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Bottle Experiments with Mung Beans |
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Curricular Materials to Accompany the
McIntosh Apple Development Poster
Distributed by the Education Committee of the Botanical Society of America
Posted March 2001
Grade Levels: 6-8; 9-12
| Abstract: Plants respond behaviorally to changes in their environment by changing patterns of growth. The purpose of this lab is to explore how environmental features like light and volume of air influence growth in mung bean sprouts. Students will make predictions about the relationship between growth and environment, and test their predictions by growing sprouts in various sized plastic soda bottles. |
Objectives:
At the end of this exercise, students will be able to:
- Create a hypothesis about the effects of light and volume on the growth of mung bean sprouts.
- Observe, describe, and measure growth in mung bean sprouts.
- Record seedling growth in tabular form.
- Analyze data by calculating and graphing average seedling growth rates.
- Draw conclusions from results about the relationships between environment and growth in mung bean sprouts.
Background:
A seed contains its own life support system. When
stimulated to germinate, seeds use stored food reserves to grow into sprouts. A
sprout is a tender, often edible, seedling that is produced following seed
germination. As the sprout begins to develop and use up its stored reserves, the
seedling needs light and carbon dioxide to continue growth.
In this experiment, students will examine how the
amount of carbon dioxide and light changes the growth of a mung bean's sprout. The
equation of photosynthesis shows the relationships among carbon dioxide, light, and
growth:
6 CO2 + 12 H2O ---light----> C6H12O6 + 6 O2 + 6 H2O.
In this expression, C6H12O6 represents
simple sugars that are used by the plant for energy and structural materials like
wood. In other words, they are required for growth. Carbon dioxide (CO2
) is necessary for plants to form those simple sugars. Plants have the capacity to
use CO2 from the atmosphere for this purpose. If students experimentally
vary the amount of available carbon dioxide or light, they can observe their effects on
plant growth. In this exercise, seedlings are grown in plastic soda bottles.
The amount of CO2 varies with the volume of the bottle and light is manipulated
using aluminum foil. Additional volume will allow the seedlings to grow to a greater
size.
Light will have different effects depending on how long the sprouts are
allowed to grow. In all cases, sprouts grown in low light will be longer than
sprouts grown in more intense light. However, after the food reserves available in
the seed are used up, a plant grown in the dark will cease to grow and will be outgrown by
the plants grown in the light.
In addition to reinforcing plant science content, this
lab expects students to apply the scientific method. After learning basic
information about growth and photosynthesis, students formulate a hypothesis about the
growth of their mung bean sprouts in different treatments. After they have gathered
and compiled the data, students will compare their experimental results to their
original hypothesis and draw appropriate conclusions.
- Several 0.5, 1, and 2 Liter empty, clean, and clear plastic soda bottles. Rinse the bottles, but do not wash them in detergent which may inhibit seed germination or growth
- 10 mung bean seeds per student (Mung beans are available in most large grocery stores. However, if they are not, other peas or beans will work fine)
- paper towels
- aluminum foil
- metric rulers
- water
Procedure:
Note: Mung beans should not be soaked in water;
they should be moistened with the damp paper towels. The bottles should not have
excess water in them prior to the lab.
- After giving the students information about plant growth, have them write a hypothesis about the relationship between the experimental variables and plant growth.
- Assign students to a soda bottle size (0.5, 1, or 2 Liter). There should be equal numbers of each size soda bottle distributed among the class.
- Have students place 10 mung beans in their soda bottle.
- Each student should rip one paper towel into several pieces (approximately 1 inch by 1 inch) and place them in their soda bottle.
- Students should fill the cap of their soda bottle with water and pour the water into the soda bottle. No more than this amount of water is required.
- Securely tighten the cap and do not reopened during the experiment.
- Assign the students to light and dark treatments. Each size bottle should have at least two light and two dark treatments.
- Record the treatments.
- Cover dark treatment soda bottles with aluminum foil.
- Place all bottles near the windowsill so the light treatments will receive sunlight. Keep both light and dark treatments to maintain as equal environments within them as possible. However, note that light treatments will be exposed to higher temperatures.
- Each day, have the students measure and record the length of the sprouts to the nearest mm using a metric ruler. Record the length of five sprouts and calculate the average. Record this information. Students will record data for 10 days.
- At the end of each recording for the day, have the students calculate averages for each treatment.
- After 10 days, create a line graph with the x-axis representing time in days and the y-axis growth in length. Use a different line showing averages for each of the treatments. There should be a total of 6 lines.
- Have students draw conclusions from their data and results. They should compare their experimental results to their original hypothesis. If their hypotheses are not supported by their results, encourage students to explore reasons for the lack of support. Do the results lead to new hypotheses? Students (and scientists) learn from experiments that seem to have failed because hypotheses are not supported. Hypothesis testing involves an evaluation of the causes of patterns and observations. One is not always correct about those causes at the outset.
Books:
Introductory plant biology books will discuss germination and growth of seedlings. Several are listed below.
- Raven, P.H., R.F. Evert, S.E. Eichhorn. 1998. Biology of Plants. Worth Publishers Inc., New York.
- Stern, Kingsley R. 2000. Introductory Plant Biology, 8th ed. McGraw Hill, Dubuque, IA.
- Uno, Gordon, R. Storey, and R. Moore 2001. Principles of Botany, 1st ed. McGraw Hill, Dubuque, IA.
- Burnie, David. 2000. Plant. Dorling Kindersley Eyewitness Books, New York.
Websites:
For more information about sprouts see the International Sprout Growers Association
This activity is based on an exercise presented by Ken Blom, Niskayuna School District, Niskayuna, NY and was developed and edited by Amy Russel and Steven Rice, Department of Biological Sciences, Union College, Schenectady, NY.