Introduction: (Initial Observation)
All plants are alive and need nutrients and water to survive. But how do nutrients and water move through the plant?
Do plants absorb water through their leaves? stem? root?
Does water move in a specific direction? for example from root to leaves or from leaves to root?
How this movement is achieved? what forces and processes are involved?
Find out about what you want to investigate. Read books, magazines or ask professionals who might know in order to learn about the effect or area of study. Keep track of where you got your information from.
Water enters the root (often well below the soil surface) and much of it ends up at the leaves, which in some tree species can be up to 100 meters above ground level.
Air enters the leaves through small holes in the leaves called stomata. When the stomatas are open they let air in but they also lose water through evaporation. The stem of the plant is simply a plumbing system. Water in the xylem is drawn up through the stem by suction from the leaves because water is evaporating through the stomata into the air.
The gradient of water concentration that exists across the root creates a pushing force called “root pressure”, i.e. a pressure that “pushes” the water across. There is a water concentration gradient across the root which means that water which has entered the root hair cell continues to move inward by osmosis.
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 project is to find out how does water move in plants? what forces are involved and what is the path for water movements from the time that it enters the plant until when it exits the plant.
This project involves a few experiments. Each experiment will answer part of our questions. As a display project you will not need a data table and graph. If you want to do this project as an experimental project and have a data table for that, then you may use this question for your project.
How does addition of sugar to the water affect the movements of water in plants?
This question is studied in the experiment 7.
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.
You will not need to define variables for a display project. If you are doing this as an experimental project and want to do the experiment 7, then this is how you select the variables.
The independent variable also known as manipulated variable is the ratio of sugar in water.
The dependent variable also known as responding variable is the speed in which water travels in plant (carnation stem).
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.
This is a sample hypothesis:
Addition of sugar will slow down the movement of water in plant. My hypothesis is based on my gathered information and the fact that sugar water has a higher viscosity and will have a hard time to move up the capillary tubes in the stem.
This hypothesis is being tested in experiment 7.
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.”
Does water absorb through plant’s root?
We want to see if the plant root absorbs water and pumps water up to other parts of a plant. We get a plant root, cut the leaves and most part of stem and place the root in the water to see if water comes out of the stem.
Get a carrot and cut the stem and leaves about one inch above the carrot. Place the carrot in clean water. See if water will rise and accumulate on the stem.
Does water absorb through plant’s root?
We want to see if the plant root absorbs water and pumps water up if there is no stem and no leaves. We get a plant root, cut the stem and place the root in the water to see if water comes out of the root.
Get a carrot and cut the stem where it joins the carrot. Place the carrot in clean water. See if water will rise and accumulate where you made the cut.
If you want to make sure that any possible rising water will have room to stay, you can make a hole on the top of the carrot where the stem used to be
If some water accumulated in the hole, your experiment is completed and you can write the result. If no water accumulated in one day, add a little sugar to the hole and wait one more day. The reason that we place this sugar is that plant leaves create sugar and starch and send it down in the root. So we want to simulate the action of plant leaves.
For this experiment most part of the carrot must stay in the water. About one inch on the top can be outside.
Instead of making hole for water to accumulate, you can insert a plastic pipe in to the carrot. We used a plastic test tube, cut the bottom of it and then inserted into the carrot. In this case also you can use some sugar.
You can repeat such experiments and use them as a part of your display.
Do leaves suck the water up the stem?
We want to see if the plant leaves can pull the water up. We get a plant, cut the root and insert it in water colored by food coloring. Leaves will stay out of the water. we want to see if water and food coloring will enter the plant from the stem.
Make colored water by adding dark red or dark blue food coloring to the water.
Get a carrot plant and cut the root (root is the carrot itself). Insert the plant in colored water. Make observations every few hours for up to 3 days. Do you see any color change in stem and leaves? If you don’t see any color change, cut the stem and leaves and look at the cross-section of stem and leaves. Do you see color spots? record the results.
Do an identical experiment at the same time with stem alone. In other words cut the root and all the leaves. This will help you to see the effect of leaves in sucking the water up.
The same experiment can be performed with celery. You can test with stem alone or stem with some leaves to see which one pulls up more color-water in a certain period of time such as one hour.
Depending on the plant that you test, a cross section must show the color spots where xylem tubes exist.
Do plant leaves absorb water?
In order to see if plant leaves absorb water, we place some leaves in colored-water while the rest of plant is out. If the color enters the plant, that can indicate that plant leaves absorbed water.
Do plant’s stem absorb water?
In order to see if plant’s stem absorb water, we place part of a stem in colored-water while the rest of plant is out. If the color enters the plant, that can indicate that plant leaves absorbed water. About one hour waiting time is enough for this experiment and all previous experiments, however you may continue observations and recording for up to 3 days.
Coloring white carnations
Introduction: While plants absorb water, they also absorb minerals and other chemicals dissolved in water. Some plant growers and flower shops use this knowledge to produce flowers in unusual colors. Now you can find carnations and roses in many different colors including blue, green and purple. This experiment show how you may convert white carnations to any color of your choice.
- Use food coloring to make a cup of colored water. Test the color by rubbing a drop of that on the surface of a white paper. Adjust the color by adding more color or adding more water.
- Get a fresh healthy white carnation and measure the length of the plant.
- Place the plant in the cup of food coloring and secure it so it can stand vertically. Record the time.
- Observe the plant every few hours and every day for 5 days.
- Record the time when the color first appears on the plant. (This often happens in a few hours if the weather is warm).
- Calculate the time it took for the color to travel the length of the stem and report it.
If you are required to have a data table and provide the results using a graph, you may try this experiment.
Experiment 7: How does addition of sugar to the water affect the movements of water in plants?
Many suggest to place cut flowers in sugar water as oppose to regular water so that the flowers will last longer. Sugar water has a higher density and a higher viscosity than regular water. In this experiment you try to see how does sugar affect the speed in which water travels through plants.
- Get 5 cups or beakers, in each cup add 250 milliliter water and number the cups from 1 to 5. To each cup also add 10 drops of red food coloring.
- Label the cup number 1 as control. Do not add any sugar to this cup.
- Add 10 grams sugar to the cup number 2
- Add 20 grams sugar to the cup number 3
- Add 30 grams sugar to the cup number 4
- Add 40 grams sugar to the cup number 5
- Stir each cup for about one minute to dissolve the sugar
- Get five identical, same size white carnations
- Place the cups next to a wall
- In each cup place one white carnation and record the time immediately
- Make observations and record the time the red color appears on each flower
- Enter the time it took for the color to reach to the flower for each cup. Your data table may look like this:
Speed of water movement in plants with different sugar contents
|Type of water
|Cup 1. No sugar
|Cup 2. 4% sugar
|Cup 3. 8% sugar
|Cup 4. 12% sugar
|Cup 5. 16% sugar
- Start time is the time you place a cut stem of carnation in colored water
- End time is the time you observe the color in the flower
- Travel time is the time it took for the color to travel the stem and reach the flower. This is the difference between the start time and the end time in minutes.
- Stem length is the length of stem of a cut carnation in centimeters
- To calculate the speed, divide the stem length by the travel time. Calculated speed is based on centimeters per minute. You may multiply the speed by 60 and report it as centimeters per hour.
Note: When you add 10 grams of sugar in 250 milliliter of water, that is almost a 4% solution because it is equal to 4 grams sugar in 100 mL of water.
Make a graph:
You may make a bar graph to visually present your results. Make one vertical bar for each of the cups. Name the bars with the amount of sugar in water. For example you may name the bars like 0%, 4%, 8%, 12% and 16%. The height of each bar will show the speed of traveling water (colored water) in plant.
Materials and Equipment:
- carrot plant
- Food coloring
- Clear plastic or glass cups or similar containers.
- Other household items (knife, sugar,…)
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.
- Did water absorb by root?
- Did water absorb by stem?
- Did water absorb by leaves?
- Do roots force the water up when they are not attached to the rest of the plant?
- Do roots pump water up when connected to the stem and leaves?
- Do stems alone assist in moving water?
No calculation is required for this experiment.
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.
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.
This is a sample conclusion:
Water in the plant is drawn up the stem by suction from the leaves because water is evaporating through the holes in the leaves into the air. It is this evaporation, known as transpiration, which is the driving force for pulling water through a plant.
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.
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.
Food dye needs to be dissolved in the water prior to the experiment.
If you are required to have a data table and provide the results using a graph, you may try experiment 7 or you may use what you have learned in this project guide and come up with a new experimental question for your project. Some possible experimental questions are:
- How does temperature affect the movements of water in plants?
- How does addition of salt affect the movements of water in plants?
Click on “How to start” in the control panel and learn how to define your hypothesis, variables, and how to make a graph.
Movements of water in plants can be measured and recorded by observing the water level in a test tube or a cup that holds the plant. Plants that you use for your experiments must be identical.
For example you may place three identical plants in three identical cups of water and place one of them in refrigerator, keep one at room temperature and keep the other one in a warm room (or next to a heater) .