Prediction: How do you think the temperature affects breath rate?
As the temperature increases, the respiration rate will:
increase, decrease, or stay the same. (circle) Any answer is valid, try to get students to at least think about the question
With younger students, it may be easier to assign half of the class to do the cold water tests and the other half to do the warm water tests and then combine the data. This will reduce the stress on the fish and allow the lab to be completed faster.
|Your Fish||Fish 2||Fish 3||Fish 4||Fish 5||Average|
Generally the fish breathing rate should go down as the temperature goes down. Answers can vary as students may have trouble counting the gill movements. It is important that the water bath is not heated above 30 degrees, hot water is the cause of most fish fatalities in this lab; goldfish are actually very tolerant of cold water.
Also, get enough fish for all of your classes. Fish will recover but it is best if you wait a day or so before doing the experiment on them again.
|18-22 C (room)|
|10 or below|
Students may have trouble setting up the graph. Make sure they make a LINE graph that shows a separate line for their fish and the average.
1. Describe how the fish's respiration rate changes with the temperature. As the temperature is decreased, the breathing rate also decreases
2. Propose an explanation for why the respiration changed in this way. Fish are ectothermic (cold-blooded) and their metabolism is affected by the outside temperature
3. What other factors (besides temperature) may have affected the rate? Stress on the fish, such as moving the beakers, stirring the water
4. Was the “average” similar to your fish data? Why do we take an average? averages give a broader view, can be more accurate than a single fish
5. Was your prediction at the beginning of the lab correct or incorrect? answers vary
6. Design an experiment that will test how a fish's respiration rate is affected by light. Explain your design. You may wish to draw a picture of your set-up. Include how you will change the environment and what you will be measuring.
The design should be logical, should include monitoring fish breathing in the light and in the dark to see if it changes.
7. Supposing this experiment was repeated using an endothermic (warm-blooded) animal as a test subject instead of a fish. Heart and breathing rate is monitored for a mouse as the temperature is raised and then lowered. Will the mouse’s breathing and heart rate change? Why or why not?
mouse will not change, they are endothermic
8. Indicate on the graph which line would represent the endothermic animal and which line would represent the ectothermic animal. Explain how you know this. The top line is the fish, the lower line is the mammal, the mammals respiration change stays about the same