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Science Project  
What Is the Effect of Water Temperature on the Amount of Color in Spirogyra Plants?

Researched by Carissa H.


The purpose of this experiment was to determine the effect of a certain species of algae when they are growing at different temperatures. 

I became interested in this idea when I saw that more algae was on the beach in Oregon then there was on the Washington shore.

The information gained from this experiment can help people who grow and use algae to know how warm or cold the algae should be growing in.


My hypothesis is that the algae will grow better in water at about 20 degrees Celsius. I also think that algae won’t grow when the water is either extremely warm or extremely cold.

I base my hypothesis on the fact that algae grows pretty well in Washington water where the water is not very warm, but grows better in Oregon where the water is a few degree’s warmer.

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The constants in this study were:
* The amount of algae 
* Type of algae
* Size and type of every container
* Length of time growing
* Amount of water in every container

The manipulated variable was he temperature of the water that the alga was growing in.

The responding variable was the growth of the algae after one week. 

To measure the responding variable I used a colorimeter to see how much color there was in the different plant samples. 

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Spirogyra Plants




4 liters


Vacuum flask


Glass fiber filters


Magnetic Stir bar

Magnetic Stirrer


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1. Order algae plants (spirogyra) from a science magazine. 
2. Gain access to a colorimeter.
3. Gather all materials.
4. Sort out containers.
5. Fill a container with half a liter of 35 degree Celsius water.
6. Place in an area which receives light most of the day.
7. Add 1 milliliter of algae plants.
8. Repeat steps 5-7, 4 times each time decreasing water temperature by 5 degree’s Celsius.
9. Let groups grow for 8 days.
10. Try to grow all plants at the same air temperature.
11. Arrange to use a colorimeter.
12. Place a magnetic stir bar into every container.
13. Using the magnetic stirrer, stir every container for 30 seconds.
14. Measure out 30 milliliters of water and plants.
15. Next using a vacuum flask filter the plants from the water using a glass fiber filter.
16. To assemble the vacuum flask place a blank filter at the top of the flask and fasten a funnel to the top of the container.
17. Filter the five groups.
18. Next using a colorimeter measure the amount of color on a clean glass fiber filter.
19. Then Measure the amount of color on the 5 samples, so that the center of the filter is in the center of the glass part of the colorimeter where the   color is measured.
20. Then measure how much color there is on the different filters with the colorimeter.

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The original purpose of this experiment was to measure the amount of color in five different groups of algae plants each growing at a different temperature.

The results were that the plants growing in water at about 35 degree’s had the most color in them.  The plants that were growing in water at about 25 degree’s had the least color in them. 

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My hypothesis was that the plants growing at 20 degree’s would have a higher amount of color.

The results indicated that this hypothesis should be rejected because the plants grew best at 35 degree’s Celsius.

Because of the results of the experiment, I wonder if all algae plants grow best in water around 35 degree’s.

These findings could be useful to the people because farmers who grow algae will know what temperature the water should be for the plants.  Also people who want to prevent algae growth could use water at about 25 degree’s. 

If I were to conduct this experiment again I would use distilled water instead of tap. I would also try harder to keep the water temperature the same. 

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Plants help us in a variety of ways.  One of the most important ways is by producing oxygen. Some plants also serve as food for people and animals.  There are many species of plants. Some are very large while others are quite small. Just because you can’t see a plant with your eye doesn’t mean it’s not there. Somehow even tiny plants can help us in big ways.   Light is very important for warmth and oxygen.  Colorimeters measure the amount of color in an object.


Plants can come in many different shapes and sizes.  They grow all over the world.  You can find a plant in almost any place at anytime.  Plants that grow in just water are helpful too. Algae are a major group of water plants.  Plants provide oxygen through a process called photosynthesis.  Photosynthesis is when plants use chemicals to change chemical compounds into oxygen.    Chlorophyll absorbs water and carbon dioxide.  Sunlight provides energy for photosynthesis to be able to happen.  In the process chemicals change carbon and water become carbohydrates.  There is always twice as much hydrogen as there is oxygen.   The amount of light needed in the process is called photoperiodism.  Different amounts of light are needed when plants are producing oxygen.  Plants can grow almost anywhere.


There are four main groups of algae.  A major group is blue green algae. These algae have no nuclei and they have a gross taste and odor. Blue green algae are also a slimy growth in shallow areas. Brown algae can be large and small.  One of the largest is
Over 200 feet while the smallest ones are microscopic.  Brown algae live in salt water and are mainly considered seaweed. Another algae group is red algae.  Red algae are smaller than brown algae. This species grow in the ocean.  They are coral and coral reefs mostly. 
The fourth group is green algae. Green algae are cells with definite nuclei. Chloroplasts are a part of the green algae species.  They live in fresh water where it is cool, moist and light. A plant called spirogyra is  a green algae species.  Spirogyra is a spiraled chloroplast.  Algae can be found almost anywhere. 


Colorimeters are used to measure the light in an object.  Absorption and emission happens when there are molecules that light has made.  A Colorimeter measures the intensity of an object.  Colorimeters measure how much color there is in an object.


Light is very important to everyone and everything everywhere. Without light there would be far less natural heat and there would be no difference in seasons.  Light also helps green plants to make oxygen.  Without light there would be no heat or air.  Light bounces off an object into our eyes.  Light is made up of atoms that absorb energy.  They absorb energy from the sun.  They can also absorb energy by bouncing off of other particles.  When they absorb energy by colliding with other particles, they are called an excited atom. The stage when they are an excited atom is very brief. During this stage they do not emit, or give off light.  Atoms can also be excited by heating them.  Reflection occurs when light is reflected by a smooth surface.  Light is very important to everyone.


Plants are important because they give off oxygen.  There are many species of plants, one of which is algae.  Colorimeters measure the amount of color in an object.   Light is needed everywhere all the time. Top of Page


C.J.H., "Photoperiodism," World Book Encyclopedia, 1947, p. 6308.

Fasset, Norman C, A  Manual of Aquatic Plants, Madison 6, Wisconsin, McGraw-Hill, 1940

Fenton, Sharon, "Schools Online,"

G.I.BU., "Photosynthesis," World Book Encyclopedia, 1947, p. 6308

Lenny, "Hanna Instruments Ltd.,"

L.H.T., "Algae" World Book Encyclopedia, 1947, p. 215.

Rhodes, Russell G., "Algae," World Book Encyclopedia, 1999, p. 349.

"Spirogyra," World Book Encyclopedia, 1947, p. 7654.

Walker,Jearl, "Light," World Book Encyclopedia, 1995, p. 282-292.

"Waterwatch Victoria-Manual,"

Whallon, Joanne, "Microbe Zoo,"

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