Water Transport in Plants:
Problem and Experimental Design
You now know that water travels up through roots and stems in vascular tissue
known as xylem. The water then enters the leaf and is used in photosynthesis to
make glucose. In a tree, such as the giant redwood of California, water must
ascend over 300 feet to reach the highest leaves. This ascent requires great
forces. In this investigation, you will use young bean plants to discover details
about the forces involved. The factors involved in water transport are basically
the same in all green plants.
OBJECTIVE:
You will be expected to solve two water transport problems as stated below. You will submit
hypotheses for each problem and design and conduct your own controlled experiments. After
collecting and interpreting the data, you will decide if your hypotheses are supported or contradicted.
MATERIALS:
4-5 red kidney beans that have germinated
5 test tubes (150 mm x 25 mm)
100 ml graduated cylinder
razor blade
Container for soil (for pre-lab)
balance
test tube rack
beaker (600mL - 1L)
sharpee
ruler
tape
PRE-LAB ACTIVITY
1.
2.
Fill a container 1/3 full of soil. Take one bean and place it in the container, root side down. Cover the bean with
soil so that it reaches the bottom of the rim of the container. Water the bean gently, as not to erode any soil above
the bean.
Continue to water every other day for 1-2 weeks until all the plants have developed leaves.
DAY ONE:
The following brief pre-lab experiment will provide valuable information you will need to solve the
lab problems that follow: work as one team at your table for the pre-lab.
1. Clean out your test tubes before using them. Any contaminates may kill your plant.
2. Pour tap water into a test tube to within about 1-2 cm from the top. Use a graduated cylinder to
determine how many mL of water are in the test tube and return the water to the test tube.
3. Pour an equal amount of water into the rest of your test tubes of the same size.
4. Record the number of mL of water placed into each tube.
5. Obtain 4-5 plants that are approximately the same size.
6. Remove the bean plants from their container by gradually shaking them out over the designated
container. CAREFUL – do not rip out any of the root hairs during this process! Gently
remove all the soil from around the stem and roots. This should be done over a container; if
any soil lands on the table or floor, clean it up immediately. If a small amount of soil remains
you may rinse it in a beaker, as long as all the big chunks have been removed first.
7. Place the bare-root bean plants carefully into their own
tubes of water so as not to damage the roots or break
the stem. Gently push the roots down into the tube and
rest the plant so that it doesn’t fall down into the tube.
8. Label your test tube rack with your group and period.
Place this in a warm and lighted place in the room until
the next school day.
9. Complete Day 1 on the worksheet. Predict what will
happen (use specific numbers) to the water level in
each tube.
DAY TWO:
Pre-lab results and designing your experiments:
1. Remove one of the plants carefully and measure the amount of water remaining in
its tube and the plantless tube with a graduated cylinder. Place the plant back in
tube with water when done. Any volume is fine, it’s just to keep it alive until
tomorrow.
2. Create a data chart showing the original number of mL of water placed in each
tube, the number of mL today, and the difference.
3. Complete the rest of the worksheet for Day 2.
DESIGNING THE EXPERIMENTS (Homework):
Your obligations are as follows:
1. Create two hypotheses and design experiments to answer the two questions that
follow. Check the materials section on the previous page to see what is available
to you.
2. Perform the experiments and collect the data. (This will happen on day 3)
3. State valid interpretations and conclusions. Write a report that follows the formal
lab write-up format. (This will happen after day 4)
DESIGN EXPERIMENTS THAT WILL PROVIDE ANSWERS TO THE
FOLLOWING TWO QUESTIONS:
PROBLEM ONE:
What role does the number or size of the
leaves (leaf surface area) play in the movement
of water through a plant?
On your own paper, copy the problem and then state and label your hypothesis. Under
the methods heading, draw diagrams that would illustrate how you would set up
experiments to test your hypothesis. Remember, check the materials section on the
previous page to see what is available to you. Explain the details concerning all parts of
the experiment that aren’t clear on your diagram(s).
PROBLEM TWO:
Which force plays the most important role in
the movement of water through a plant: the
absorption of water by the roots or the
evaporation of water from the leaves?
On your own paper, copy the problem and then state and label your hypothesis. Under
the methods heading, draw diagrams that would illustrate how you would set up
experiments to test your hypothesis. Remember, check the materials section on the
previous page to see what is available to you. Explain the details concerning all parts of
the experiment that aren’t clear on your diagram(s).
DAY THREE: EXPERIMENTAL DESIGN & EXPERIMENTATION
1. After you have designed the experiment for homework, you will agree upon
which procedures to follow as a group and carry out the procedure.
2. Complete your experiment as directed.
3. Be very careful to not break the stems and leaves when placing your plants in the
test tubes.
4. Be sure to labeled your groups tubes and place them in a fully lighted area for 24
to 72 hours.
5. Open a google doc, write all group members names and give it a title. Type the
procedure you just followed and share the document with your group members.
DAY FOUR: OBSERVING RESULTS
1. Gather and record all data as described in your experimental design.
2. Present your results in a clear data chart. You can do a rough draft now but later it
will need to go into your shared google document.
3. Clean all tubes, remove all tape or labels, and place all bean plants into the
compost container provided.
4. Turn the tubes upside down so they can dry.
5. Check with other groups to see if your data was similar.
DISCUSSION (to be completed as a group)
1. Each of the tubes containing plants lost water. How do you know how many mL
of this water loss was due to evaporation?
2. Do the number of leaves (surface area) make a difference in water uptake in bean
plants? Explain.
3. Compare the loss of water from the tube with a whole plant (control) with the loss
of water from a tube with a plant without roots. What is the difference in values?
How many mL of water are the roots alone responsible for moving?
4. Compare the loss of water from the tube with a whole plant (control) with the loss
of water from a tube with a plant without leaves. What is the difference in values?
How many mL of water are the leaves alone responsible for moving?
5. Based upon the calculations for questions 3 and 4 above, are the roots or the
leaves responsible for moving more water?
Write CONCLUSIONS regarding each of your hypotheses based on the
McMush/enzyme lab example. Be sure to separate/number each section.
NOW, GO BACK A WRITE AN INTRODUCTION. Be sure to follow the blue
handout on the lab write-up format so you don’t lose points.
Share the completed document with Mrs. Cardellini: [email protected]
Water Transport in Plants Pre-Lab
Name: ______________________________
Per. _______ Date: _________
Day One:
1. How much water did you put into the test tube? _______
2. Prediction (see #9 on the procedure):
3. Why set up a test tube with water and one with a plant?
4. What are the tubes called that transport water and food in a plant?
Day Two:
1. Data Chart:
2. Explain what accounts for the loss of water in each tube.
3. How much water was actually taken up by the plant each day? (show work)
4. Think about what you have learned about plants – in what areas does water move through a
plant? List them all:
Homework – Experimental Design
Write a problem, hypothesis and experimental design for both problems. Attach a separate sheet of
paper if need be.