Introduction: (Initial Observation)

Green plants use carbon-dioxide, water and light to build starch that is plant’s food. It is well known that plants can not live without water and light. But, what about carbon dioxide. Can plants live in a clean air with just oxygen and nitrogen? If human finds another planet with water, soil and oxygen and no carbon dioxide, can you grow some plants and vegetations there?

In this project we will try to find the answer to this question by performing some experiments.

Information Gathering:

Find out about plants, photosynthesis. Read books, magazines or ask professionals who might know in order to learn about plant growth, absorbing carbon-dioxide and releasing oxygen. Keep track of where you got your information from.

Following are some of the related information:

Department of agriculture have conducted experiments showing that increasing CO2 causes some plants to grow faster and larger and to use less water. Details…

Smithsonian environmental research center has performed some studies on the effects of elevated level of carbon dioxide on plant growth. They have concluded that:

1. Higher CO2 levels definitely increase ecosystem photosynthesis and biomass production in certain species; and they have consistently done so over the years of the research.

2. Higher CO2 levels also increase plant respiration Details …

Question/ Purpose:

What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.

The purpose of this experiment is to find out if plants can live without carbon dioxide.

Or

How does the amount of Carbon Dioxide gas affect the plant growth?

Identify Variables:

When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.

This is a sample of how you may define variables for the above question and the experiment number 4:

The independent variable is the amount of carbon dioxide available to the plant.

The dependent variable is the plants growth.

Control variables are light, temperature

Constants are the amount of water, nutrients and growth medium.

Hypothesis:

Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis.

My hypothesis is that plants can not live without carbon dioxide. Plants are organic material (contain carbon) and we know that neither soil nor water are a source of carbon. So the only source of carbon for plants is the air.

Another sample hypothesis:

If we increase the amount of carbon dioxide, then the plants will grow faster.

Experiment Design:

Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”

We are offering varieties of sample experiments for this project. You will need to do only one. So read all of them and pick your choice. If you need a graph, experiment 4 may be the best choice for you.

Experiment 1:

Introduction: In this experiment we will grow two identical plants in a controlled environment. Both plants will have the same amount of light and water. One of the plants will be in an oxygen bag and the other in an air bag. The results of this experiment will show if plants can live and grow without carbon dioxide.

Apparatus and Material:
For this experiment you will need 2 Geranium Plants (same size, shape and color), 2 large, clear plastic bags and an oxygen tank. small oxygen tanks can be purchased or rented from suppliers medical equipment.

Procedures:

1. 1. Place both bags flat on the ground (where you have enough light for both plants)
   2. Place one plant inside each bag (passed the middle, close to the end)
   3. Blow some air in the first bag and then close it’s opening so it remains inflated.
   4. Suck the air from the other bag and then fill the bag with oxygen gas. close it tight so it will remain inflated and filled with oxygen.
   5. inspect both plants every day for 7 days and record your observation.

Notes:

1. 1. If your air bag is not sealed properly, you may need to re-blow and re-seal it a few times during this experiment. The same may happen with your oxygen bag.
   2. Try to take pictures from all the steps of your experiment and use them for your display.
   3. You can use your bags or a temporary model of that also for your display.
   4. Instead of geranium plants, you can use any fast growing young plant or you may plant seeds for this experiment about 2 weeks prior to your experiment. You can also plant beans and use them for this project. If you are planting any seeds or beans, do not start your experiment until your plants have leafs.

Experiment 2:

Introduction: In this experiment we will grow two identical plants in a controlled environment. Both plants will have the same amount of light and water. One of the plants will be in a reduced carbon dioxide bag and the other in an air bag. We will reduce carbon dioxide by placing some carbon dioxide absorbent material next to the plant.

Apparatus and Material:
For this experiment you will need 2 Geranium Plants (same size, shape and color), 2 large, clear plastic bags, and some soda lime.

Soda lime is a mixture of calcium oxide and sodium or potassium hydroxide, used as a drying agent and carbon dioxide absorbent. Just lime that is calcium oxide (usually with added water, so it is actually calcium hydroxide) can also be used with similar results. You can order chemicals online from ChemicalStore.com. If you want to buy the materials locally, lime can be purchased from garden suppliers or hardware stores. Sodium hydroxide also can be purchased from some hardware stores. It is often used to open clogged drains. Sodium hydroxide is very corrosive. Rubber Gloves and goggles are required). Lime and sodium hydroxide are both strong alkaline material. That is why they absorb carbon dioxide (Carbon dioxide is a weak acid when it is absorbed by water. It is called Carbonic Acid).

Procedures:

1. 1. Place both bags flat on the ground (where you have enough light for both plants)
   2. Place one plant inside each bag (passed the middle, close to the end)
   3. Blow some air in the first bag and then close it’s opening so it remains inflated.
   4. Place a flat plate containing a strong soda-lime solution. Then blow some air in the bag and then close it’s opening so it remains inflated. In good conditions, a strong soda-lime solution can absorb up to 98% of the carbon-dioxide. So you can consider the contents of this bag as air without CO2.
   5. inspect both plants every day for 7 days and record your observation.

Notes:

1. 1. If your air bag is not sealed properly, you may need to re-blow and re-seal it a few times during this experiment. The same may happen with your reduced carbon dioxide bag.
   2. Try to take pictures from all the steps of your experiment and use them for your display.
   3. You can use your bags or a temporary model of that also for your display.
   4. Instead of geranium plants, you can use any fast growing young plant or you may plant seeds for this experiment about 2 weeks prior to your experiment. You can also plant beans and use them for this project. If you are planting any seeds or beans, do not start your experiment until your plants have leafs.

Experiment 3:

Introduction: From previous studies and experiments we know that plants use carbon-dioxide to make starch as plant’s food. So instead of waiting for days to see what happens to the plant, we just compare the amount of starch after one day under different levels of carbon-dioxide. If we find that process of producing starch is reduced by reducing carbon-dioxide, or is stopped when carbon-dioxide is absent, we can conclude that the life activity of plant is stopped and plant will die.

Objective To measure the amount of starch left in a leaf of a geranium plant under the following conditions; carbon dioxide increased, decreased and neither increased or decreased. To prove increased carbon dioxide increases the process of photosynthesis and increases the level of starch in the green plant.

Apparatus Needed
3 Geranium Plants (same size, shape and color)
3 2 gallon plastic bags with twist to close
2 250ml Beakers
1 500ml Beaker (For hot water, you can use aluminum or steel pans instead)
1 Hot Plate (has no flame and is the safest way to warm up water)
1 Pair of Plastic Tongues
4 Petri Dishes (or any similar plastic container dish)
1 1pt. 91% Isopropyl Alcohol (Do dissolve and wash away color pigments)
1 Package of Alka-Seltzer (To produce and increase carbon-dioxide)
1 50mL of Soda Lime (To absorb and reduce carbon dioxide)
1 Bottle of Potassium Iodide/ Iodine solution (Can be purchased from a pharmacy, but we got as a part of starch test kit of MiniScience.com)
3 Pieces of Cardboard
1 Pitcher of Water

Recommended Strategies

1. Mark plants A, B and C.
2. Put cardboard pieces at the bottom of each bag.
3. Put plant A in one bag with one 250mL beaker half filled with water. Place Alka- Seltzer in water, twist close.
4. Put plant B in one bag. Put 50mL of Soda Lime in a Petri dish and place in bag with plant B, twist close.
5. Put plant C in one bag. Twist close. (This is the “control” plant.)
6. Find a sunny place in your room to place all three plants. (The plants must have same amount of sunlight and water.) The plants are to set for one day.
7. After one day, remove plants from bags. Break off one leaf from each plant put in Petri dishes marked A, B, and C.
8. Half fill the 500mL beaker with water.
9. Fill the 250mL beaker with alcohol.
10. Place beaker with alcohol into beaker with water, on to the hot plate.
11. Take leaves one at a time and put in beaker with hot alcohol. Leave in for ten minutes.
12. Remove leaf with plastic tongues.
13. Place leaf on paper towel to dry, then place in Petri dish.
14. Place several drops of Iodine solution on each leaf.
15. Observe color change of the three leaves. (the darker the color (purple) the more starch. The lighter the color, the less starch.

Conclusion To determine how much starch is left under three conditions.
1. Carbon Dioxide increased.
2. Carbon Dioxide decreased.
3. Carbon Dioxide neither increased or decreased.

Discussion
1. What were the results of plant A, with Alka-Seltzer? Was the carbon dioxide increased, decreased, or remained the same?
2. What were the results of plant B, with the soda lime? Was the carbon dioxide increased, decreased, or remained the same?
3. What were the results of plant C, the “control” plant? Was the carbon dioxide increased, decreased, or remained the same?

Experiment 4: How does carbon dioxide affect the plant growth?

Introduction: In this experiment you will grow plant in three different carbon dioxide conditions. These 3 conditions are:

1. Reduced Carbon Dioxide Air
2. Normal Carbon Dioxide Air
3. Increased Carbon Dioxide Air

You will observe and record plant growth in these conditions.

Procedure:

1. Prepare 3 growth chambers large enough to accommodate 3 small flower pots and a dish. You may use empty glass or plastic aquariums as growth chambers; however, most students don’t have 3 empty aquariums for their experiment and need to construct their own growth chambers.

You can construct your growth chambers by making a wooden cube frame and cover it with clear plastics. You may also use carton boxes as growth chambers. To do this simply remove the top side of boxes and cover them with clear plastic or Plexiglas. You may also cut windows on the sides and cover the windows with plastic too. Windows allow more light enter the chambers and as you know sufficient light is needed for plants to grow. If you want to use carton boxes, also cover inside the box with white paper, white paint or aluminum foil. These colors reflect the light and make more light available to plants.

For the reduced carbon dioxide chamber, place a dish or tray inside the chamber and fill it to half with an alkaline substance that absorbs carbon dioxide. A good carbon dioxide absorber is a 20% solution of lime or a 5% solution of caustic soda.

For the normal Carbon dioxide chamber, place a dish or tray inside the chamber and fill it up to half with water.

For the increased carbon dioxide chamber, place a dish or tray inside the chamber and fill it to half with carbonated water.

2. Label your chambers as “Reduced Carbon Dioxide”, “Normal Carbon Dioxide”, and “Increased Carbon Dioxide”.

3. Place 3 young same size plants in each chamber. You may buy plants for your experiment or you may plant seeds for this experiment about 2 weeks prior to your experiment. You can also plant beans and use them for this project. If you are planting any seeds or beans, do not start your experiment until your plants have leafs.

4. Every day open the chambers for about 10 minutes, water the plants, replace the solutions in trays with fresh solutions of the same type. Record your observations. Repeat this for about 15 days.

5. On the last day, remove all plants and record average plant height, average number of leaves and the size of the largest leaf in each group. Record your results in a table like this. (The size of the largest leaf can be the area or the length of the leaf)

Make a bar chart for plant height. User one bar for each carbon dioxide condition. The height of the bar will be the average plant height.

Make a another bar chart for average number of leaves in plants. User one bar for each group. The height of the bar will be the average number of leaves.

Make a final bar chart for maximum leaf size in each group. User one bar for each group. The height of the bar will be the size of the largest leaf in that group. (or the average size of the largest leaves in each group)

Materials and Equipment:

Can be extracted from experiment design.

Oxygen tanks are usually rented. Small tanks are available at healthcare suppliers. Larger one are available at Industrial gas suppliers. You may need to leave a security deposit for the gas cylinder. You may find gas suppliers or healthcare suppliers of your area in your local phone book or online at www.superpages.com.

Results of Experiment (Observation):

Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.

Calculations:

Description

Summary of Results:

Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.

It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.

Conclusion:

Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.

Related Questions & Answers:

What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.

Possible Errors:

If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.

If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.

References:

Visit a local library and find books related to botany and plants biology. Many of these books have discussions about how plants use carbon dioxide and nitrogen from the air. (Carbon dioxide will be absorbed by plants leaves and Nitrogen will be absorbed by plants roots). Following are some web resources.

Carbon Dioxide is good of the environment

Carbon Dioxide

Carbon dioxide is essential to the growth of all plants

Carbon Dioxide Enrichment

Sample project

The Effect of Exposure to High Concentrations of Carbon Dioxide on a Kalanchoe blossfeldiana Leaf’s Photosynthetic Activity

Abstract.

For plants to perform photosynthesis, they require the intake of carbon dioxide. In this experiment, the environment’s carbon dioxide concentration was changed to determine at what percentage of carbon dioxide, the leaves of Kalanchoe blossfeldiana would photosynthesize the best at. This was determined by removing as much air from the leaf as possible, causing the leaf to sink. The leaves were placed in a beaker with CO2 and water, under a light. The oxygen formed from photosynthesis would cause the leaf to rise and float. The time it took for the leaf to reach the surface was our measuring stick. CO2 was taken from Sprite, a carbonated soda. CO2 concentrations were altered by changing the CO2: water ratio in the beaker. At higher concentrations of carbon dioxide, photosynthesis was slower.

Introduction.

Plants need carbon dioxide and light energy to carry on photosynthesis. Most plants get their CO2 from the air and the plants photosynthetic activity can be altered by the plant’s environment[1]. A previous experiment proved that plant leaves can also use CO2 from baking soda to carry on photosynthesis[2]. Sodas are carbonated drinks and therefore contain CO2. A soda like Sprite should be able to give a plant enough CO2 to survive.

It has been shown that plants have made adaptations to environmental conditions to make photosynthesis run better for them[3]. We wanted to determine the ideal CO2 concentration for maximum photosynthetic activity of the Kalanchoe blossfeldiana leaves. A vacuum took as much air out of the leaf as possible and replaced it with sodium bicarbonate causing the leaf to sink in liquids. The leaf was then placed in an environment where it could photosynthesize. Sprite provided CO2, DI H2O provided H2O, and a lamp provided light energy. The amount of Sprite was adjusted to change the carbon dioxide concentration. Photosynthetic activity was measured by the amount of time it took for the leaves to float to the surface of a common solution. With the information gained from this experiment proper CO2 concentration adjustments could be made to encourage the growth of these plants in controlled conditions, like greenhouses.

Materials and Method.

No special equipment will be needed for this experiment.

A vacuum was created with an aspirator and attached to it was a test tube that contained 30 mL of 0.6M sodium bicarbonate and three Kalanchoe blossfeldiana leaf specimens. Each of these specimens was a disc cut from a leaf and were all the same size, about 1.5 cm in diameter. In this report these discs will simply be referred to as the leaves. This vacuum sucked all the air out of the leaf and replaced it with the sodium bicarbonate solution. This exchange of gas for liquid made the leaf heavier and made the leaves lose their buoyancy. The vacuum was turned on until a fair amount of bubbles could be seen rising from the solution and forming on the leaf.

A 0% Sprite-solution was made with 50mL of DI water. The three leaves were placed into this solution. To make sure the leaves would not float to the surface, they were placed on a safety pin. The needle part of the safety was stuck through the center of the three leaves, and they were spaced evenly apart along the needle. In this setup the leaves would be able to photosynthesize. They have CO2 from the Sprite, water from the DI water, and light from the lamp. The leaves were left in this solution for two minutes.

The leaves were then taken off the safety pin and placed in 50mL of O.6M sodium bicarbonate under a lamp. A timer was started when the leaves entered the solution. In the Sprite solution, the leaves should have started photosynthesizing. This would cause the leaves to produce oxygen which would refill the leaves with air and make it buoyant again. The times that the leaves rose to the surface is the indicator of how the soda affected the leaf’s photosynthesis.

This procedure was repeated two more times with Sprite-solutions of 15% and 30% Sprite. The rest of the 50mL solution was DI water. The same lamp was used and kept the same distance from the leaves. During the brief exposure to different amounts of CO2, the leaves photosynthesized at different rates and had different amounts of gas in them. When placed in the sodium bicarbonate solution, they should have photosynthesized at the same rate. The leaves that had photosynthesized more in the Sprite solution would have risen faster.

Results.

The results collected in this experiment are the amount of time it took for the leaves to rise to the surface of the sodium bicarbonate solution. Table 1 shows the time that the leaves reached the surface for each soda concentration and the average time for all three leaves.

Table 1. Time That Each Leaf Reached the Solution Surface and the Average Time for the Three Leaves Under Varying Conditions

Units = Minutes: Seconds

Based on the average time that the leaf reached the surface, it can be concluded that higher soda concentrations decrease photosynthetic activity. However, by looking at the individual leaf times no pattern can be seen. The first leaf’s time went down then up. The second leaf’s time only went up. The third leaf’s time went down then up. These patterns can be seen in Figure 1. The main effect of higher CO2 concentration was an increase of 81 and 2/3 seconds or about 1 minute and 22 seconds. See Appendix 1.

Figure 1.

Despite the varying time patterns, all of the leaves placed in the 30% sprite solution took longer than their corresponding leaf that was placed in the 0% Sprite solution.

Discussion.

The data shows that increased concentrations of soda will increase the amount of time that the leaf needs to reach the solution’s surface. From this, we can conclude that higher concentrations of carbon dioxide will decrease the photosynthetic activity of a Kalanchoe blossfeldiana leaf. Air is less than 1% carbon dioxide. Places with a naturally high carbon dioxide concentration that help plant photosynthesis probably do not have carbon dioxide concentrations of greater than 1%. In a solution with 30% soda, bubbles of carbon dioxide could be seen rising to the surface and clinging to the beaker. The concentration of carbon dioxide in this solution is probably more than 1%, though this is not proven. The concentration may be high enough that the carbon dioxide inhibits photosynthesis. However, most books will say that higher amounts of carbon dioxide will increase photosynthetic activity. This may be due to the fact that no natural environment will provide high enough carbon dioxide concentrations to be harmful. Therefore, it can be concluded that carbon dioxide will help photosynthesis to a certain point. The effect of carbon dioxide may be shaped like a bell. Carbon dioxide helps photosynthesis up to a certain point and then harms it.

Other things affecting the leaf’s photosynthetic activity could be the other substances found in Sprite. The high fructose corn syrup and/or sucrose in the Sprite may have been taken up by the leaf. These sugars may have slowed the leaf’s photosynthetic activity. Citric acid present in the Sprite may have initiated cellular respiration which would use the oxygen that was produced by the leaf from photosynthesis and produced more carbon dioxide. Other ingredients include sodium citrate and sodium benzoate. The high amounts of sodium could have had some type of effect on the leaf also. It is unknown what effects all the components of the Sprite had on the leaf.

The data cannot be considered exact for many reasons. A beaker of sodium bicarbonate was obtained at the beginning of a testing period. Sodium bicarbonate used for testing a concentration of 30% Sprite would have been in the beaker for about 30 minutes. A considerable amount of carbon dioxide could have escaped from the solution by this time. The percentage of carbon dioxide in the sodium bicarbonate would have been different. The sodium bicarbonate should have been kept in an air-tight container like the Sprite was. Carbon dioxide from the soda and from the sodium bicarbonate solution was escaping the solution when the molecules hit the surface. This meant that the carbon dioxide level was dropping not only because the leaf was using it but also because CO2 was lost to the environment. In a natural environment, carbon dioxide level would probably be fairly stable.

The leaves could have naturally different photosynthetic rates due to differing amounts of chlorophyll. Some leaves could have been dying while others were flourishing. The conditions of the all the leaves were not identical.

As mentioned before, it is not certain what the exact concentration of CO2 was in the experiment. Further experiments should have a better way to measure and control the CO2 concentration and the environment. There should not be other things, like other ingredients from the Sprite, to affect the leaf’s photosynthetic activity. Based on the hypothesis that carbon dioxide does have a bell shaped effect on photosynthesis, lower concentrations of carbon dioxide should be tested. Doing this could help determine a more exact concentration at which CO2 becomes harmful. Bioengineering of plants is fast becoming the focus of many scientists. By determining under what carbon dioxide level plants grow best, they can set green houses to the appropriate settings to encourage rapid growth for more plants to do testing on. The planting of trees is also common activity to replenish the world’s vegetation. By knowing under what plants grow better under certain conditions, the best suited plant could be chosen for planting at a certain area. The carbon dioxide concentration can vary from urban to rural settings and plants that grow better with higher amounts of carbon dioxide should be grown in urban areas, which contains more than three times more carbon dioxide[1].

References.

1. Rosenberg, Jerome L. Photosynthesis. New York, New York: Holt, Rineheart, and Winston, Inc., 1965.
1. Li, Jessica. Monta Vista Biology AP Lab Notebook. Cupertino, California: Jessica Li, 1999.
1. http://esg-www.mit.edu:8001/esgbio/ps/psdir.html