Science JunctionLesson 1

 Does a fluctuation in temperature effect the growth and survival rate of aquatic plants?

Students will be able to: Note: Safety goggles and aprons should be worn at all times during this lab activity.

Fresh water sample from a local pond or aquarium
6 test tubes
6 portions of duckweed or elodea
3 thermometers
3 beakers or test tube racks to hold test tubes
hand lens or dissecting microscope
Petri dishes
Refrigerator (preferable) or ice bath
Incubator or light source

Working with a partner:
1. Using  a hand lens or a dissecting microscope, examine a portion of the plant to be used
in this experiment.
Describe the characteristics of a healthy plant.

2. Label 6 test tubes as follows:

3. Fill each test tube approximately half full with the fresh or aquarium water sample.
4. Add a sprig of the plant to each test tube.
5. Place the test tubes in a rack or a beaker and place each group of two in the appropriate
location. 6. Place a thermometer in each location as close as possible to the test tubes.
7. Take a temperature reading from each location after approximately 10 minutes. This
will allow time for the temperature to stabilize.
8. Record the temperature readings in the data table under Day 1.
9. Based on your knowledge of aquatic ecosystems and temperature, hypothesize how the
cultures will change over a 24 hour period.


10. Record each of the temperature readings and observations on the data table for the next four

Data Table:


After the observations are complete, answer the following questions

1. Based on your observations, what would be the optimal temperature for the growth and
development of aquatic plants?

2. Based on your observations, what would happen to plants in an aquatic ecosystem if the
temperature increased or decreased?

3. How would this effect the aquatic ecosystem as a whole? (Consider other organisms
such as macroinvertebrates and fish)

4. Research the effects of thermal pollution on aquatic plants. Write a short paragraph
explaining what thermal pollution is and how it effects an aquatic ecosystem. In addition,
include how this problem can be alleviated.

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©1998 April J. Cleveland for Science Junction, NC State University. All rights reserved.
page design by Lisa Leonor Grable and April J. Cleveland
URL: http://www.ncsu/scijunct/depot/experiments/water/lessons/temp/templesson1.html
Last Modified: 6/2/98

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