Biology 215 Labs: Scientific Method

Bio 215 Home Lab Schedule

In this laboratory you will experiment with the scientific method, identifying a problem, making predictions, performing an experiment and coming to conclusions. This experiment will be designed and carried out as a class, and the results will be combined and conclusions made. Answer the questions below and in the "For furhter thought..." section to better prepare you for the laboratory session.

Problem: The problem comes from making observations and asking questions. In this case, you are looking at heart rates for a variety of animals. What is the question or problem?

Hypothesis: The educated guess is a prediction of what you think the results are going to be. It is not just a "guess", but an educated guess. You must educate yourself on the background of the problem, before you are able to come up with an hypothesis. Read this lab thoroughly and read in your textbook about how heart rate relates to the independent variable discussed in this lab.

Experimentation (Testing your hypothesis): The hypothesis from above must be something testable. In designing your experiment, you must include a control. A control is an alternate test of your hypothesis where only one variable differs from the first trial.

Results: How will you record and display your results? Be sure to measure and record both variables adequately. Both tables and graphs may be used.

Conclusions: Based upon your observations and results of the experiment performed today (and the data given to you in your lab) make conclusions regarding the relation between heart rate and temperature.

 

Tips and Hints:

Daphnia are crustaceans. Their transparent heart is located dorsal to the digestive tract, as shown below. The heart beats very fast and steadily; if you see an appendage with jerky movements, it is not the heart, but perhaps the legs.

Use the mesh netting provided to stabilize the daphnia on your watch glass. Put the animal on its side and press it into the net. Choose a large daphnia! Prepare to work together as a team with one person watching and counting, and another member of the team recording the results.

Graph all of the data provided in Table 3 on one grid. Make sure the parameters of the grid encompass the entire range found among all the animals in the table.
Temperature range is therefore 0°C to 60°C and Heart Rate is 0 Beats Per Minute (BPM) to 500 BPM, unless the daphnia goes higher than that.

Below is one example of a graph. The x-axis (horizontal) displays the Independent Variable, temperature and the y-axis (vertical) displays the Dependent Variable, heart rate.

Once you have plotted all the points on your graph, take a ruler and line it up on the graph so that approximately one-half of the plotted points lie above the ruler line and one-half lie below the plotted line. Draw the line. DO NOT CONNECT THE DOTS. You will learn through experience and reading the results from many other experiments when it is appropriate to connect the dots and when you are looking for trends in the data and draw a line as described above.

When you have finished drawing the line, your graph may look something like this:

 For Further Thought...

1. How would the energy spent by ectothermic organisms compare to that of endothermic organisms?
2. Which of the following animals are ectothermic?
3. Which of the following animals are endothermic?