Principles of Biology By Frank H. Osborne, Ph. D. Lab 1 - Scientific Method

The Scientific Method A. Something is observed to occur. B. An explanation is proposed. This is called a hypothesis. C. An experiment is made to test the hypothesis. D. The results of the experiment are analyzed. E. The hypothesis is either supported or disproved.

Demonstration of Scientific Method A. The relationship of the breathing rate of a goldfish to the temperature of the water in which the fish is located can be tested. B. In an experiment, everything is supposed to be constant with the exception of one variable. C. One fish is experimental. Its temperature is changed from 9° to 27°C. D. Another fish is the control. Its temperature is held constant at 15°C.

Demonstration of Scientific Method E. Nothing else is allowed to change. For this reason, after the temperature of the water is adjusted, any water above the top of the tape on the jar is removed.

How a Goldfish Breathes A.The gills 1.The goldfish uses gills to breathe. 2.It has to pump water over the gills constantly to breathe. 3.The gills are inside of the body of the fish so they cannot be seen.

How a Goldfish Breathes 1.The fish takes in water through its mouth. 2.The fish closes its mouth 3.The fish forces the water over the gills. 4.The water exits the body of the fish under the operculum which covers the gills.

How a Goldfish Breathes

Relationship of Breathing to Water Temperature 1. Fish are called "cold blooded" because the speed of their body functions depends on the temperature. 2. A cold fish functions slower than a warm fish. 3. Therefore, the breathing rate will be slow in cold water and will increase as the temperature of the water is increased.

How to Report Results Graphs 1. The graph is a picture of the data. 2. A graph has two axes. a. The x-axis is horizontal b. The y-axis is vertical.

How to Report Results Graphs We only use the upper right quadrant so our graph will look like an L-shape.

How to Report Results Data 1. Data are always found in a data table. 2. The data that you count are the dependent variables of the data table. They are plotted on the y-axis.

How to Report Results Data 3. The data that are measured (like time or temperature) are the independent variable. It is usually printed across the top of the data table. They are plotted on the x-axis.

Plotting the Graph 1. Mark the x-axis with an appropriate scale for temperatures. 2. Label the x-axis with TEMPERATURE and put the units used to measure the temperature in parentheses (°C).

Plotting the Graph 3. Mark the y-axis with an appropriate scale for counts per minute. 4. Label the y-axis with AVERAGE RATE OF MOTION and the units used to measure it (cpm).

Plotting the Graph 5. At the top of the graph write a title, such as RELATIONSHIP OF BREATHING RATE OF GOLDFISH TO TEMPERATURE.

How to Report Results Plotting the Graph 6. In the lower right corner of the graph make a KEY that tells which line belongs to which group of averages.

How to Report Results Plotting the Graph a. Use different colored pencils to represent the lines on the graph and in the KEY.

How to Report Results Plotting the Graph b. Or, use one color pencil and different types of lines for the graph and the KEY.

How to Report Results Plotting the Graph c. Or, or use symbols that are connected with lines for the graph and the KEY.

The graph as it appears so far.

Plotting the Graph 1. Using a calculator, compute the average of the counts per minute. 2. Plot points on the graph for the oral movements of the experimental fish. 3. Using a ruler, connect the points. 4. Repeat this for the opercular movements of the experimental fish.

Appearance after Experimental Results

Plotting the Graph 5. For the control fish, remember that the first measurement was made when the experimental fish was at 9°C and the final measurement was made when the water temperature of the experimental fish was 27°C.

Plotting the Graph Therefore, plot the following trial 1 on the 9°C line trial 2 on the 12°C line trial 3 on the 15°C line trial 4 on the 18°C line trial 5 on the 21°C line trial 6 on the 24°C line trial 7 on the 27°C line

Final appearance of the graph

Plotting the Graph Additional Notes In science, we use numerals and symbols to represent quantities and measurements. Thus, we write 9°C and do not spell out the amounts nor the units of measure. Therefore, do not write "nine degrees Celsius" out in words.

Plotting the Graph Additional Notes When numbers less than 10 are used, you spell them out when they are quantity but use the numerals if they are measurements. We would write, "We used four fish which were kept at 9°C." Always write out any number that is used to begin a sentence.

How to Report Results Additional Notes Learn the difference between its and it's. its - possessive pronoun (The goldfish takes water in through its mouth.) it's - contraction of it is. (It's about time you learned the difference.) If the words "it is" do not make sense in the sentence when you use "it's" then you are using "it's" wrong.

The End Lab 1 Scientific Method