biotic and abiotic systems, while demonstrating the efficiency of photosynthesis compared to titanium dioxide nanoparticles in generating gas production volumetrically. The experiment results transition to a discussion of photosynthesis and the organelles within the cell where it takes place.  This lesson explores  light energy capture and transformation into chemical energy during photosynthesis.  The lesson can lead to discussion of renewable energy conversion methods and nanotechnology, to help advance nanoscience research to solve the challenging energy issues in the future.     

Science (2015) Grade(s): 7

SC15.7.3

Construct an explanation of the function (e.g., mitochondria releasing energy during cellular respiration) of specific cell structures (i.e., nucleus, cell membrane, cell wall, ribosomes, mitochondria, chloroplasts, and vacuoles) for maintaining a stable environment.

UP:SC15.7.3

Vocabulary

  • Explanation
  • Structure
  • Function
  • Organelle
  • Nucleus
  • Cell membrane
  • Cell wall
  • Ribosome
  • Mitochondria
  • Chloroplast
  • Vacuole
  • Homeostasis
  • System
  • Valid
  • Reliable

Knowledge

Students know:
  • Function of organelles (i.e., nucleus, cell membrane, cell wall, ribosome, mitochondria, chloroplast, vacuole).
  • Roles of organelles in maintaining a stable environment.
  • Key differences between animal and plant cells (e.g., Plant cells have a cell wall, chloroplasts, etc.).

Skills

Students are able to:
  • Articulate a statement that relates a given phenomenon to a scientific idea, including how different parts of a cell contribute to how the cell functions as a whole, both separately and together with other structures.

Understanding

Students understand that:
  • The function of an organelle contributes to the overall function of the cell, both separately and together with other organelles, to maintain a stable environment.
  • Organelles function together as parts of a system (the cell).
  • Organelles function together as parts of a system that determines cellular function.
  • Energy is required to maintain a stable environment.

Scientific and Engineering Practices

Constructing Explanations and Designing Solutions

Crosscutting Concepts

Structure and Function
Science (2015) Grade(s): 7

SC15.7.5

Examine the cycling of matter between abiotic and biotic parts of ecosystems to explain the flow of energy and the conservation of matter.

UP:SC15.7.5

Vocabulary

  • Abiotic
  • Organisms as producers, consumers, and/or decomposers
  • Biotic
  • Evaluate
  • Ecosystem
  • Communicate
  • Chemical reaction
  • Molecules
  • Photosynthesis
  • Food web
  • Cellular respiration
  • Energy
  • Matter
  • Energy transfer

Knowledge

Students know:
  • Organisms can be classified as producers, consumers, and/or decomposers.
  • Abiotic parts of an ecosystem provide matter to biotic organisms.
  • Biotic organisms of an ecosystem provide matter to abiotic parts.
  • Energy flow within an ecosystem.
  • The number of each type of atom is the same before and after chemical reactions, indicating that the matter ingested as food is conserved as it moves through an organism to support growth.
  • During cellular respiration, molecules of food undergo chemical reactions with oxygen to release stored energy.
  • The atoms in food are rearranged through chemical reactions to form new molecules.
  • All matter (atoms) used by the organism for growth comes from the products of the chemical reactions involving the matter taken in by the organism.
  • Food molecules taken in by the organism are broken down and can then be rearranged to become the molecules that comprise the organism (e.g., the proteins and other macromolecules in a hamburger can be broken down and used to make a variety of tissues in humans).
  • As food molecules are rearranged, energy is released and can be used to support other processes within the organisms.
  • Plants, algae, and photosynthetic microorganisms require energy and must take in carbon dioxide and water to survive.
  • Energy from the sun is used to combine molecules (e.g., carbon dioxide and water) into food molecules (e.g., sugar) and oxygen.
  • Animals take in food and oxygen to provide energy and materials for growth and survival.
  • Some animals eat plants algae and photosynthetic microorganisms, and some animals eat other animals, which have themselves eaten photosynthetic organisms.

Skills

Students are able to:
  • Articulate a statement that relates a given phenomenon to a scientific idea, including the cycling of matter and flow of energy among biotic and abiotic parts of ecosystems.
  • Identify and use multiple valid and reliable sources of evidence to construct an explanation.
  • Use reasoning to connect the evidence and support an explanation.
  • Obtain information about how food is broken down through chemical reactions to create new molecules that support growth and/or release energy as it moves through an organism from published, grade-level appropriate material from multiple sources.
  • Determine and describe whether the gathered information is relevant.
  • Use information to communicate how food is broken down through chemical reactions to create new molecules that support growth and/or release energy as it moves through an organism.
  • Articulate a statement that relates a given phenomenon to a scientific idea, including the idea that photosynthesis and cellular respiration cycle matter and energy.
  • Identify and use multiple valid and reliable sources of evidence to explain the roles of photosynthesis and cellular respiration in cycling matter and energy.
  • Use reasoning to connect the evidence and support an explanation of the roles of photosynthesis and cellular respiration in the cycling of matter and flow of energy into and out of organisms.

Understanding

Students understand that:
  • There is a transfer of energy and a cycling of atoms that were originally captured from the nonliving parts of the ecosystem by the producers.
  • The transfer of matter (atoms) and energy between living and nonliving parts of the ecosystem at every level within the system, which allows matter to cycle and energy to flow within and outside of the system.
  • The atoms that make up the organisms in an ecosystem are cycled repeatedly between the living and nonliving parts of the ecosystem.
  • Matter and energy are conserved through transfers within and outside of the ecosystem.
  • Relationship among producers, consumers, and decomposers (e.g., decomposers break down consumers and producers via chemical reactions and use the energy released from rearranging those molecules for growth and development.
  • Within individual organisms, food moves through a series of chemical reactions in which it is broken down and rearranged to form new molecules, to support growth, or to release energy.
  • Plants, algae, and photosynthetic microorganisms take in matter and use energy from the sun to produce organic molecules that they can use or store, and release oxygen into the environment through photosynthesis.
  • Plants use the food they have made for energy, growth, etc.
  • Animals depend on matter from plants for growth and survival, including the following:
    • Eating photosynthetic organisms, thus acquiring the matter they contain, that they gained through photosynthesis.
    • Breathing in oxygen, which was released when plants completed photosynthesis.
  • Animals acquire their food from photosynthetic organisms (or organisms that have eaten those organisms) and their oxygen from the products of photosynthesis, all food and most of the oxygen animals use from life processes are the results of energy from the sun driving matter flows through the process of photosynthesis.
  • Photosynthesis has an important role in energy and matter cycling within plants as well as from plants and other organisms.

Scientific and Engineering Practices

Constructing Explanations and Designing Solutions; Asking Questions and Defining Problems; Obtaining, Evaluating, and Communicating Information

Crosscutting Concepts

Energy and Matter

Primary Learning Objectives

1.  Conducting an experiment, students will explain the photosynthetic efficiency difference in the O2 production between using a green plant (chloroplasts) vs two control samples with a soda solution in the presence and absence of TiO2 nanoparticles.

2.  Students will describe the function of chloroplasts as structures that capture light (energy) for the food making process of photosynthesis

3.  Students will write the process of photosynthesis identifying the reactants, products, and source of energy for the process.

 

Procedures/Activities

Engage

As a team of scientists working on the Mars, the production of oxygen is critical to survival.  You and your team members are working toward  creating inexpensive, sustainable and efficient ways to generate oxygen gas quickly.  You are currently considering plants, like spinach for the production of oxygen or other substances such as particular nanoparticles.  

Teams of 3-4 students should consider the following questions: Why would your team consider using plants to generate oxygen?   What would be needed for the plants to generate oxygen?   After teams write their responses to the scenario questions, as a class students should discuss their ideas.

 

Or you may choose to do the following first and then ask why a mission to the Mars would consider using photosynthesis for oxygen production. What is the advantage of do so?

 

Ask students what they know about photosynthesis, in particular what materials are needed for photosynthesis and what products of the important energy conversion system.  Allow them to discuss their ideas to ascertain their prior knowledge of the photosynthetic process. These can be drawn on the board and the teams describe what should be included with each sphere.

Explore

 (Note: tools and items for the activity are indicated by the numerical label shown in the materials list.)

 

As a team, students will conduct the following activity to find out which of the materials: Which substances produce more oxygen in a given time frame.  In other words, which tube  exhibits the highest efficiency of oxygen production.

 

Students follow the instructions:

 

a.

Measure 2 grams of baking soda (sodium bicarbonate), and transfer it into one of the clean plastic cups. 

b.

Add water into the above cup to dissolve the baking soda powder by stirring the solution with plastic knife, continue adding water to fill the plastic cup to obtain a clear aqueous solution of baking soda. Fill 80% of the cup with water or to the  mark on the cup to avoid spilling the solution on table.

c.

Label the three test tubes A, B and C, respectively.

d.

Take 3-4 pieces of clean spinach leaves from fresh spinach bag. Tear  them to quarter inch in size (or cut with scissors) and place all of pieces into test tube B.  

e.

Fully load the plastic transfer pipette with 1% TiO2 nanoparticle solution, and place it into test tube C. Repeat the transfer step two more times.  

f.

 Fill each of the test tubes A, B and C with 40 mL baking soda solution (prepared in step b) using a graduated cylinder. Ask your team member to help hold the test tube in vertical to avoid spilling of solution.

g.

Plug the three rubber stoppers (containing tubing) in all three individual test tubes A, B and C, respectively to seal the necks of all tubes to prevent gas leakage. 

h.

Place all three test tubes in the second plastic cup, and fill the cup with ~160 ml water (called a water bath). Avoid heating the test tubes directly under the light because gas can expand its volume by increasing its temperature at constant pressure (ideal gas law!)  At this point, you should keep all three test tubes stable to avoid any volume changes to happen. 

i.

Take one of the three clean glass capillary tubes. Ask the teacher to replace one for you if it already contains water droplet or contaminated. Dip about 1 cm of one side of the tube into the color indicator (pink) solution.  The pink solution will be taken into the dipped portion of the tube due to capillary force of the tube.     

j.

Make sure you turn off the room light. We will use a light source (lamps) to trigger the photosynthesis reaction in the following steps.

Insert the colored side of the capillary tube into the open rubber tube side of the test tube while holding the capillary tube lying in horizontal position.  Please not to apply too much force when the capillary tube is inserted to the plastic tube to avoid breaking the glass tube.

k.

Repeat step i and j for test tube B and C using the other two available capillary tubes after loading them with color indicator.  Always hold the capillary tubes lying in horizontal position and the solution in your test tube stable! 

l.

Place three capillary tubes loaded with pink color indicator on the printed paper ruler, and align the end of the pink column along the zero cm as shown in Figure 2.

Tube A contains baking soda, water;

Tube B contains baking soda, water and spinach; and

Tube C contains water, baking soda, and TiO2.

Make sure to identify which capillary tube belongs to which test tube. It is important not to apply any force to the rubber stoppers or the plastic tube in order to maintain the zero location of the pink color indicators.  

Caution: Check the color indicators to make sure they are stable in the capillary tubes and then Do Not Move Them; otherwise you will disconnect the capillary tube from the rubber tube and need reset the indicator to the end of the capillary tube, then make connection again.

m.

Use a clock to time the reaction of the three test tubes. Begin by turning on the light and place the lamp about 15 cm away from the test tubes as shown in Figure 3.  Record the location of the pink color column along the paper ruler. Take one data point per 30 sec and record your data in table 1. 

 

 

Figure 2. Alignment of the pink color indicator in capillary tube with a paper ruler.

 

 

Sec

0

30

60

90

120

150

180

210

240

270

300

330

360

390

A

 

 

 

 

 

 

 

 

 

 

 

 

 

 

B

 

 

 

 

 

 

 

 

 

 

 

 

 

 

C

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 1. Record the location (by cm) of the pink color indicator column in each of the capillary tube from A to C under light. 

 

Explain

After completing the experiment and recording data. Use the following questions to guide the discussion regarding the concepts and findings.

        (1)        Do you see any location change for any of the three pink color indicators? Explain how you think the colored liquid in an empty capillary tube moves? Rank the speed of the three pink colored liquids from fastest to slowest when they move inside the capillary tubes under light.

        (2)        Which, if any, colored liquid did not move?  How can you explain this?

        (3)        Which test tube (A, B and C) did the color liquid move fastest? What are the contents in the test tube?  Using the tube contents in your explanation, what do you think is occurring?

        (4)        Explain why test tube A is compared to B to explain the movement of their corresponding pink colored liquids?  What is test tube A called in an experiment?

        (5)        Compare test tube A and B, which one has a chemical reaction occurring under light? Why do you need spinach leaf?   Is spinach considered biotic or abiotic?

        (6)        What important plant process is occurring in test tube B? What are the products of the reaction? What are the reactants?  What does the chemical equation of the photosynthetic process look like?

        (7)        What is the role of baking soda (sodium bicarbonate) in the test tubes?

        (8)        Examining test tube B, what is the purpose of the light in photosynthesis?

        (9)        Light energy is converted into what type of energy in photosynthesis? What is the key product of photosynthesis?

      (10)      What structures are present in plant cells like spinach capture light energy?

      (11)      What is the purpose of baking soda (sodium bicarbonate) in test tube B?

      (12)      Compare B and C, which indicator moves faster? Did both of them move?

      (13)      Explain what might be produced in C if the pink colored liquid moves?  

      (14)      What might be a reason (test tube C) titanium dioxide nanoparticles are less efficient in producing gas?

      (15)      Which of the tubes is more efficient in producing oxygen?

       

  Elaborate/Extend


After discussion of the investigation and the concepts associated with photosynthesis.  Extend the ideas by having students do Part 1 and Part 2 below.

Part 1:

     Graph the data for Test tubes A, B, and C (Distance vs Time)

 Compare and contrast the data plotted on the graph.

Part 2:

     Now that you have carried out you experiments for examining the efficiency of oxygen production with spinach versus titanium dioxide.  As a scientific team member based on what you have learned, write up a short report about which of the two designs photosynthetic systems (using plants to produce oxygen) versus artificial systems (using chemicals like TiO2) would be most effective for oxygen production on a Mars station. In the report include describe photosynthesis and details about the plant structures where it occurs.  What aspects will you have to consider to make the system on Mars sustainable (reusable), least expensive and a long term solution for oxygen production.

 

 

 

 

 

Engage

 

As a team of scientists working on the Mars, the production of oxygen is critical to survival.  You and your team members are working toward  creating inexpensive, sustainable and efficient ways to generate oxygen gas quickly.  You are currently considering plants, like spinach for the production of oxygen or other substances such as particular nanoparticles.  

Teams of 3-4 students should consider the following questions: Why would your team consider using plants to generate oxygen?   What would be needed for the plants to generate oxygen?   After teams write their responses to the scenario questions, as a class students should discuss their ideas.

 

Or you may choose to do the following first and then ask why a mission to the Mars would consider using photosynthesis for oxygen production. What is the advantage of do so?

 

Ask students what they know about photosynthesis, in particular what materials are needed for photosynthesis and what products of the important energy conversion system.  Allow them to discuss their ideas to ascertain their prior knowledge of the photosynthetic process. These can be drawn on the board and the teams describe what should be included with each sphere.

Explore

 (Note: tools and items for the activity are indicated by the numerical label shown in the materials list.)

 

As a team, students will conduct the following activity to find out which of the materials: Which substances produce more oxygen in a given time frame.  In other words, which tube  exhibits the highest efficiency of oxygen production.

 

Students follow the instructions:

 

a.

Measure 2 grams of baking soda (sodium bicarbonate), and transfer it into one of the clean plastic cups. 

b.

Add water into the above cup to dissolve the baking soda powder by stirring the solution with plastic knife, continue adding water to fill the plastic cup to obtain a clear aqueous solution of baking soda. Fill 80% of the cup with water or to the  mark on the cup to avoid spilling the solution on table.

c.

Label the three test tubes A, B and C, respectively.

d.

Take 3-4 pieces of clean spinach leaves from fresh spinach bag. Tear  them to quarter inch in size (or cut with scissors) and place all of pieces into test tube B.  

e.

Fully load the plastic transfer pipette with 1% TiO2 nanoparticle solution, and place it into test tube C. Repeat the transfer step two more times.  

f.

 Fill each of the test tubes A, B and C with 40 mL baking soda solution (prepared in step b) using a graduated cylinder. Ask your team member to help hold the test tube in vertical to avoid spilling of solution.

g.

Plug the three rubber stoppers (containing tubing) in all three individual test tubes A, B and C, respectively to seal the necks of all tubes to prevent gas leakage. 

h.

Place all three test tubes in the second plastic cup, and fill the cup with ~160 ml water (called a water bath). Avoid heating the test tubes directly under the light because gas can expand its volume by increasing its temperature at constant pressure (ideal gas law!)  At this point, you should keep all three test tubes stable to avoid any volume changes to happen. 

i.

Take one of the three clean glass capillary tubes. Ask the teacher to replace one for you if it already contains water droplet or contaminated. Dip about 1 cm of one side of the tube into the color indicator (pink) solution.  The pink solution will be taken into the dipped portion of the tube due to capillary force of the tube.     

j.

Make sure you turn off the room light. We will use a light source (lamps) to trigger the photosynthesis reaction in the following steps.

Insert the colored side of the capillary tube into the open rubber tube side of the test tube while holding the capillary tube lying in horizontal position.  Please not to apply too much force when the capillary tube is inserted to the plastic tube to avoid breaking the glass tube.

k.

Repeat step i and j for test tube B and C using the other two available capillary tubes after loading them with color indicator.  Always hold the capillary tubes lying in horizontal position and the solution in your test tube stable! 

l.

Place three capillary tubes loaded with pink color indicator on the printed paper ruler, and align the end of the pink column along the zero cm as shown in Figure 2.

Tube A contains baking soda, water;

Tube B contains baking soda, water and spinach; and

Tube C contains water, baking soda, and TiO2.

Make sure to identify which capillary tube belongs to which test tube. It is important not to apply any force to the rubber stoppers or the plastic tube in order to maintain the zero location of the pink color indicators.  

Caution: Check the color indicators to make sure they are stable in the capillary tubes and then Do Not Move Them; otherwise you will disconnect the capillary tube from the rubber tube and need reset the indicator to the end of the capillary tube, then make connection again.

m.

Use a clock to time the reaction of the three test tubes. Begin by turning on the light and place the lamp about 15 cm away from the test tubes as shown in Figure 3.  Record the location of the pink color column along the paper ruler. Take one data point per 30 sec and record your data in table 1. 

 

 

Figure 2. Alignment of the pink color indicator in capillary tube with a paper ruler.

 

 

Sec

0

30

60

90

120

150

180

210

240

270

300

330

360

390

A

 

 

 

 

 

 

 

 

 

 

 

 

 

 

B

 

 

 

 

 

 

 

 

 

 

 

 

 

 

C

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 1. Record the location (by cm) of the pink color indicator column in each of the capillary tube from A to C under light. 

 

Explain

After completing the experiment and recording data. Use the following questions to guide the discussion regarding the concepts and findings.

        (1)        Do you see any location change for any of the three pink color indicators? Explain how you think the colored liquid in an empty capillary tube moves? Rank the speed of the three pink colored liquids from fastest to slowest when they move inside the capillary tubes under light.

        (2)        Which, if any, colored liquid did not move?  How can you explain this?

        (3)        Which test tube (A, B and C) did the color liquid move fastest? What are the contents in the test tube?  Using the tube contents in your explanation, what do you think is occurring?

        (4)        Explain why test tube A is compared to B to explain the movement of their corresponding pink colored liquids?  What is test tube A called in an experiment?

        (5)        Compare test tube A and B, which one has a chemical reaction occurring under light? Why do you need spinach leaf?   Is spinach considered biotic or abiotic?

        (6)        What important plant process is occurring in test tube B? What are the products of the reaction? What are the reactants?  What does the chemical equation of the photosynthetic process look like?

        (7)        What is the role of baking soda (sodium bicarbonate) in the test tubes?

        (8)        Examining test tube B, what is the purpose of the light in photosynthesis?

        (9)        Light energy is converted into what type of energy in photosynthesis? What is the key product of photosynthesis?

      (10)      What structures are present in plant cells like spinach capture light energy?

      (11)      What is the purpose of baking soda (sodium bicarbonate) in test tube B?

      (12)      Compare B and C, which indicator moves faster? Did both of them move?

      (13)      Explain what might be produced in C if the pink colored liquid moves?  

      (14)      What might be a reason (test tube C) titanium dioxide nanoparticles are less efficient in producing gas?

      (15)      Which of the tubes is more efficient in producing oxygen?

       

  Elaborate/Extend


After discussion of the investigation and the concepts associated with photosynthesis.  Extend the ideas by having students do Part 1 and Part 2 below.

Part 1:

     Graph the data for Test tubes A, B, and C (Distance vs Time)

 Compare and contrast the data plotted on the graph.

Part 2:

     Now that you have carried out you experiments for examining the efficiency of oxygen production with spinach versus titanium dioxide.  As a scientific team member based on what you have learned, write up a short report about which of the two designs photosynthetic systems (using plants to produce oxygen) versus artificial systems (using chemicals like TiO2) would be most effective for oxygen production on a Mars station. In the report include describe photosynthesis and details about the plant structures where it occurs.  What aspects will you have to consider to make the system on Mars sustainable (reusable), least expensive and a long term solution for oxygen production.

 

 

 

 

 

Engage

 

As a team of scientists working on the Mars, the production of oxygen is critical to survival.  You and your team members are working toward  creating inexpensive, sustainable and efficient ways to generate oxygen gas quickly.  You are currently considering plants, like spinach for the production of oxygen or other substances such as particular nanoparticles.  

Teams of 3-4 students should consider the following questions: Why would your team consider using plants to generate oxygen?   What would be needed for the plants to generate oxygen?   After teams write their responses to the scenario questions, as a class students should discuss their ideas.

 

Or you may choose to do the following first and then ask why a mission to the Mars would consider using photosynthesis for oxygen production. What is the advantage of do so?

 

Ask students what they know about photosynthesis, in particular what materials are needed for photosynthesis and what products of the important energy conversion system.  Allow them to discuss their ideas to ascertain their prior knowledge of the photosynthetic process. These can be drawn on the board and the teams describe what should be included with each sphere.

Explore

 (Note: tools and items for the activity are indicated by the numerical label shown in the materials list.)

 

As a team, students will conduct the following activity to find out which of the materials: Which substances produce more oxygen in a given time frame.  In other words, which tube  exhibits the highest efficiency of oxygen production.

 

Students follow the instructions:

 

a.

Measure 2 grams of baking soda (sodium bicarbonate), and transfer it into one of the clean plastic cups. 

b.

Add water into the above cup to dissolve the baking soda powder by stirring the solution with plastic knife, continue adding water to fill the plastic cup to obtain a clear aqueous solution of baking soda. Fill 80% of the cup with water or to the  mark on the cup to avoid spilling the solution on table.

c.

Label the three test tubes A, B and C, respectively.

d.

Take 3-4 pieces of clean spinach leaves from fresh spinach bag. Tear  them to quarter inch in size (or cut with scissors) and place all of pieces into test tube B.  

e.

Fully load the plastic transfer pipette with 1% TiO2 nanoparticle solution, and place it into test tube C. Repeat the transfer step two more times.  

f.

 Fill each of the test tubes A, B and C with 40 mL baking soda solution (prepared in step b) using a graduated cylinder. Ask your team member to help hold the test tube in vertical to avoid spilling of solution.

g.

Plug the three rubber stoppers (containing tubing) in all three individual test tubes A, B and C, respectively to seal the necks of all tubes to prevent gas leakage. 

h.

Place all three test tubes in the second plastic cup, and fill the cup with ~160 ml water (called a water bath). Avoid heating the test tubes directly under the light because gas can expand its volume by increasing its temperature at constant pressure (ideal gas law!)  At this point, you should keep all three test tubes stable to avoid any volume changes to happen. 

i.

Take one of the three clean glass capillary tubes. Ask the teacher to replace one for you if it already contains water droplet or contaminated. Dip about 1 cm of one side of the tube into the color indicator (pink) solution.  The pink solution will be taken into the dipped portion of the tube due to capillary force of the tube.     

j.

Make sure you turn off the room light. We will use a light source (lamps) to trigger the photosynthesis reaction in the following steps.

Insert the colored side of the capillary tube into the open rubber tube side of the test tube while holding the capillary tube lying in horizontal position.  Please not to apply too much force when the capillary tube is inserted to the plastic tube to avoid breaking the glass tube.

k.

Repeat step i and j for test tube B and C using the other two available capillary tubes after loading them with color indicator.  Always hold the capillary tubes lying in horizontal position and the solution in your test tube stable! 

l.

Place three capillary tubes loaded with pink color indicator on the printed paper ruler, and align the end of the pink column along the zero cm as shown in Figure 2.

Tube A contains baking soda, water;

Tube B contains baking soda, water and spinach; and

Tube C contains water, baking soda, and TiO2.

Make sure to identify which capillary tube belongs to which test tube. It is important not to apply any force to the rubber stoppers or the plastic tube in order to maintain the zero location of the pink color indicators.  

Caution: Check the color indicators to make sure they are stable in the capillary tubes and then Do Not Move Them; otherwise you will disconnect the capillary tube from the rubber tube and need reset the indicator to the end of the capillary tube, then make connection again.

m.

Use a clock to time the reaction of the three test tubes. Begin by turning on the light and place the lamp about 15 cm away from the test tubes as shown in Figure 3.  Record the location of the pink color column along the paper ruler. Take one data point per 30 sec and record your data in table 1. 

 

 

Figure 2. Alignment of the pink color indicator in capillary tube with a paper ruler.

 

 

Sec

0

30

60

90

120

150

180

210

240

270

300

330

360

390

A

 

 

 

 

 

 

 

 

 

 

 

 

 

 

B

 

 

 

 

 

 

 

 

 

 

 

 

 

 

C

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 1. Record the location (by cm) of the pink color indicator column in each of the capillary tube from A to C under light. 

 

Explain

After completing the experiment and recording data. Use the following questions to guide the discussion regarding the concepts and findings.

        (1)        Do you see any location change for any of the three pink color indicators? Explain how you think the colored liquid in an empty capillary tube moves? Rank the speed of the three pink colored liquids from fastest to slowest when they move inside the capillary tubes under light.

        (2)        Which, if any, colored liquid did not move?  How can you explain this?

        (3)        Which test tube (A, B and C) did the color liquid move fastest? What are the contents in the test tube?  Using the tube contents in your explanation, what do you think is occurring?

        (4)        Explain why test tube A is compared to B to explain the movement of their corresponding pink colored liquids?  What is test tube A called in an experiment?

        (5)        Compare test tube A and B, which one has a chemical reaction occurring under light? Why do you need spinach leaf?   Is spinach considered biotic or abiotic?

        (6)        What important plant process is occurring in test tube B? What are the products of the reaction? What are the reactants?  What does the chemical equation of the photosynthetic process look like?

        (7)        What is the role of baking soda (sodium bicarbonate) in the test tubes?

        (8)        Examining test tube B, what is the purpose of the light in photosynthesis?

        (9)        Light energy is converted into what type of energy in photosynthesis? What is the key product of photosynthesis?

      (10)      What structures are present in plant cells like spinach capture light energy?

      (11)      What is the purpose of baking soda (sodium bicarbonate) in test tube B?

      (12)      Compare B and C, which indicator moves faster? Did both of them move?

      (13)      Explain what might be produced in C if the pink colored liquid moves?  

      (14)      What might be a reason (test tube C) titanium dioxide nanoparticles are less efficient in producing gas?

      (15)      Which of the tubes is more efficient in producing oxygen?

       

  Elaborate/Extend


After discussion of the investigation and the concepts associated with photosynthesis.  Extend the ideas by having students do Part 1 and Part 2 below.

Part 1:

     Graph the data for Test tubes A, B, and C (Distance vs Time)

 Compare and contrast the data plotted on the graph.

Part 2:

     Now that you have carried out you experiments for examining the efficiency of oxygen production with spinach versus titanium dioxide.  As a scientific team member based on what you have learned, write up a short report about which of the two designs photosynthetic systems (using plants to produce oxygen) versus artificial systems (using chemicals like TiO2) would be most effective for oxygen production on a Mars station. In the report include describe photosynthesis and details about the plant structures where it occurs.  What aspects will you have to consider to make the system on Mars sustainable (reusable), least expensive and a long term solution for oxygen production.

 

 

 

 

 

Engage

 

As a team of scientists working on the Mars, the production of oxygen is critical to survival.  You and your team members are working toward  creating inexpensive, sustainable and efficient ways to generate oxygen gas quickly.  You are currently considering plants, like spinach for the production of oxygen or other substances such as particular nanoparticles.  

Teams of 3-4 students should consider the following questions: Why would your team consider using plants to generate oxygen?   What would be needed for the plants to generate oxygen?   After teams write their responses to the scenario questions, as a class students should discuss their ideas.

 

Or you may choose to do the following first and then ask why a mission to the Mars would consider using photosynthesis for oxygen production. What is the advantage of do so?

 

Ask students what they know about photosynthesis, in particular what materials are needed for photosynthesis and what products of the important energy conversion system.  Allow them to discuss their ideas to ascertain their prior knowledge of the photosynthetic process. These can be drawn on the board and the teams describe what should be included with each sphere.

Explore

 (Note: tools and items for the activity are indicated by the numerical label shown in the materials list.)

 

As a team, students will conduct the following activity to find out which of the materials: Which substances produce more oxygen in a given time frame.  In other words, which tube  exhibits the highest efficiency of oxygen production.

 

Students follow the instructions:

 

a.

Measure 2 grams of baking soda (sodium bicarbonate), and transfer it into one of the clean plastic cups. 

b.

Add water into the above cup to dissolve the baking soda powder by stirring the solution with plastic knife, continue adding water to fill the plastic cup to obtain a clear aqueous solution of baking soda. Fill 80% of the cup with water or to the  mark on the cup to avoid spilling the solution on table.

c.

Label the three test tubes A, B and C, respectively.

d.

Take 3-4 pieces of clean spinach leaves from fresh spinach bag. Tear  them to quarter inch in size (or cut with scissors) and place all of pieces into test tube B.  

e.

Fully load the plastic transfer pipette with 1% TiO2 nanoparticle solution, and place it into test tube C. Repeat the transfer step two more times.  

f.

 Fill each of the test tubes A, B and C with 40 mL baking soda solution (prepared in step b) using a graduated cylinder. Ask your team member to help hold the test tube in vertical to avoid spilling of solution.

g.

Plug the three rubber stoppers (containing tubing) in all three individual test tubes A, B and C, respectively to seal the necks of all tubes to prevent gas leakage. 

h.

Place all three test tubes in the second plastic cup, and fill the cup with ~160 ml water (called a water bath). Avoid heating the test tubes directly under the light because gas can expand its volume by increasing its temperature at constant pressure (ideal gas law!)  At this point, you should keep all three test tubes stable to avoid any volume changes to happen. 

i.

Take one of the three clean glass capillary tubes. Ask the teacher to replace one for you if it already contains water droplet or contaminated. Dip about 1 cm of one side of the tube into the color indicator (pink) solution.  The pink solution will be taken into the dipped portion of the tube due to capillary force of the tube.     

j.

Make sure you turn off the room light. We will use a light source (lamps) to trigger the photosynthesis reaction in the following steps.

Insert the colored side of the capillary tube into the open rubber tube side of the test tube while holding the capillary tube lying in horizontal position.  Please not to apply too much force when the capillary tube is inserted to the plastic tube to avoid breaking the glass tube.

k.

Repeat step i and j for test tube B and C using the other two available capillary tubes after loading them with color indicator.  Always hold the capillary tubes lying in horizontal position and the solution in your test tube stable! 

l.

Place three capillary tubes loaded with pink color indicator on the printed paper ruler, and align the end of the pink column along the zero cm as shown in Figure 2.

Tube A contains baking soda, water;

Tube B contains baking soda, water and spinach; and

Tube C contains water, baking soda, and TiO2.

Make sure to identify which capillary tube belongs to which test tube. It is important not to apply any force to the rubber stoppers or the plastic tube in order to maintain the zero location of the pink color indicators.  

Caution: Check the color indicators to make sure they are stable in the capillary tubes and then Do Not Move Them; otherwise you will disconnect the capillary tube from the rubber tube and need reset the indicator to the end of the capillary tube, then make connection again.

m.

Use a clock to time the reaction of the three test tubes. Begin by turning on the light and place the lamp about 15 cm away from the test tubes as shown in Figure 3.  Record the location of the pink color column along the paper ruler. Take one data point per 30 sec and record your data in table 1. 

 

 

Figure 2. Alignment of the pink color indicator in capillary tube with a paper ruler.

 

 

Sec

0

30

60

90

120

150

180

210

240

270

300

330

360

390

A

 

 

 

 

 

 

 

 

 

 

 

 

 

 

B

 

 

 

 

 

 

 

 

 

 

 

 

 

 

C

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 1. Record the location (by cm) of the pink color indicator column in each of the capillary tube from A to C under light. 

 

Explain

After completing the experiment and recording data. Use the following questions to guide the discussion regarding the concepts and findings.

        (1)        Do you see any location change for any of the three pink color indicators? Explain how you think the colored liquid in an empty capillary tube moves? Rank the speed of the three pink colored liquids from fastest to slowest when they move inside the capillary tubes under light.

        (2)        Which, if any, colored liquid did not move?  How can you explain this?

        (3)        Which test tube (A, B and C) did the color liquid move fastest? What are the contents in the test tube?  Using the tube contents in your explanation, what do you think is occurring?

        (4)        Explain why test tube A is compared to B to explain the movement of their corresponding pink colored liquids?  What is test tube A called in an experiment?

        (5)        Compare test tube A and B, which one has a chemical reaction occurring under light? Why do you need spinach leaf?   Is spinach considered biotic or abiotic?

        (6)        What important plant process is occurring in test tube B? What are the products of the reaction? What are the reactants?  What does the chemical equation of the photosynthetic process look like?

        (7)        What is the role of baking soda (sodium bicarbonate) in the test tubes?

        (8)        Examining test tube B, what is the purpose of the light in photosynthesis?

        (9)        Light energy is converted into what type of energy in photosynthesis? What is the key product of photosynthesis?

      (10)      What structures are present in plant cells like spinach capture light energy?

      (11)      What is the purpose of baking soda (sodium bicarbonate) in test tube B?

      (12)      Compare B and C, which indicator moves faster? Did both of them move?

      (13)      Explain what might be produced in C if the pink colored liquid moves?  

      (14)      What might be a reason (test tube C) titanium dioxide nanoparticles are less efficient in producing gas?

      (15)      Which of the tubes is more efficient in producing oxygen?

       

  Elaborate/Extend


After discussion of the investigation and the concepts associated with photosynthesis.  Extend the ideas by having students do Part 1 and Part 2 below.

Part 1:

     Graph the data for Test tubes A, B, and C (Distance vs Time)

 Compare and contrast the data plotted on the graph.

Part 2:

     Now that you have carried out you experiments for examining the efficiency of oxygen production with spinach versus titanium dioxide.  As a scientific team member based on what you have learned, write up a short report about which of the two designs photosynthetic systems (using plants to produce oxygen) versus artificial systems (using chemicals like TiO2) would be most effective for oxygen production on a Mars station. In the report include describe photosynthesis and details about the plant structures where it occurs.  What aspects will you have to consider to make the system on Mars sustainable (reusable), least expensive and a long term solution for oxygen production.

 

 

 

 

Assessment Strategies

Informal assessment occurs during the engage, explore and  explanation phases.  The teacher asks appropriate questions as students conduct the experiment.  Questions listed for the teacher to ask during the explain portion of the lesson more thoroughly assess students knowledge of photosynthesis and the role of light energy to produce glucose (food as stored energy) leading to cellular respiration which leads to the discussion of energy flow (glucose plus oxygen releases energy for cell function) .

 

Formal Assessment:   

Each student will answer the following questions:

 

1.  Which of the following is not a product or by-product of photosynthesis?

      a. carbon dioxide            b. water           c. glucose           d. oxygen

 

2.  What is organelle carries out photosynthesis?

      a. chloroplasts         b. cytoplasm        c.  vacuole        d. ribosomes

 

3.  What pigment in spinach captures light to start photosynthesis?

      a.  chromoplast        b. chloroplasts     c. chlorophyll     d. leucophyll

 

4.  In photosynthesis light energy is captured in the green plant cells and converted in which of the following:

     a.  chemical energy  b. mechanical energy  c. electrical energy  

     d. none of these

 

5.  What gas is needed for photosynethis?

      a. water vapor         b.  oxygen             c. carbon monoxide     

      d. carbon dioxide

 

6   During photosynthesis what product stores energy for cell use?

      a.   water                 b. oxygen             c. glucose       d. none of these

7.   During the experiment what role did the sodium bicarbonate  (baking powder) play in photosynthesis?

      a. source of carbon dioxide   b. source of oxygen    c. source of energy  

      d. none of these

 

8.  Complete the following equation for photosynthesis?

                                                                         

               6CO2  + 12H2O                      C6H12O6  + 6H2O + 6O2

 

9. Which Test tube in the experiment represents an example of an abiotic and biotic system?

  1.     a.   Test Tube A                b. Test Tube B          c.  Test Tube C

10.  Give one characteristic of titanium dioxide nanoparticles that make it less efficient than the photosynthesis of spinach in the production of oxygen in this experiment?

 

Acceleration

Students could use a variety of resources to explore the light/dark reactions of photosynthesis as well as the detailed structure of chloroplasts (including stroma, grana, thylakoids). Building a model of the structure is a visual, creative way to share their understandings. Other options could be to have students build parts of the chloroplast and photograph them with a narrative showing the structures and their functions.

Intervention

Students may struggle with the equation of photosynthesis.   Students could actually build models of the reactants (e.g.  6 molecules of carbon dioxide, 12 molecules of water) the reconstruct them to make models of the products.  (one note:  the water reactant is different than the water product.   The oxygen in the water product is from the carbon dioxides.    This approach allows them to visualize the process and see the conservation of the matter in the reaction by using only the reactant molecules to make the product molecules.

Total Duration

61 to 90 Minutes

Background/Preparation

Students should be familiar with measurement for conducting the experiments and should have some basic background with chemical equations/reactions and symbols for chemicals.

Students should be familiar with the structure of plant cells and their organelles.

Students should be aware that visible light is comprised of spectrum of wavelengths (ROYGBV) of varying wavelengths.

 

TIPs for Teachers: (saves time)

 Teachers will need to either make a stock solution of baking soda (recommended) or have baking soda, filter paper, and balance available for the teams. 

Teacher take a sharpie to mark the cups at the 4/5 fill line.

Teachers need to make a 1% TiO2  stock solution

Teachers may put capillary tubing into the stoppers

 

Teachers need to prepare the capillary pipette tubes for student teams used in the measurement of O2 .

 

Teacher Background:

Photosynthesis is an energy conversion process taking place in plants that utilizes sun light to produce food (energy) for all kinds of activities of an organism. Typically, CO2 and water are converted in the presence of chlorophyll and sunlight into glucose, water  while oxygen is released to the atmosphere to be used by other living organisms including ourselves.  At the microscopic level, photosynthesis takes place by absorbing sun light using the plant’s photosynthetic reaction centers, the chloroplasts. The photosynthetic center contains chlorophylls that capture solar energy and starts the process by splitting water with oxygen being given off through stomata. Hydrogen is then chemically combined with carbon dioxide to form a simple sugar (C6H12O6) and water.  During cellular respiration glucose in the cells is oxidized to release energy which is used to convert adenosine diphosphate to adenosine triphosphate (ATP), the energy currency of the cells. ATP releases energy for cellular activity when a phosphate is split off and it become ADP.  (Balance equation for photosynthesis)

 

                                                     Light                    

                        6CO2  + 12H2O _____________  C6H12O6  + 6H2O + 6O2

 

 

Photosynthesis is considered an efficient energy conversion process that stores solar energy in chemical bonds that can be used for many applications. Similar to several artificial energy conversion systems (e.g., solar cell, and photoelectrochemical water splitting catalysts), photosynthesis produces useful energy that can be used to keep organisms alive and to power cell activities. In comparison to photosynthesis, artificial energy conversion systems use more stable inorganic or organic materials with much simpler charge storage/conversion configuration upon light absorption.

Energy conversion process of 25 nanometer (in diameter, 1 nanometer=10-9 meter) TiO2 nanoparticles is

 

Light (UV and blue) + TiO2 + CO2+ H2O_________H2 + CH4 + O2

 

TiO2 nanoparticles only absorb ultraviolet (UV) light with wavelengths less than 400 nm. When the short wavelengths are absorbed by TiO2, the electrons in TiO2 are excited to higher energy levels and they can reduce CO2 and/or water to produce methane and/or hydrogen gas, while the positive charges left would oxidize hydroxide to produce oxygen. Hydrogen production is important as it can be used as energy storage to be supplied to fuel cells with high energy intensity, and the product of burning hydrogen in oxygen is water so it serves as a clean energy source without producing CO2.

 

The lesson demonstrates gas production of TiO2 which is not as efficient as photosynthesis of spinach. This is because: 1) TiO2 absorbs only the portion of the light near ultraviolet end of the spectrum which is only a very small portion of solar energy (or our lamp). Chlorophyll in spinach captures a range of wavelengths in the visible light region; 2) spinach uses more sophisticated chemical reactions upon light absorption to convert water and CO2 to food and oxygen effectively; and 3) the structure of TiO2 nanoparticles are not optimal for effectively storaging charge into chemical bonds. In addition, the TiO2  sample of small nanoparticles has a total surface area that is much larger than spinach, this often result in the scattering of light by the nanoparticles which can decrease the actual light absorption by the nanoparticle. 

 

Materials and Resources

(Some items can be at a central location for all groups (e.g. stock baking soda solution, stock titanium dioxide solution, stock dye solution)

  For each team:

1:   1 plastic knife (or stirrer)

2:   1 plastic spoon

3:   2g baking soda

4:   2 transparent plastic cups or beakers

5:   3  50 ml test tube  

6:   4 L regular water

7:   1 fresh spinach bag

8:   1%  TiO2 titanium dioxide nanoparticle solution (stock solution recommended)

9:   3  1/16’’ ID rubber tube connected to a black rubber stopper for test tube  

10: 3  1/16 ‘’ glass capillary tube

11:  color indicator solution with Rhodamin B dye solution  (stock solution)

12:  100 Watt desk lamp

13:  clock for timing

14:  1 waste bottle  or a class waste container

15:   gloves

16:  plastic transfer pipette

17:  graduated cylinder

18:  graph paper (cm units)

Approved Date

2018-02-08
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