Grade Level: 9th - 12th; Type: Life Science
Student observes the increasing production of hemoglobin in Daphnia magna as a response to decreasing oxygen concentrations.
- What is the role of hemoglobin in the body?
- How is hemoglobin produced?
- Why might hemoglobin concentrations in the body increase?
- Why might hemoglobin concentrations in the body decrease?
- How do you keep Daphnia alive?
- What is the role of hemoglobin in Daphnia?
- How might decreased dissolved oxygen levels affect hemoglobin production in Daphnia?
- How might decreased atmospheric oxygen levels affect hemoglobin production in humans?
Daphnia magna are small crustaceans that live in freshwater ponds and streams. Also known as ‘water fleas’, Daphnia feed on free living algae and themselves are an important food for fish and other larger animals. They are sensitive to poor water conditions and are sometimes used to determine water quality. Hemoglobin is a protein in the blood that carries oxygen from the lungs or gills to the cells of many organisms. In this experiment, the student will manipulate the oxygen concentrations of the water in which the Daphnia are kept, to evaluate the hemoglobin production of the creatures.
- Daphnia magna Culture Kit available at http://www.carolina.com/product/142304.do
- Magnifying glass and/or microscope
- Digital camera
- Sketch book and colored pencils
- Petroleum jelly
- Plastic wrap
- Obtain a Daphnia magna culture kit and follow instructions to set it up and establish your culture. Observe your Daphnia population. Use a magnifying glass or microscope to help you see small details of their bodies. Take pictures of your initial culture and make a sketch of an individual Daphnia. You can use a bit of petroleum jelly to hold an individual Daphnia for observation. Be sure to color the sketch accurately with colored pencils.
- Create your hypothesis. What do you think will happen to the Daphnia as the oxygen concentration of their environment is decreased and why? Feed your Daphnia to prepare them for the low oxygen experiment.
- Carefully cover the surface of the water in the aquarium with plastic wrap. This will prevent gases from entering or leaving the surface of the water. As the Daphnia use up the oxygen and produce carbon dioxide, dissolved oxygen concentrations in the water will drop. Observe your Daphnia over the next 2-3 weeks. Each day, take a picture of the population. Record any changes. Especially pay attention to the color of the Daphnia. Since they are transparent, the color change you observe should be a direct result of the change in their blood and hemoglobin synthesis.
- After 2-3 weeks, remove the plastic wrap. Take pictures of the population and make another sketch of an individual Daphnia. Color the sketch accurately to show any changes that have taken place. Feed your culture and allow them to return to normal without the plastic wrap. Observe them daily and take pictures. After week or so, if they are back to normal, sketch another individual.
- Conclude your experiment by assessing your hypothesis. Did the Daphnia change in the way you predicted? Display your sketches. Show your daily observation results with a bar or line graph.
Terms/Concepts: Daphnia magna; Freshwater invertebrates; Freshwater ecology; Hemoglobin; Protein synthesis; Dissolved oxygen; Cellular Respiration
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